CTEC 493: Formatted: Font: Times New Roman, Font color: Red OCCUPATIONAL SAFETY AND HYGIENE IN CHEMICAL AND ALLIED INDUSTRIES Formatted: Font: Times New Roman COURSE OUTLINE Formatted: Font: Times New Roman, 12 pt 1. Industrial Hazards Recognition and identification Hazard, risk and exposure Clearance mechanisms Adverse health effects 2. Monitoring Hazardous Substances Sampling and evaluation Quality control Health surveillance Legislation 3. Risk Assessment Information sources Task analysis 1 Page 1 of 60 Recording and reviewing 4. Workplace Control Ventilation Respirators Noise COURSE ASSESSMENT (3 credit hours) 1. Assignments (10 %) Formatted: Tab stops: Not at 1" 2 assignments on section 1 and 2; 1 assignment each on section 3 and 4 2. Tests (10 %) Formatted: Tab stops: Not at 1" 1 test on section 1 and 2; 1 test on section 3 and 4 3. Project (20 %) Formatted: Tab stops: Not at 1" Industrial assessments 4. Final examination (60 %) 2 Page 2 of 60 Formatted: Font: Times New Roman CTEC 493: OCCUPATIONAL SAFETY AND HYGIENE IN CHEMICAL AND ALLIED INDUSTRIES COURSE NOTES Synopsis: This is an introductory course in Occupational Safety & Hygiene (OSH) dealing mainly with chemical hazards in the workplace. Lecture1: 1. INTRODUCTION Formatted: Font: Times New Roman Definition of OSH; and Significance Key Questions: (1) What is Occupational Hygiene? (2) What is Occupational safety? (3) How does Occupational Hygiene differ from Environmental Hygiene? (4) How does OSH contribute to occupational health as well as productivity and profit? OSH is the cross-disciplinary area concerned with the protection of the safety, health and welfare of people engaged in work or environment. Occupational Hygiene is the discipline of anticipating, recognizing, evaluating and controlling health hazards in the working environment with the objective of protecting worker health and well-being and safeguarding the community at large. The term is generally synonymous with Industrial Hygiene 3 Page 3 of 60 Environmental Hygiene addresses similar topics to Occupational Hygiene, but is not confined to the work-place concerned. In common usage Occupational hygiene has taken on a much narrower definition linking it to cleanliness, frequently leading to the misunderstanding of the term Occupational hygiene, which is NOT about hand washing or handling food properly at work. The Occupational Hygienist may be involved with the assessment and control of physical, chemical, environmental and or psychosocial hazards in the workplace that could cause disease or discomfort. Physical hazards may include noise, temperature extremes, illumination extremes, ionizing or non-ionizing radiation, and ergonomics. Indoor air quality (IAQ) and safety may also receive the attention of the Occupational Hygienist. As part of this activity, the Occupational Hygienist may be called upon to: o communicate effectively regarding hazard, risk, and appropriate protective procedures; o to evaluate and occasionally to design ventilation systems; and o to manage people and programs for the preservation of health and well-being of those who enter the workplace. In brief, Occupational Hygienists are responsible for recognizing, evaluating and controlling environmental hazards resulting from physical, chemical or biological factors in the workplace. By assessing and resolving practical problems in a wide range of settings, occupational hygienists help protect workforce health and wellbeing at all levels, and in all areas. Occupational hygienists play a vital role in assessing potential risks to workforce safety in environments including factories, offices and building sites. 4 Page 4 of 60 They enable organizations to respond effectively to the requirements of legislation on issues such as asbestos, noise and manual handling. Occupational hygienists often work within a team with other professionals, such as doctors, nurses and engineers. Typical work activities Work activities will vary according to specialist area and employer but may include: undertaking workplace surveys; assessing the risks to health arising from many different factors, for example chemicals, noise, poor lighting or ventilation; Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman accurately measuring and sampling levels of exposure; using specialist equipment in a precise way; accurately recalling facts or details of procedures in the workplace; evaluating situations in the workplace; analyzing and resolving specific problems; recommending remedies or control methods; compiling data and writing reports; presenting report findings to clients; liaising with a wide range of people in the process of evaluating workplaces, which may include company management and staff; considering all options of control (ventilation, containment, personal protective equipment etc); Formatted: Font: Times New Roman, Not deciding upon or devising the most appropriate method for specific situations; Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman providing clear and accurate information on complex health and safety issues; training organization staff on health and safety issues, such as asbestos and COSHH (Control of Substances Hazardous to Health) awareness; Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman 5 Page 5 of 60 gaining the confidence and co-operation of the workforce; persuading company management to develop effective hazard controls when required; writing guidance information on health and safety; working as part of a team to meet the same objective; keeping up to date with scientific and legal developments; providing expert witness services; Liaising with outside bodies, such as The Health and Safety Executive (HSE) and the Royal Society for the Prevention of Accidents (RoSPA). Every business needs these six professional pillars of an occupational health program. Do you have them in your business? 1. Occupational Hygienist: trained to recognize, evaluate, control and workplace exposures. prevent 2. Safety Professional: engaged in the prevention of accidents, incidents, and events that harm people, property, or the environment 3. Occupational Health Nurse (OHN): specialist that provides and delivers health care services to workers and worker populations 4. Occupational Physician: a licensed medical doctor with special training and experience in the health hazards of workers 5. Emergency Preparedness Professional: responsible for defining and each employee's role during an emergency communicating 6. Environmentalist: responsible for the management of several programs related to environmental protection, most commonly: Hazardous Waste Management and Disposal, Air Quality, Water Quality and Recycling/Reclamation. Usually these professionals will report to the Safety, Health and Environment (SH&E) Manager of the respective company where they work. The SH&E manager will have a program called 6 Page 6 of 60 Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... SH&E program driven by an SH&E policy. This policy integrates all the above functions into one program, the SH&E program. Do you have such a program at your workplace? This is one of the determinants of sustainability of your business. Formatted: Font: Times New Roman End of Lecture1: 12/08/2009……………………………………………………………… Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Lecture 2: Introduction (Cont……) Why Managing Health & Safety? There are lots of reasons why corporations need to manage Health & Safety; but these may be into 3 broader groups given below Formatted: Font: Times New Roman, Not . Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman Moral & ethical issues/reasons: o Respect human resources /workforce Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman o Respect their families Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Legal Issues: o Compensation claims o Disruptions during legal processes Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Financial Issues: o Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Increase of insurance premiums – bad reputation attracts higher premiums 7 Page 7 of 60 o Direct losses – results of costly incidents with direct financial implications o Indirect losses – costs of an indirect nature e.g. reduced productivity of individual workers due to work-related illness. Formatted: Font: Times New Roman, Not Costs of hazard or risk reduction/elimination. Moral regard for human life and well-being. Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not It is important to note that, the struggle to eliminate or reduce occupation hazards & risks, which often result in illness, injuries and damages that result is chiefly complicated by two mutually opposing aspects: Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Font color: Red Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Font color: Red Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Good news: Many of the large corporations have found the mutual consideration and compromise beneficial and workers are safer to a higher degree than before. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman In return: fewer walkouts, strikes, and inefficient operations because workers were slowed by their need to prevent and protect themselves against hazards; Less costly litigation and lower insurance premium costs. Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Bad News: Many small companies still believe erroneously that safety programs are nonproductive and unprofitable. Consequently, their safety efforts are minimal and accident and injury rates are higher than those of large companies. Formatted: Font: Times New Roman, Not The chief complaint when any new law or mandatory standard concerning safety is being considered or has been enacted is that the increased costs will put them out of business. To such organizations, it therefore appears that monetary aspects are more important than the moral considerations. Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman 8 Page 8 of 60 Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not NB. Different states take different approaches to legislation, regulation, and enforcement. Some have enforcing authorities to ensure that the basic legal requirements relating to occupational safety and health are met. In most developed countries, there is strong cooperation between employer and worker organizations (e.g. Unions) to ensure good OSH performance as it is recognized this has benefits for both the worker (through maintenance of health) and the enterprise (through improved productivity and quality). Formatted: Font: Times New Roman EMPLOYER - EMPLOYEE OBLIGATIONS. What should my employer do to protect my health? • Follow relevant Regulations, • Use safer alternatives • Exposure assessment Formatted: Font: Times New Roman • Steps to prevent exposure or reduce exposure to lowest possible level Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman • Information, training, education • Protective clothing • Demarcation and labeling • Adequate washing and changing facilities, separate storage facilities for personal protective equipment (PPE) and personal clothing Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman • Monitoring: air and health checks • Issue correct mask / respirator • Do everything reasonably possible to protect you Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not • Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not What should I do to protect my health? • Formatted: Font: Times New Roman Make full use of control measures provided by employer Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman 9 Page 9 of 60 • Report faults in air extraction systems • Use protective clothing and masks / respirators when required • Make sure mask / respirator fits properly Formatted: Font: Times New Roman • Do not go into respirator zone without wearing correct mask / respirator Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman • Follow recommended working procedures to reduce dust levels, keep material damp • Work in well ventilated areas or open air • Keep work areas clean by using vacuum cleaning or wet methods • Never use compressed air for cleaning • Never use dry sweeping methods • Cooperate if asked to wear devices to measure your exposure while you work • Do not smoke or cut down as much as possible • Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Wash your hands and face thoroughly before eating, drinking or smoking Formatted: Font: Times New Roman, Not • Do not eat, drink or smoke in the working area • Do not take home clothing contaminated –e.g. with asbestos Formatted: Font: Times New Roman • Wash and change before you go home Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman 10 Page 10 of 60 2. RECOGNITION & IDENTIFICATION OF HAZARDS Sub-topics: Types of industrial hazards. Hazard, risk and exposure. Sources of exposure. Routes of entry into the body. Clearance mechanisms. Adverse health effects of chemical exposure to elemental, inorganic & organic dust, fumes, gases & vapors. Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Lect. 3: Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman 2.1. Hazard, Risk; and Types of Hazard Formatted: Font: Times New Roman, Font color: Black Formatted: Left Formatted: Font: Times New Roman, 12 pt, Font color: Black Hazard –a chemical or physical condition that has the potential to cause damage to people, property or the environment Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Risk – chance or probability of danger, loss or injury occurring. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black A measure of economic loss or human injury in terms of both the accident likelihood and magnitude (consequence) of loss or injury Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black A combination of incident, probability and consequences. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Formatted: Font: Times New Roman, Font color: Black Types of hazards Formatted: Font: Times New Roman 11 Page 11 of 60 Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Can be classified in three groups which are physical, chemical & biological: Formatted: Font: Times New Roman, Not Chemical hazards – these come in different forms/types - gas, liquid, vapor, fumes, mist, or dust. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman o Well known typical chemical hazards are Asbestos, Lead, Hg, etc Physical, e.g., lighting, noise, vibration, slippery floors, sharp protrusions, improperly tacked attire or long plated hair (sometimes) etc. Biological, e.g. fungi, bacteria, viruses Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Font color: Black Formatted: Left Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Relationship between Hazard and Risk Formatted: Font: Times New Roman In OSH Management System, the risk assessment process invariably includes: Identifying the hazard Assessing the risk Controlling the risk Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black o Eliminating the hazard, if possible Formatted: Font: Times New Roman o Minimizing, if possible Formatted o Controlling the hazard ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Checking and Reviewing the risk control Formatted ... Formatted: Font: Times New Roman Formatted How to Assess the Risk? ... Formatted: Font: Times New Roman Formatted Two approaches are used, which are: ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Formatted Subjective (Qualitative) ... Formatted: Font: Times New Roman -Perception Formatted Formatted: Font: Times New Roman 12 Page 12 of 60 ... ‘ ‘-Likelihood and Consequences Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black –Likelihood: Very Often, Often, and Seldom Formatted: Font: Times New Roman –Consequence: Fatal, Major and Minor Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Objective (Quantitative) Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black o Historical data Formatted: Font: Times New Roman o Probability of occurrence (Frequency): Incidents/200,000 MH/Year Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black o Consequence: Measured in terms of Direct and Indirect Cost Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Qualitative Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Font color: Black Formatted: Font: Times New Roman Formatted: Font: Times New Roman 13 Page 13 of 60 Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Left Formatted: Font: Times New Roman, 12 pt, Font color: Black Quantitative Formatted: Font: Times New Roman Example: Historical data for a particular industrial site shows an average-fall-Accident (AFA) of 10 incidents /200,000 MH/year. On average one fall accident costs (FAC) USD 1000. Given: MH = man-hrs; a person works for 50 weeks a yr, 5 days a week and 8hrs/day. Formatted: Font: Times New Roman, 12 pt, Font color: Black Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Font color: Black Determine the estimate fall accident related costs if the site has 200 workers. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Font color: Black Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Solution: Estimate of fall related cost = total MH x AFA x FAC. Formatted: Font: Times New Roman 14 Page 14 of 60 Field Code Changed ( 8hr 5dy 50wk 200man 10accident US1000 )( )( ) US 2000 / yr dy wk yr 1 200000man.hr 1accident Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Font color: Black Alternatively: Formatted: Font: Times New Roman 200,000 = number of hours that 100 employees work in a year (i.e. 40 hrs per week x 50 weeks x 100) Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black So, 100 workers result in 10 accidents, thus 200 workers results in 20 accidents per yr Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Estimated Cost = 20 x 1000 = USD 20,000 / year Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Formatted: Font: Times New Roman, 12 pt, Font color: Black Formatted: Font: Times New Roman Fig 1.1 Position of the workplace hazards and workplace accidents in the procedure of risk assessment Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Fig 1.2 Risk assessment and risk management in the procedure of the quantitative risk assessment Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Fig 1.3 The overlap of the legislation in the field of OSH with the procedure of the quantitative risk assessment Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Left 15 Page 15 of 60 HAZARD – RISK REALATIONSHIP Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman 16 Page 16 of 60 Formatted: Font: Times New Roman Formatted: Left Formatted: Font: Times New Roman, 12 pt, Font color: Black Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Formatted: Font: Times New Roman Risk Assessment Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Prioritize: categorizing the hazards into different groups Formatted: Font: Times New Roman We cannot control all hazards due to limited resources Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Select certain groups for risk elimination, reduction and control Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Font color: Black Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Risk Elimination Formatted: Font: Times New Roman This is the best solution, however sometimes it is not practicable Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Example: Lead-based paint can cause lung cancer Formatted: Font: Times New Roman Solution: replace the type of the paint with water-based paint Formatted: Font: Times New Roman, 12 pt, Not Bold, Font color: Black Formatted: Font: Times New Roman Formatted: Font: Times New Roman, 12 pt, Font color: Black Risk Minimization Formatted: Font: Times New Roman 17 Page 17 of 60 Reduce the number of people exposed to the hazard Change with other types although new ‘safer’ hazards may occur Reduce the exposure of the hazards Risk Control Control the energy/intensity: Fall wear body harness and land-yard Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... ... Noise wear earmuff Formatted Formatted ... Welding wear mask Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Vibrator wear leather glove Chemical wear safety clothe Review and Check Check the effectiveness of the safety risk management Review new hazards and technology Risk Management Steps: 1. Look for hazards 2. Decide who might be harmed & how 3. Evaluate the risk & decide whether existing precautions are adequate or whether more should be done. 4. Record your findings 5. Review your assessment & revise it if necessary. End of lecture 3…………………………………………………………………………. 18 Page 18 of 60 Lect 4: 2.2. OSH from risk analysis and management position Modern occupational safety and hygiene legislation usually demands that a risk assessment be carried out prior to making an intervention. This assessment should: Formatted: Font: Times New Roman, Not Identify the hazards at workplace Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Identify all workers that can be affected by the hazard and how they can be affected Evaluate the risk. Identify and prioritize the required actions. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman The calculation of risk is based on the likelihood or probability of the harm being realized and the severity of the consequences. This can be expressed mathematically as: Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman a quantitative assessment (by assigning low, medium and high likelihood and severity with integers and multiplying them to give a risk factor), or Formatted: Font: Times New Roman, Not as a description of the circumstances by which the harm could arise i.e. qualitative. Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman The assessment should be recorded and reviewed periodically and whenever there is a significant change to work practices. Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman The assessment should include practical recommendations to control the risk. Once recommended controls are implemented, the risk should be re-calculated to determine of it has been lowered to an acceptable level. Formatted: Font: Times New Roman, Not Bold Generally speaking, newly introduced controls should lower risk by one level, i.e., from high to medium or from medium to low. The precautionary principle of OSH is an increasingly used method for reducing potential chemical or biological OSH risks. Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman 19 Page 19 of 60 Formatted: Font: Times New Roman Formatted: Font: Times New Roman Fig 1.4 The overlap of the legislation in the field of OSH with the procedure of the quantitative risk assessment Formatted: Font: Times New Roman, Not Formatted: Font: (Default) Times New Roman End of lecture 4………………………………………………………………………….. 2.3 Toxicology Toxicology is the study of harmful effects to living organisms from substances which are foreign to them. The toxins may be naturally occurring in the environment or synthetic chemicals. The following definitions will describe some basic concepts in toxicology. Formatted: Font: Times New Roman, Not Bold Toxicity can be generally broken down into two categories: Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman Formatted: Font: Times New Roman Acute toxicity: refers to the rapid development of symptoms/effects after the intake of relatively high doses of the toxicant. Acute toxicity refers to immediate harmful effects generated by sufficiently large doses. Formatted: Font: Times New Roman, Not Bold Chronic toxicity: refers to the harmful effects of long-term exposure to relatively low doses of toxicant. This would include traces of pesticides in foods, air pollution, etc. Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman A single compound may generate both acute and chronic toxic effects depending on the dose and duration of exposure. Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Formatted: Font: Times New Roman There are two general types of toxic effect: Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman Lethal Effects: resulting in the death of individuals 20 Page 20 of 60 Formatted: Font: Times New Roman, Not Sub- lethal Effects: other effects not directly resulting in death Formatted: Font: Times New Roman There are four basic types of damage caused by toxic materials: Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman 1. Physiological damage: reversible/irreversible damage to the health of the organism Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman 2. Carcinogenesis: induction of cancer Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman 3. Mutagenesis: induction of genetic damage / mutation(s) Formatted: Font: Times New Roman, Not Formatted: Font: Times New Roman 4. Teratogenesis: induction of birth defects Formatted: Font: Times New Roman, Not Bold Formatted: Font: Times New Roman ERGONOMICS. "Ergonomics is about ’fit’: the fit between people, the things they do, the objects they use and the environments they work, travel and play in. If good fit is achieved, the stresses on people are reduced. They are more comfortable, they can do things more quickly and easily, and they make fewer mistakes." Formatted: Font: (Default) Times New Roman, Not Bold Ergonomics Society (Europe) Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: (Default) Times New Roman Formatted: Left "Ergonomics (or human factors) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance." "Ergonomists contribute to the design and evaluation of tasks, jobs, products, environments and systems in order to make them compatible with the needs, abilities and limitations of people." Formatted: Font: (Default) Times New Roman, No underline Formatted: Font: (Default) Times New Roman Formatted: Font: (Default) Times New Roman, No underline Formatted: Font: Times New Roman Epidemiology In contrast to the rapid effects observed in toxicology, epidemiology examines the relationship between exposure to a specific toxic agent and the development of health problems in a group of humans. In essence epidemiology examines the health patterns in humans with respect to an agent/toxicant. An example might include the health effects of chronic, lowlevel exposure to pesticides found on un-washed fruit. Formatted: Font: Times New Roman, No underline Simply put, epidemiology looks for trends and effects in human health following exposure to a specific compound or other toxic agents. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman 21 Page 21 of 60 iii. Effect of Dose Formatted: Font: Times New Roman, No underline Relative toxicity of a substance is often expressed in the dose-response relationship. This simply relates the dose (quantity administered) of a substance to the response generated in a test organism. In order to relate this information to humans, dose is often expressed as dose per organism weight, or mg / kg (where mg represents toxicant dose and kg expresses animal weight.). It is also important to consider the method of application, whether oral, dermal, intravenous, etc., as these may greatly affect relative toxicity of a given compound. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Very commonly the quantity of a toxicant required to cause death is used as an indication of relative toxicity. This is most often expressed as: LD50 . This expresses the mg/kg dose required to kill 50% of a test population. For example the LD50 for sugar is >10,000 mg/kg, while for the botulism toxin is ~ 0.0001 mg/kg. Obviously the botulinum toxin is highly toxic even in relatively low doses. An alternative measurement of dose response is the ED50 where there is an effect on 50% of the test population. This represents a measurement of sub-lethal effects. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Some Example LD50Values Formatted: Font: Times New Roman Substance LD50 (mg/kg) Formatted: Font: Times New Roman, No underline Sugar >10,000 Formatted: Font: Times New Roman Caffeine 100 Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman 22 Page 22 of 60 Strychnine sulfate 2 Nicotine 1 Rattlesnake venom 0.1 Botulism toxin 0.0001 Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Dose-response curves are generated for various agents by plotting "percent of population affected vs. Dose (mg/kg). When examining such graphs, often there is a minimum concentration (or "threshold") of dose below which there is no observable effect in the test population. This is referred to as the NOEL (no observable effects limit). With respect to human safety, NOEL dose information is often obtained from animal experimentation and then divided by a "safety factor" (i.e. 100) in order to establish safe levels for humans. This generates two kinds of values: ADI (acceptable daily intake) and MDD (maximum daily dose). While these values suggest a large margin of safety, in reality it is quite possible that the more sensitive individuals in a population may still suffer ill effects within the dose limits set by these guidelines. Pharmaceutical safety / effectiveness can be indicated by the pharmaceutical TI (therapeutic index). The therapeutic index is the ratio of LD50 / ED50. A high TI value indicates an effective treatment at low doses and a lethal effect at higher doses. A low TI value indicates an ineffective treatment at low doses with lethality at the same low levels. The objective of using the therapeutic index is to have a pharmaceutical that is highly effective at low doses with Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted Formatted ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman 2.4. Exposure Types & Routes: Formatted ... Formatted: Font: Times New Roman Exposure Typess: Formatted ... Formatted: Font: Times New Roman Typically exposures can be classified according to the duration of the exposure. Formatted ... Formatted: Font: Times New Roman There are four main categories of exposure: Formatted Acute Exposure: describes exposures over a short period of the life of an individual (which may be relatively intense) & the reaction happen in short period of time. An acute exposure is often referred to as being less than 24 hours duration. Sub-acute Exposure: describes exposures over a relatively short period of time, often less than one month. ... Formatted: Font: Times New Roman Formatted ... Formatted ... Formatted ... Formatted: Font: Times New Roman Formatted Formatted: Font: Times New Roman 23 Page 23 of 60 ... Formatted: Font: Times New Roman ... Formatted: Font: Times New Roman, No underline Chronic Exposure: describes repeated small exposures for a long period of time or for "significant" portion of an individual’s life-span. (More than three months for mammals). Sub-chronic Exposure: describes exposures shorter than chronic exposures but longer than subacute (1-3 months is typical for mammals). Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman, No underline Exposure Routes: Formatted: Font: Times New Roman In order for a toxic agent to have an effect an individual (or population) must be exposed. There are several exposure routes: oral (mouth), dermal (through the skin), inhalation (breathing) and /or injection (subcutaneous, intravenous, intramuscular, and intraperitoneal). The specific route of exposure may have a significant impact on relative toxicity: specific substances may even have substantially reduced or enhanced toxicity dependent upon the type of exposure. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Routes of Entry of Toxic Agents Formatted: Font: Times New Roman 24 Page 24 of 60 •Respiratory Formatted: Font: Times New Roman, No underline, Font color: Auto •Skin and eye contact Formatted: Font: Times New Roman Formatted: Font: Times New Roman •Mouth (Ingestion) Formatted: Font: Times New Roman, No underline, Font color: Auto •Injection Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Not Formatted: None, Space Before: 0 pt Formatted: Font: Times New Roman 25 Page 25 of 60 Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... –Headache, Drowsiness, Unconsciousness Formatted ... Formatted ... –Many solvents (toluene, xylene, ether, and acetone) produce this effect if the vapor concentration is high Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... It is rare for chemical interactions with living systems to occur in complete isolation. Often there are specific interactions between multiple agents / chemicals which can be quite different than the action of an individual toxicant. Generally, these interactions can be described as being: 1. additive: compounds X + Y combine toxicity proportionally (i.e. 2+3 = 5) 2. antagonistic: compounds X +Y combine to less toxic than either individually (i.e. 2+3 = 1) 3. synergistic: compounds X + Y combine to be more toxic than either individually (i.e. 2+3 = 9) With these distinctly different interactive effects being possible, it is often very difficult to anticipate combined effects purely on the basis of chemical structure or other isolated data. It is obviously much easier to acquire toxicity-effect data for individual compounds as opposed to complicated mixtures with many unknown interactions. Data on individual toxicity's and safety can be obtained from a number of sources, chiefly: MSDS (Material Safety Data Sheets) - listings that describe (in detail) the known potential hazards for many individual compounds. This type of information usually accompanies commercial chemicals and is also offered on numerous websites. MSDS information includes handling, equipment, safety measures and potential risks / hazards associated with a given substance and can be an excellent starting point for assembling information on a specific compound. Common Typical Toxic/Adverse Effect of Exposure To Chemical Hazards •Irritations –Lung: by inhaling some chemicals, e.g. ozone, sulfur dioxide and nitrogen dioxide –Skin: chemical, physical, mechanical and biological •Central Nervous System (CNS) Depression –Organ affected: brain •Asphyxia - a condition of severely deficient supply of oxygen to the body . –Interfere with the transfer of oxygen –Suffocated because the bloodstream cannot supply enough oxygen 26 Page 26 of 60 –When the oxygen level of 21% drop to 16% Formatted ... –Sources: Gas from sewerage; Argon, propane, methane, Carbon monoxide, Hydrogen sulphide and hydrogen cyanide Formatted ... •Cancer Formatted ... –The effect is about 20-30 yearsvc Formatted ... –Sources: Formatted ... Benzene →Leukemia (cancer of blood or bone marrow characterized by proliferation of blood cells – especially white blood cells; Formatted ... Chromium, Beryllium and Arsenic Trioxide →Lung Cancer; Formatted ... Asbestos →Larynx, Lung and Abdomen cancer Formatted ... Vinyl Chloride →Liver Cancer; Formatted ... Coal Tar Pitch →Skin Can cer; & Formatted ... Benzidine→Bladder Cancer Formatted ... Formatted ... Formatted ... Formatted ... Formatted ... –Reduce the elasticity of the lung Formatted ... –Sources: Silica, beryllium, asbestos, iron oxide, tin Formatted ... •Reproductive Effect Formatted ... –Causes the inability to reproduce and fetal development Formatted ... Sources: Formatted ... Mercury →Low birth weight; Formatted ... Polychlorinated biphenyls (PCBs) →Brown patches; Formatted ... Lead →Miscarriage; & Formatted ... Formatted ... •Pneumoconiosis – occupational lung disease caused by the inhalation of dust, especially from coal, graphite, or man-made carbon over a long period of time –Dusts retained in the lung X-Rays and Some Pesticides (e.g., 2, 6-di-tert-butyl-p-cresol -DBPC) →Decreased sperm cell and sterility 27 Page 27 of 60 •Systemic Poisons Formatted: Font: Times New Roman, Font color: Auto –Affect more than one organ Formatted: Font: Times New Roman –Sources: Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Cadmium: causes lung irritation; impairs kidney function & may cause sterility Formatted: Font: Times New Roman, No underline, Font color: Auto Mercury: accumulation in the brain causes tremors and mood changes; decreases Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Kidney efficiency; gum inflammation & excess saliva Formatted: Font: Times New Roman Silicosis (also known as Potter's rot) is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in forms of nodular lesions in the upper lobes of the lungs. Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Silicosis (especially the acute form) is characterized by shortness of breath, fever, and cyanosis (bluish skin). It may often be misdiagnosed as pulmonary edema (fluid in the lungs), pneumonia, or tuberculosis. Formatted ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Factors Affecting Toxic Effect Formatted ... Formatted ... Formatted: Font: Times New Roman •Factors related to the agent Formatted –Chemical Composition ... Formatted: Font: Times New Roman Formatted –Physical properties ... Formatted: Font: Times New Roman –Solubility in body fluids Formatted ... Formatted: Font: Times New Roman •Factors related to the Exposure Situation Formatted ... Formatted ... Formatted: Font: Times New Roman –Dose: how much and how long? Formatted ... Formatted: Font: Times New Roman –Co-factors: Presence of other materials Formatted ... Formatted: Font: Times New Roman •Factors related to the individuals Formatted ... Formatted ... Formatted: Font: Times New Roman 28 Page 28 of 60 –Individual differences: genetic status and allergic status Formatted: Font: Times New Roman, No underline, Font color: Auto –Age Formatted: Font: Times New Roman –Presence of predisposing disease: e.g. Angina (Heart Disease) →cannot tolerate carbon monoxide, & Emphysema (lung ailment) Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Font color: Auto Diseases associated with asbestos • • • Asbestosis – lung disease, scar surrounding lung tissue. Impair lung function, 25 – 40 years later. Formatted: Font: Times New Roman Mesithelioma – cancer of outer lining of lung and chest cavity and or lining of abdominal wall, 15 – 30 years later Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Lung cancer and GI cancer, 15 – 30 years later Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman 29 Page 29 of 60 Respiration & Work (C.Winder, Occupational Toxicology 2nd Ed, CRC Press; Edited: C Winder & N Stacey) To appreciate the amount of air that can be inhaled by people at work its necessary to have rough estimates of amount of air a worker might breathe over a day at work: 3 Conservative estimate of 500ml per breath & 15 breaths per minute gives 3.6 m per 8-hr day. 3 Over full day a person breathes 3x the amount giving 10.8m . o Formatted: Font: Times New Roman, Font color: Auto Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Human lung comes in contact with 20kg air per day; along with the air is a chemical & microbiological load. Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Factors affecting deposition of inhaled materials. Formatted: Font: Times New Roman, No underline, Font color: Auto Various factors influence deposition once the material reaches the respiratory system, but many of those factors also depend on what is happening in the particular region of the respiratory system; but these include: air flow rate, particle size, particle density, and solubility in mucus. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Inhalation & exhalation entails variations in air flow rate & direction; this in turn affects absorption (which occurs in all regions of respiration system) and deposition. Absorption also depends on solubility in mucus (important for soluble gases, vapors & particulates). In the upper airways, air flow rate is so high that many inhaled particles are propelled into the lining of the airways where they are absorbed (in the size range 5-30m). This is called inertial impact. Formatted: Font: Times New Roman, No underline, Font color: Auto Further down the system, in bronchi & bronchioles, speed & direction changes are less traumatic and smaller particles (in the size range 1-5m) which were carried down by force respiration begin to drop out of the air flow. This is called sedimentation; depends on gravity. Formatted: Font: Times New Roman, No underline, Font color: Auto Finally, at the end of airways, the terminal bronchioles, and in the gas exchange areas, there is hardly any change in air movement at all, and gases, vapors, and small particles (less than 1m tend to diffuse across a concentration gradient (e.g. O2 in, CO2 out). This is the process of diffusion; requires low air speed. Formatted: Font: Times New Roman, No underline, Font color: Auto Role of the nasal passages’. Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman 30 Page 30 of 60 Nasal passages plays important role when looking at respiration & work interaction: Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Human beings are nose-breathers under normal O2 demand, and air passes thru nasal passages and the mucous linings where it is humidified and removal of particulates as well as soluble gases & vapors also occur. The region thus acts like a filter. Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman When O2 demand increases beyond what can be supplied through the nose, human beings become mouth-breathers. This means bypassing of the nasal passages (the filtering mechanism) in an attempt to get enough air to the lungs. This increases the risk that carry out hard work in contaminated environment. o Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Care should be given to inhalational exposure for workers with heavy workloads. Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Defences: Clearance or retention of inhaled materials Formatted: Font: Times New Roman, No underline, Font color: Auto Mechanisms of clearance or retention of inhaled substances depends on the region of the respiratory system. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto The nasopharyngeal compartment has following mechanisms: Smell/avoidance Formatted: Font: Times New Roman Coarse nose hairs Formatted: Font: Times New Roman, No underline, Font color: Auto Impaction & collection in the nasal turbunines Formatted: Font: Times New Roman, No underline, Font color: Auto Irritation of the nasal epithelium (lining) evoking sneeze Formatted: Font: Times New Roman Some production of mucous. Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted Formatted Cough Irritation of epithelial lining Bronchoconstriction - is the constriction of the airways in the lungs due to the tightening of surrounding smooth muscle resulting from exposure to irritant chemicals, with consequent coughing ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Formatted 31 ... Formatted: Font: Times New Roman Formatted ... Formatted ... Formatted: Font: Times New Roman Page 31 of 60 ... Formatted: Font: Times New Roman Tracheobroncheal compartment has following mechanisms: Mucociliary clearance moves dissolved or suspended material through the respiratory system to the back of the mouth where it can be expectorated (ejected as saliva or mucus) or swallowed. Pulmonary compartment has following mechanisms: Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted Phagocytosis, primarily by alveolar macrophage activity Some drainage of material Formatted ... Formatted: Font: Times New Roman Inevitably some materials are retained by the lung tissue. Formatted ... Formatted: Font: Times New Roman Heavy Metals Formatted ... Formatted: Font: Times New Roman Heavy metals are extremely dense metals found naturally as trace elements. Some examples include mercury (Hg), Lead (Pb), Cadmium (Cd), etc. While some heavy metals are not highly toxic as elements, their cationic states are far more reactive. Formatted ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman The degree of relative toxicity of a given heavy metal can vary with the exact chemical form of the element, including oxidation state. One particularly toxic form involves attachment of alkyl groups which permit passage through the blood-brain barrier. Heavy metals in these states are responsible for immediate, long-term and fetal toxic effects and can cause irreversible damage. Formatted ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Formatted WHO Heavy Metal limits for Drinking Water ... Formatted: Font: Times New Roman ... Formatted: Font: Times New Roman Formatted Heavy Metal Limit (ppb) Hg 1 Cd 3 Pb 10 As 10 ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Formatted ... Formatted: Font: Times New Roman Formatted Mercury, (perhaps more than any other heavy metal) has achieved a high level of notoriety. Mercury poisoning is, and will continue to be a major issue in environmental chemistry for years to come. Industrial production of certain chemicals (eg. NaOH, Cl2) often results in inadvertent / fugitive release of both gaseous and solid amalgams of mercury. Formatted: Font: Times New Roman Formatted Page 32 of 60 ... Formatted: Font: Times New Roman Formatted Formatted: Font: Times New Roman 32 ... Formatted: Font: Times New Roman ... Accumulation and bio-concentration of mercury in fish is a well-publicized concern in many water systems world-wide. Mercury often forms methyl-mercury in aqueous systems, by reacting with light and various organic compounds. Methyl-mercury is of particular concern because of its affinity and persistence in fatty tissues and lipids in humans. Mercury can also enter the ecosystem through leaching from soils/rocks and can be exasperated by activities such as dams (altering water levels) and flooding. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Lead, a soft heavy metal, is now used far less in most western industrialized nations than previously. Previously used in leaded gasolines, many paints and as "shot" for shotgun ammunition, these sources of lead contamination have been banned in countries like Canada. Formatted: Font: Times New Roman, No underline Lead is still a component of certain solders used in electrical wiring and exists as a component of the plumbing in even in such countries as Canadian, especially in older residences. The current major source of lead exposure for most countries including Canada continues to be drinking water. Long term accumulation of lead results in accumulation in the brain, often as a result of numerous years exposure and accumulation. Most vulnerable are fetuses and young children undergoing rapid brain growth/development. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Cadmium, is a by-product of industrial activities (such as zinc production) and is often found in high-power batteries in phones, portable tools and video cameras. When such batteries are incorrectly disposed of, each battery can release as much as several grams of cadmium, particularly a concern during incineration. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Higher levels of cadmium can be found near smelters and mines, but the greatest general human exposure is through diet. Cadmium is absorbed by plants and is consumed by humans and animals. Acute toxicity is high (lethal dose < 1g) but cadmium itself is not biomagnified like mercury. Arsenic, is commonly known as an acute poison but is introduced into the environment through the smelting / mining of metals (nickel/gold, etc.), through the burning of coal and as a component of pesticides. Considerable amounts of arsenic continue to be leached from abandoned gold mines resulting in considerable water contamination. Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman 33 Page 33 of 60 Human intake is largely through drinking water, leading to carcinogenic toxicity, particularly in combination with smoking, although elevated skin cancer has also been associated with chronic exposure to arsenic. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto 34 Page 34 of 60 Formatted: Font: Times New Roman, No underline 3. MONITORING HAZARDOUS SUBSTANCES Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline 3.1 Hazard Surveillance and Survey Methods Formatted: Font: Times New Roman Employment screening programmes if they are used to determine Occupational surveillance involves active programmes to anticipate, observe, measure, evaluate and control exposures to potential health hazards in the workplace. Formatted: Font: Times New Roman, No underline Surveillance often involves a team of people that includes an occupational hygienist, occupational physician, occupational health nurse, safety officer, toxicologist and engineer. Obviously it is not always practical to enlist such a group of workers; however, each person evaluating the work environment must be knowledgeable of the contributions of other professions to the solution of specific problems. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Depending upon the occupational environment and problem, three surveillance methods can be employed: medical, environmental and biological. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Medical surveillance is a planned programme of periodic examination, which may include clinical examination, biological monitoring, or medical testing of employees by an occupational health practitioner or an occupational medical practitioner. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Environmental surveillance is a planned programme of periodic documentation of potential exposure to contaminants for a group of employees, by measuring the concentration of contaminants in the air, in bulk samples of materials, and on surfaces. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Biological surveillance is a planned programme of periodic collection and analysis of body fluid, tissues, and excreta or exhaled air in order to detect and quantify the exposure to or absorption of any substance or organism. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Medical Surveillance Formatted: Font: Times New Roman 35 Page 35 of 60 Is performed because diseases can be caused or exacerbated by exposure to hazardous substances. It requires an active programme with professionals who are knowledgeable about occupational diseases, diagnoses and treatment. Formatted: Font: Times New Roman, No underline Medical surveillance programmes provide steps to protect, educate, monitor and, in some cases, compensate the employee. Formatted: Font: Times New Roman, No underline It can include pre-employment screening programmes, periodic medical examinations, specialized tests to detect early changes and impairment caused by hazardous substances, medical treatment and extensive record keeping. Formatted: Font: Times New Roman, No underline o Formatted: Font: Times New Roman Pre-employment screening involves the evaluation of occupational and medical history questionnaires and results of physical examinations. Questionnaires provide information concerning past illnesses and chronic diseases (especially asthma, skin, lung and heart diseases) and past occupational exposures. There are ethical and legal implications of pre-employment eligibility. However, they are fundamentally important when used to Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman (1) provide a record of previous employment and associated exposures, (2) establish a baseline of health for an employee and Formatted: Font: Times New Roman, No underline (3) Test for hyper-susceptibility. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Medical examinations can include audiometric tests for hearing loss, vision tests, and tests of organ function, evaluation of fitness for wearing respiratory protection equipment, and baseline urine and blood tests. o Periodic medical examinations are essential for evaluating and detecting trends in the onset of adverse health effects and may include biological monitoring for specific contaminants and the use of other biomarkers. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Environmental and Biological Surveillance Formatted: Font: Times New Roman, No underline Environmental and biological surveillance starts with an occupational hygiene survey (normally called the walk-through inspection) of the work environment to identify potential hazards and contaminant sources, and determine the need for monitoring. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline General principles in evaluating the occupational environment Formatted: Font: Times New Roman 36 Page 36 of 60 Formatted: Font: Times New Roman, No underline The general principles in evaluating the occupational environment involves i. Recognition of potential hazards Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline ii. Preparation for field study Formatted: Font: Times New Roman iii. Conducting the field study Formatted: Font: Times New Roman, No underline iv. Interpretation of survey results Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Recognition of potential hazards Formatted: Font: Times New Roman The investigator must become familiar with all processes, chemicals, inter-mediate and byproducts used in the particular plant or establishment. This information is gathered by conducting a walk-through inspection. Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline, Font color: Auto The Walk-Through Inspection The purpose of the walk-through inspection is to systematically gather information to judge whether a potentially hazardous situation exists and whether monitoring is indicated. An occupational hygienist begins the walk-through survey with an opening meeting that can include representatives of management, employees, supervisors, occupational health nurses and union representatives. The occupational hygienist can powerfully impact the success of the survey and any subsequent monitoring initiatives by creating a team of people who communicate openly and honestly with one another and understand the goals and scope of the inspection. Workers must be involved and informed from the beginning to ensure that cooperation, not fear, dominates the investigation. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline During the meeting, requests are made for process flow diagrams, plant layout drawings, past environmental inspection reports, production schedules, equipment maintenance schedules, documentation of personal protection programmes, and statistics concerning the number of employees, shifts and health complaints. All hazardous materials used and produced by an operation are identified and quantified. A chemical inventory of products, by-products, intermediates and impurities is assembled and all associated Material Safety Data Sheets are 37 Page 37 of 60 Formatted: Font: Times New Roman obtained. Equipment maintenance schedules, age and condition are documented because the use of older equipment may result in higher exposures due to the lack of controls. Formatted: Font: Times New Roman After the meeting, the occupational hygienist performs a visual walk-through survey of the workplace, scrutinizing the operations and work practices, with the goal of identifying potential occupational stresses, ranking the potential for exposure, identifying the route of exposure and estimating the duration and frequency of exposure. The occupational hygienist uses the walkthrough inspection to observe the workplace and have questions answered. Formatted: Font: Times New Roman, No underline Examples of observations and questions are given in Fig. 1. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman 38 Page 38 of 60 Formatted: Font: Times New Roman In addition to the questions shown in Fig. 1, questions should be asked that uncover what is not immediately obvious. Questions could address: Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline 1. Non-routine tasks and schedules for maintenance and cleaning activities Formatted: Font: Times New Roman 39 Page 39 of 60 Formatted: Font: Times New Roman, No underline 2. Recent process changes and chemical substitutions Formatted: Font: Times New Roman, No underline 3. Recent physical changes in the work environment Formatted: Font: Times New Roman 4. Changes in job functions Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman 5. Recent renovations and repairs. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Non-routine tasks can result in significant peak exposures to chemicals that are difficult to predict and measure during a typical workday. Formatted: Font: Times New Roman, No underline Process changes and chemical substitutions may alter the release of substances into the air and affect subsequent exposure. Formatted: Font: Times New Roman, No underline Changes in the physical layout of a work area can alter the effectiveness of an existing ventilation system. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman Changes in job functions can result in tasks performed by inexperienced workers and increased exposures. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Renovations and repairs may introduce new materials and chemicals into the work environment which off-gas volatile organic chemicals or are irritants. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline After the walk-through inspection is completed, the occupational hygienist must determine whether sampling is necessary; sampling should be performed only if the purpose is clear. The occupational hygienist must ask, “What will be made of the sampling results and what questions will the results answer?” It is relatively easy to sample and obtain numbers; it is far more difficult to interpret them. Formatted: Font: Times New Roman Preparing and conducting the field survey Formatted: Font: Times New Roman, No underline, Font color: Auto The objective is to determine the intensity of exposure and to do this one must collect samples of the air or use direct reading instruments. Every effort must be made to obtain representative samples. To achieve this sampling strategy must be designed addressing the following questions: Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline What to sample (selection of chemical agents); Formatted: Font: Times New Roman Where to sample (personal, area or source sample); Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman 40 Page 40 of 60 Whom to sample (which worker or group of workers); Formatted: Font: Times New Roman, No underline Sample duration (real-time or integrated); Formatted: Font: Times New Roman How often to sample (how many days); Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman How many samples Formatted: Font: Times New Roman, No underline How to sample, (analytical method). Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Traditionally, sampling performed for regulatory purposes involves brief campaigns (one or two days) that concentrate on worst-case exposures. While this strategy requires a minimum expenditure of resources and time, it often captures the least amount of information and has little applicability to evaluating long-term occupational exposures. To evaluate chronic exposures so that they are useful for occupational physicians and epidemiological studies, sampling strategies must involve repeated sampling over time for large numbers of workers. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman What to sample Most occupational environments have exposures to multiple contaminants. Chemical agents are evaluated both individually and as multiple simultaneous assaults on workers. Chemical agents can act independently within the body or interact in a way that increases the toxic effect. The question of what to measure and how to interpret the results depends upon the biological mechanism of action of the agents when they are within the body. Agents can be evaluated separately if they act independently on altogether different organ systems, such as an eye irritant and a neurotoxin. If they act on the same organ system, such as two respiratory irritants, their combined effect is important. If the toxic effect of the mixture is the sum of the separate effects of the individual components, it is termed additive. If the toxic effect of the mixture is greater than the sum of the effects of the separate agents, their combined effect is termed synergistic. Exposure to cigarette smoking and inhalation of asbestos fibers gives rise to a much greater risk of lung cancer than a simple additive effect. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Sampling all the chemical agents in a workplace would be both expensive and not necessarily defensible. The occupational hygienist must prioritize the laundry list of potential agents by hazard or risk to determine which agents receive the focus. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Factors involved in ranking chemicals include: Formatted: Font: Times New Roman 41 Page 41 of 60 · Whether the agents interact independently, additively or synergistically Formatted: Font: Times New Roman, No underline · Inherent toxicity of the chemical agent Formatted: Font: Times New Roman · Quantities used and generated Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman · Number of people potentially exposed Formatted: Font: Times New Roman, No underline · anticipated duration and concentration of the exposure Formatted: Font: Times New Roman · Confidence in the engineering controls Formatted: Font: Times New Roman, No underline · anticipated changes in the processes or controls Formatted: Font: Times New Roman · Occupational exposure limits and guidelines. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Where to sample Formatted: Font: Times New Roman To provide the best estimate of employee exposure, air samples are taken in the breathing zone of the worker (within a 30 cm radius of the head), and are called personal samples. To obtain breathing zone samples, the sampling device is placed directly on the worker for the duration of the sampling. If air samples are taken near the worker, outside of the breathing zone, they are called area samples. Area samples tend to underestimate personal exposures and do not provide good estimates of inhalation exposure. However, area samples are useful for evaluating contaminant sources and measuring ambient levels of contaminants. Area samples can be taken while walking through the workplace with a portable instrument, or with fixed sampling stations. Area sampling is routinely used at asbestos abatement sites for clearance sampling and for indoor air investigations. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Whom to sample Formatted: Font: Times New Roman, No underline Ideally, to evaluate occupational exposure, each worker would be individually sampled for multiple days over the course of weeks or months. However, unless the workplace is small (<10 employees), it is usually not feasible to sample all the workers. To minimize the sampling burden in terms of equipment and cost, and increase the effectiveness of the sampling programme, a subset of employees from the workplace is sampled, and their monitoring results are used to represent exposures for the larger work force. Formatted: Font: Times New Roman 42 Page 42 of 60 Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman To select employees who are representative of the larger work force, one approach is to classify employees into groups with similar expected exposures, called homogeneous exposure groups (HEGs) (Corn 1985). After the HEGs are formed, a subset of workers is randomly selected from each group for sampling. Methods for determining the appropriate sample sizes assume a lognormal distribution of exposures, an estimated mean exposure, and a geometric standard deviation of 2.2 to 2.5. Prior sampling data might allow a smaller geometric standard deviation to be used. To classify employees into distinct HEGs, most occupational hygienists observe workers at their jobs and qualitatively predict exposures. Formatted: Font: Times New Roman, No underline There are many approaches to forming HEGs; generally, workers may be classified by job task similarity or work area similarity. When both job and work area similarities are used, the method of classification is called zoning (see Fig. 2). Once airborne, chemical and biological agents can have complex and unpredictable spatial and temporal concentration patterns throughout the work environment. Therefore, proximity of the source relative to the employee may not be the best indicator of exposure similarity. Exposure measurements made on workers initially expected to have similar exposures may show that there is more variation between workers than predicted. In these cases, the exposure groups should be reconstructed into smaller sets of workers, and sampling should continue to verify that workers within each group actually have similar exposures (Rappaport 1995). Formatted: Font: Times New Roman, No underline ______________________________________________________________________________ ___ Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman Figure 2. Formatted: Font: Times New Roman, No underline Factors involved in creating HEGs using zoning Formatted: Font: Times New Roman 43 Page 43 of 60 Formatted: Font: Times New Roman ______________________________________________________________________________ __ Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Exposures can be estimated for all the employees, regardless of job title or risk, or it can be estimated only for employees who are assumed to have the highest exposures; this is called worst-case sampling. Formatted: Font: Times New Roman The selection of worst-case sampling employees may be based upon production, proximity to the source, past sampling data, inventory and chemical toxicity. The worst-case method is used for regulatory purposes and does not provide a measure of long-term mean exposure and day-to-day variability. Task-related sampling involves selecting workers with jobs that have similar tasks that occur on a less than daily basis. There are many factors that enter into exposure and can affect the success of HEG classification, including the following: Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman 44 Page 44 of 60 Formatted: Font: Times New Roman, No underline 1. Employees rarely perform the same work even when they have the same job description, and rarely have the same exposures. Formatted: Font: Times New Roman 2. Employee work practices can significantly alter exposure. Formatted: Font: Times New Roman, No underline 3. Workers who are mobile throughout the work area may be unpredictably exposed to several contaminant sources throughout the day. Formatted: Font: Times New Roman 4. Air movement in a workplace can unpredictably increase the exposures of workers who are located a considerable distance from a source. Formatted: Font: Times New Roman 5. Exposures may be determined not by the job tasks but by the work environment. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Sample duration Formatted: Font: Times New Roman, No underline The concentrations of chemical agents in air samples are either measured directly in the field, obtaining immediate results (real-time or grab), or are collected over time in the field on sampling media or in sampling bags and are measured in a laboratory (integrated) (Lynch 1995). The advantage of real-time sampling is that results are obtained quickly onsite, and can capture measurements of short-term acute exposures. However, real-time methods are limited because they are not available for all contaminants of concern and they may not be analytically sensitive or accurate enough to quantify the targeted contaminants. Real-time sampling may not be applicable when the occupational hygienist is interested in chronic exposures and requires time-weighted-average measurements to compare with OELs. Formatted: Font: Times New Roman Real-time sampling is used for emergency evaluations, obtaining crude estimates of concentration, leak detection, ambient air and source monitoring, evaluating engineering controls, monitoring short-term exposures that are less than 15 minutes, monitoring episodic exposures, monitoring highly toxic chemicals (carbon monoxide), explosive mixtures and process monitoring. Real-time sampling methods can capture changing concentrations over time and provide immediate qualitative and quantitative information. Integrated air sampling is usually performed for personal monitoring, area sampling and for comparing concentrations to timeweighted-average with OELs. The advantages of integrated sampling are that methods are available for a wide variety of contaminants; it can be used to identify unknowns; accuracy and specificity is high and limits of detection are usually very low. Formatted: Font: Times New Roman, No underline 45 Page 45 of 60 Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Integrated samples that are analyzed in a laboratory must contain enough contaminant to meet minimum detectable analytical requirements; therefore, samples are collected over a predetermined time period. Formatted: Font: Times New Roman, No underline In addition to analytical requirements of a sampling method, sample duration should be matched to the sampling purpose. For source sampling, duration is based upon the process or cycle time, or when there are anticipated peaks of concentrations. For peak sampling, samples should be collected at regular intervals throughout the day to minimize bias and identify unpredictable peaks. The sampling period should be short enough to identify peaks while also providing a reflection of the actual exposure period. Formatted: Font: Times New Roman, No underline For personal sampling, duration is matched to the occupational exposure limit, task duration or anticipated biological effect. Real-time sampling methods are used for assessing acute exposures to irritants, asphyxiants, sensitizers and allergenic agents. Chlorine, carbon monoxide and hydrogen sulphide are examples of chemicals that can exert their effects quickly and at relatively low concentrations. Formatted: Font: Times New Roman, No underline Chronic disease agents such as lead and mercury are usually sampled for a full shift (seven hours or more per sample), using integrated sampling methods. To evaluate full shift exposures, the occupational hygienist uses either a single sample or a series of consecutive samples that cover the entire shift. The sampling duration for exposures that occur for less than a full shift are usually associated with particular tasks or processes. Construction workers, indoor maintenance personnel and maintenance road crews are examples of jobs with exposures that are tied to tasks. Formatted: Font: Times New Roman, No underline How many samples and how often to sample? Formatted: Font: Times New Roman, No underline Concentrations of contaminants can vary minute to minute, day to day and season to season, and variability can occur between individuals and within an individual. Exposure variability affects both the number of samples and the accuracy of the results. Variations in exposure can arise from different work practices, changes in pollutant emissions, the volume of chemicals used, production quotas, ventilation, temperature changes, worker mobility and task assignments. Most sampling campaigns are performed for a couple of days in a year; therefore, the measurements obtained are not representative of exposure. The period over which samples are collected is very short compared with the unsampled period; the occupational hygienist must extrapolate from the sampled to the unsampled period. For long-term exposure monitoring, each worker selected from a HEG should be sampled multiple times over the course of weeks or Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman 46 Page 46 of 60 Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline months, and exposures should be characterized for all shifts. While the day shift may be the busiest, the night shift may have the least supervision and there may be lapses in work practices. Formatted: Font: Times New Roman Sampling Techniques Formatted: Font: Times New Roman, Not Italic, No underline Sampling equipments are generally classified according to type as follows: (1) direct reading; (2) those that remove the contaminant from a measured quantity of air; and (3) those which collect a known volume of air for subsequent laboratory analysis. Formatted: Font: Times New Roman, Bold, Not Italic Most equipment used by industrial hygienist fall under the first two types. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Active and passive sampling Formatted: Font: Times New Roman, No underline Contaminants are collected on sampling media either by actively pulling an air sample through the media, or by passively allowing the air to reach the media. Active sampling uses a batterypowered pump, and passive sampling uses diffusion or gravity to bring the contaminants to the sampling media. Gases, vapours, particulates and bioaerosols are all collected by active sampling methods; gases and vapours can also be collected by passive diffusion sampling. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman For gases, vapours and most particulates, once the sample is collected the mass of the contaminant is measured, and concentration is calculated by dividing the mass by the volume of sampled air. For gases and vapours, concentration is expressed as parts per million (ppm) or , and for particulates concentration is expressed as Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline (Dinardi 1995). Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman In integrated sampling, air sampling pumps are critical components of the sampling system because concentration estimates require knowledge of the volume of sampled air. Pumps are selected based upon desired flowrate, ease of servicing and calibration, size, cost and suitability for hazardous environments. The primary selection criterion is flowrate: low-flow pumps (0.5 to 500 ml/min) are used for sampling gases and vapours; high-flow pumps (500 to 4,500 ml/min) are used for sampling particulates, bioaerosols and gases and vapours. To insure accurate sample volumes, pumps must be accurately calibrated. Calibration is performed using primary standards such as manual or electronic soap-bubble meters, which directly measure volume, or secondary 47 Page 47 of 60 Formatted: Font: Times New Roman, No underline methods such as wet test meters, dry gas meters and precision rotameters that are calibrated against primary methods. Formatted: Font: Times New Roman Gases and vapours: sampling media Formatted: Font: Times New Roman, No underline Gases and vapours are collected using porous solid sorbent tubes, impingers, passive monitors and bags. Formatted: Font: Times New Roman Sorbent tubes are hollow glass tubes that have been filled with a granular solid that enables adsorption of chemicals unchanged on its surface. Solid sorbents are specific for groups of compounds; commonly used sorbents include charcoal, silica gel and Tenax. Charcoal sorbent, an amorphous form of carbon, is electrically nonpolar, and preferentially adsorbs organic gases and vapours. Silica gel, an amorphous form of silica, is used to collect polar organic compounds, amines and some inorganic compounds. Because of its affinity for polar compounds, it will adsorb water vapour; therefore, at elevated humidity, water can displace the less polar chemicals of interest from the silica gel. Tenax, a porous polymer, is used for sampling very low concentrations of nonpolar volatile organic compounds. Formatted: Font: Times New Roman The ability to accurately capture the contaminants in air and avoid contaminant loss depends upon the sampling rate, sampling volume, and the volatility and concentration of the airborne contaminant. Collection efficiency of solid sorbents can be adversely affected by increased temperature, humidity, flowrate, concentration, sorbent particle size and number of competing chemicals. As collection efficiency decreases chemicals will be lost during sampling and concentrations will be underestimated. To detect chemical loss, or breakthrough, solid sorbent tubes have two sections of granular material separated by a foam plug. The front section is used for sample collection and the back section is used to determine breakthrough. Breakthrough has occurred when at least 20 to 25% of the contaminant is present in the back section of the tube. Analysis of contaminants from solid sorbents requires extraction of the contaminant from the medium using a solvent. For each batch of sorbent tubes and chemicals collected, the laboratory must determine the desorption efficiency, the efficiency of removal of chemicals from the sorbent by the solvent. For charcoal and silica gel, the most commonly used solvent is carbon disulphide. For Tenax, the chemicals are extracted using thermal desorption directly into a gas chromatograph. Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, Bold, Italic, No underline Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, Bold, Italic, No underline Formatted: Font: Times New Roman, Bold, Italic, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Bold, Italic, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Bold, Italic, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Bold, Italic, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Impingers are usually glass bottles with an inlet tube that allows air to be drawn into the bottle through a solution that collects the gases and vapours by absorption either unchanged in solution or by a chemical reaction. Impingers are used less and less in workplace monitoring, especially for personal sampling, because they can break, and the liquid media can spill onto the employee. There are a variety of types of impingers, including gas wash bottles, spiral absorbers, glass bead columns, midget impingers and fritted bubblers. All impingers can be used to collect area 48 Page 48 of 60 Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline samples; the most commonly used impinger, the midget impinger, can be used for personal sampling as well. Formatted: Font: Times New Roman Passive, or diffusion monitors are small, have no moving parts and are available for both organic and inorganic contaminants. Most organic monitors use activated charcoal as the collection medium. In theory, any compound that can be sampled by a charcoal sorbent tube and pump can be sampled using a passive monitor. Each monitor has a uniquely designed geometry to give an effective sampling rate. Sampling starts when the monitor cover is removed and ends when the cover is replaced. Most diffusion monitors are accurate for eight-hour time-weighted-average exposures and are not appropriate for short-term exposures. Formatted: Font: Times New Roman, No underline Sampling bags can be used to collect integrated samples of gases and vapours. They have permeability and adsorptive properties that enable storage for a day with minimal loss. Bags are made of Teflon (polytetrafluoroethylene) and Tedlar (polyvinylfluoride). Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Sampling media: particulate materials Formatted: Font: Times New Roman, No underline Occupational sampling for particulate materials, or aerosols, is currently in a state of flux; traditional sampling methods are being replaced by particle size selective (PSS) sampling methods. Traditional sampling methods will be discussed first, followed by PSS methods. Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Italic, No underline Traditional Sampling methods: The most commonly used media for collecting aerosols are fibre or membrane filters; aerosol removal from the air stream occurs by collision and attachment of the particles to the surface of the filters. The choice of filter medium depends upon the physical and chemical properties of the aerosols to be sampled, the type of sampler and the type of analysis. When selecting filters, they must be evaluated for collection efficiency, pressure drop, hygroscopicity, background contamination, strength and pore size, which can range from 0.01 to 10 mm. Membrane filters are manufactured in a variety of pore sizes and are usually made from cellulose ester, polyvinylchloride or polytetrafluoroethylene. Particle collection occurs at the surface of the filter; therefore, membrane filters are usually used in applications where microscopy will be performed. Mixed cellulose ester filters can be easily dissolved with acid and are usually used for collection of metals for analysis by atomic absorption (AAS). Nucleopore filters (polycarbonate) are very strong and thermally stable, and are used for sampling and analysing asbestos fibres using transmission electron microscopy (TEM). Fibre filters are usually made of fibreglass and are used to sample aerosols such as pesticides and lead. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman 49 Page 49 of 60 For occupational exposures to aerosols, a known volume of air can be sampled through the filters, the total increase in mass (gravimetric analysis) can be measured (mg/m(3) air), the total number of particles can be counted (fibres/cc) or the aerosols can be identified (chemical analysis). For mass calculations, the total dust that enters the sampler or only the respirable fraction can be measured. For total dust (sum of insipirable and non-insiperable fraction), the increase in mass represents exposure from deposition in all parts of the respiratory tract. Total dust samplers are subject to error due to high winds passing across the sampler and improper orientation of the sampler. High winds, and filters facing upright, can result in collection of extra particles and overestimation of exposure. Formatted: Font: Times New Roman, Bold, No underline For respirable dust sampling, the increase in mass represents exposure from deposition in the gas exchange (alveolar) region of the respiratory tract. To collect only the respirable fraction, a preclassifier called a cyclone is used to alter the distribution of airborne dust presented to the filter. Aerosols are drawn into the cyclone, accelerated and whirled, causing the heavier particles to be thrown out to the edge of the air stream and dropped to a removal section at the bottom of the cyclone. The respirable particles that are less than 10 mm remain in the air stream and are drawn up and collected on the filter for subsequent gravimetric analysis. Formatted: Font: Times New Roman, Bold, No underline Sampling errors encountered when performing total and respirable dust sampling result in measurements that do not accurately reflect exposure or relate to adverse health effects. Therefore, PSS has been proposed to redefine the relationship between particle size, adverse health impact and sampling method. In PSS sampling, the measurement of particles is related to the sizes that are associated with specific health effects. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, Bold, No underline The International Organization for Standardization (ISO) and the ACGIH have proposed three particulate mass fractions: inhalable particulate mass (IPM), thoracic particulate mass (TPM) and respirable particulate mass (RPM). Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman IPM refers to particles that can be expected to enter through the nose and mouth, and would replace the traditional total mass fraction. TPM refers to particles that can penetrate the upper respiratory system past the larynx μm<aerodynamic diameter<20 μm; cut size 10 μm). Formatted: Font: Times New Roman, Bold, No underline (7 Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman RPM refers to particles that are capable of depositing in the gas-exchange region of the lung, and would replace the current respirable mass fraction (aerodynamic diameter < 7 μm; cut size 4 μm). Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman A number of PSS samplers are now commercially available. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman 50 Page 50 of 60 Note: The nasal passages are the first line of defense and will trap all particles with an aerodynamic diameter > 7 μm. The nose is less effective in preventing particles less than 7 μm entering the lungs and the lung defenses can still prevent particles reaching the airway walls in the tracheobronchial tree. However, approximately 30% of inspired particles in the range 1-3 μm will be deposited in the lung tissue. Formatted: Font: Times New Roman, No underline Aerodynamic diameter is equal to the diameter of spherical particles of unit density which have the same falling velocity in air as the particle in question. However, asbestos fibres are characterized by their length. Formatted: Font: Times New Roman, No underline Sampling media: biological materials Formatted: Font: Times New Roman, No underline There are few standardized methods for sampling biological material or bioaerosols. Although sampling methods are similar to those used for other airborne particulates, viability of most bioaerosols must be preserved to ensure laboratory culturability. Therefore, they are more difficult to collect, store and analyse. The strategy for sampling bioaerosols involves collection directly on semisolid nutrient agar or plating after collection in fluids, incubation for several days and identification and quantification of the cells that have grown. The mounds of cells that have multiplied on the agar can be counted as colony-forming units (CFU) for viable bacteria or fungi, and plaque-forming units (PFU) for active viruses. With the exception of spores, filters are not recommended for bioaerosol collection because dehydration causes cell damage. Formatted: Font: Times New Roman Viable aerosolized micro-organisms are collected using all-glass impingers (AGI-30), slit samplers and inertial impactors. Impingers collect bioaerosols in liquid and the slit sampler collects bioaerosols on glass slides at high volumes and flowrates. The impactor is used with one to six stages, each containing a Petri dish, to allow for separation of particles by size. Formatted: Font: Times New Roman, No underline Interpretation of sampling results must be done on a case-by-case basis because there are no occupational exposure limits. Evaluation criteria must be determined prior to sampling; for indoor air investigations, in particular, samples taken outside of the building are used as a background reference. A rule of thumb is that concentrations should be ten times background to suspect contamination. When using culture plating techniques, concentrations are probably underestimated because of losses of viability during sampling and incubation. Formatted: Font: Times New Roman, No underline Skin and surface sampling Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, Bold, Italic, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman 51 Page 51 of 60 Formatted: Font: Times New Roman, No underline There are no standard methods for evaluating skin exposure to chemicals and predicting dose. Surface sampling is performed primarily to evaluate work practices and identify potential sources of skin absorption and ingestion. Two types of surface sampling methods are used to assess dermal and ingestion potential: direct methods, which involve sampling the skin of a worker, and indirect methods, which involve wipe sampling surfaces. Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Direct skin sampling involves placing gauze pads on the skin to absorb chemicals, rinsing the skin with solvents to remove contaminants and using fluorescence to identify skin contamination. Gauze pads are placed on different parts of the body and are either left exposed or are placed under personal protective equipment. At the end of the workday the pads are removed and are analysed in the laboratory; the distribution of concentrations from different parts of the body are used to identify skin exposure areas. This method is inexpensive and easy to perform; however, the results are limited because gauze pads are not good physical models of the absorption and retention properties of skin, and measured concentrations are not necessarily representative of the entire body. Formatted: Font: Times New Roman, No underline Skin rinses involve wiping the skin with solvents or placing hands in plastic bags filled with solvents to measure the concentration of chemicals on the surface. This method can underestimate dose because only the unabsorbed fraction of chemicals is collected. Formatted: Font: Times New Roman, Bold, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Fluorescence monitoring is used to identify skin exposure for chemicals that naturally fluoresce, such as polynuclear aromatics, and to identify exposures for chemicals in which fluorescent compounds have been intentionally added. The skin is scanned with an ultraviolet light to visualize contamination. This visualization provides workers with evidence of the effect of work practices on exposure; research is underway to quantify the fluorescence intensity and relate it to dose. Formatted: Font: Times New Roman, Bold, No underline Indirect wipe sampling methods involve the use of gauze, glass fibre filters or cellulose paper filters, to wipe the insides of gloves or respirators, or the tops of surfaces. Solvents may be added to increase collection efficiency. The gauze or filters are then analysed in the laboratory. To standardize the results and enable comparison between samples, a square template is used to Formatted: Font: Times New Roman, No underline sample a Formatted: Font: Times New Roman, No underline area. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman 52 Page 52 of 60 Biological media Formatted: Font: Times New Roman, No underline Blood, urine and exhaled air samples are the most suitable specimens for routine biological monitoring, while hair, milk, saliva and nails are less frequently used. Biological monitoring is performed by collecting bulk blood and urine samples in the workplace and analysing them in the laboratory. Exhaled air samples are collected in Tedlar bags, specially designed glass pipettes or sorbent tubes, and are analysed in the field using direct-reading instruments, or in the laboratory. Blood, urine and exhaled air samples are primarily used to measure the unchanged parent compound (same chemical that is sampled in workplace air), its metabolite or a biochemical change (intermediate) that has been induced in the body. For example, the parent compound lead is measured in blood to evaluate lead exposure, the metabolite mandelic acid is measured in urine for both styrene and ethyl benzene, and carboxyhaemoglobin is the intermediate measured in blood for both carbon monoxide and methylene chloride exposure. Formatted: Font: Times New Roman For exposure monitoring, the concentration of an ideal determinant will be highly correlated with intensity of exposure. For medical monitoring, the concentration of an ideal determinant will be highly correlated with target organ concentration. Formatted: Font: Times New Roman, No underline The timing of specimen collection can impact the usefulness of the measurements; samples should be collected at times which most accurately reflect exposure. Timing is related to the excretion biological half-life of a chemical, which reflects how quickly a chemical is eliminated from the body; this can vary from hours to years. Target organ concentrations of chemicals with short biological half-lives closely follow the environmental concentration; target organ concentrations of chemicals with long biological half-lives fluctuate very little in response to environmental exposures. For chemicals with short biological half-lives, less than three hours, a sample is taken immediately at the end of the workday, before concentrations rapidly decline, to reflect exposure on that day. Samples may be taken at any time for chemicals with long half-lives, such as polychlorinated biphenyls and lead. Formatted: Font: Times New Roman, No underline Measurement Techniques Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman Real-time monitors Formatted: Font: Times New Roman, No underline Direct-reading instruments provide real-time quantification of contaminants; the sample is analysed within the equipment and does not require off-site laboratory analysis (Maslansky and Maslansky 1993). Compounds can be measured without first collecting them on separate media, then shipping, storing and analysing them. Concentration is read directly from a meter, display, strip chart recorder and data logger, or from a colour change. Direct-reading instruments are Formatted: Font: Times New Roman 53 Page 53 of 60 Formatted: Font: Times New Roman, No underline primarily used for gases and vapours; a few instruments are available for monitoring particulates. Instruments vary in cost, complexity, reliability, size, sensitivity and specificity. They include simple devices, such as colorimetric tubes, that use a colour change to indicate concentration; dedicated instruments that are specific for a chemical, such as carbon monoxide indicators, combustible gas indicators (explosimeters) and mercury vapour meters; and survey instruments, such as infrared spectrometers, that screen large groups of chemicals. Direct-reading instruments use a variety of physical and chemical methods to analyse gases and vapours, including conductivity, ionization, potentiometry, photometry, radioactive tracers and combustion. Formatted: Font: Times New Roman Commonly used portable direct-reading instruments include battery-powered gas chromatographs, organic vapour analysers and infrared spectrometers. Gas chromatographs and organic vapour monitors are primarily used for environmental monitoring at hazardous waste sites and for community ambient air monitoring. Gas chromatographs with appropriate detectors are specific and sensitive, and can quantify chemicals at very low concentrations. Organic vapour analysers are usually used to measure classes of compounds. Portable infrared spectrometers are primarily used for occupational monitoring and leak detection because they are sensitive and specific for a wide range of compounds. Formatted: Font: Times New Roman, No underline Small direct-reading personal monitors are available for a few common gases (chlorine, hydrogen cyanide, hydrogen sulphide, hydrazine, oxygen, phosgene, sulphur dioxide, nitrogen dioxide and carbon monoxide). They accumulate concentration measurements over the course of the day and can provide a direct readout of time-weighted-average concentration as well as provide a detailed contaminant profile for the day. Formatted: Font: Times New Roman, No underline Colorimetric tubes (detector tubes) are simple to use, cheap and available for a wide variety of chemicals. They can be used to quickly identify classes of air contaminants and provide ballpark estimates of concentrations that can be used when determining pump flow rates and volumes. Colorimetric tubes are glass tubes filled with solid granular material which has been impregnated with a chemical agent that can react with a contaminant and create a colour change. After the two sealed ends of a tube are broken open, one end of the tube is placed in a hand pump. The recommended volume of contaminated air is sampled through the tube by using a specified number of pump strokes for a particular chemical. A colour change or stain is produced on the tube, usually within two minutes, and the length of the stain is proportional to concentration. Some colorimetric tubes have been adapted for long duration sampling, and are used with batterypowered pumps that can run for at least eight hours. The colour change produced represents a time-weighted-average concentration. Colorimetric tubes are good for both qualitative and 54 Formatted: Font: Times New Roman, No underline Page 54 of 60 Formatted: Font: Times New Roman Formatted: Font: Times New Roman quantitative analysis; however, their specificity and accuracy is limited. The accuracy of colorimetric tubes is not as high as that of laboratory methods or many other real-time instruments. There are hundreds of tubes, many of which have cross-sensitivities and can detect more than one chemical. This can result in interferences that modify the measured concentrations. Formatted: Font: Times New Roman Direct-reading aerosol monitors cannot distinguish between contaminants, are usually used for counting or sizing particles, and are primarily used for screening, not to determine TWA or acute exposures. Real-time instruments use optical or electrical properties to determine total and respirable mass, particle count and particle size. Light-scattering aerosol monitors, or aerosol photometers, detect the light scattered by particles as they pass through a volume in the equipment. As the number of particles increases, the amount of scattered light increases and is proportional to mass. Light-scattering aerosol monitors cannot be used to distinguish between particle types; however, if they are used in a workplace where there are a limited number of dusts present, the mass can be attributed to a particular material. Fibrous aerosol monitors are used to measure the airborne concentration of particles such as asbestos. Fibres are aligned in an oscillating electric field and are illuminated with a helium neon laser; the resulting pulses of light are detected by a photomultiplier tube. Light-attenuating photometers measure the extinction of light by particles; the ratio of incident light to measured light is proportional to concentration. Formatted: Font: Times New Roman, No underline Laboratory Analytical Techniques Formatted: Font: Times New Roman, No underline There are many available methods for analysing laboratory samples for contaminants. Some of the more commonly used techniques for quantifying gases and vapours in air include gas chromatography, mass spectrometry, atomic absorption, infrared and UV spectroscopy and polarography. Formatted: Font: Times New Roman Gas chromatography is a technique used to separate and concentrate chemicals in mixtures for subsequent quantitative analysis. There are three main components to the system: the sample injection system, a column and a detector. A liquid or gaseous sample is injected using a syringe, into an air stream that carries the sample through a column where the components are separated. The column is packed with materials that interact differently with different chemicals, and slows down the movement of the chemicals. The differential interaction causes each chemical to travel through the column at a different rate. After separation, the chemicals go directly into a detector, such as a flame ionization detector (FID), photo-ionization detector (PID) or electron capture detector (ECD); a signal proportional to concentration is registered on a chart recorder. The FID is used for almost all organics including: aromatics, straight chain hydrocarbons, ketones and some chlorinated hydrocarbons. Concentration is measured by the increase in the number of ions produced as a volatile hydrocarbon is burned by a hydrogen flame. The PID is used for organics 55 Formatted: Font: Times New Roman, Bold, No underline Page 55 of 60 Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline and some inorganics; it is especially useful for aromatic compounds such as benzene, and it can detect aliphatic, aromatic and halogenated hydrocarbons. Concentration is measured by the increase in the number of ions produced when the sample is bombarded by ultraviolet radiation. The ECD is primarily used for halogen-containing chemicals; it gives a minimal response to hydrocarbons, alcohols and ketones. Concentration is measured by the current flow between two electrodes caused by ionization of the gas by radioactivity. Formatted: Font: Times New Roman The mass spectrophotometer is used to analyse complex mixtures of chemicals present in trace amounts. It is often coupled with a gas chromatograph for the separation and quantification of different contaminants. Formatted: Font: Times New Roman, No underline Atomic absorption spectroscopy is primarily used for the quantification of metals such as mercury. Atomic absorption is the absorption of light of a particular wavelength by a free, ground-state atom; the quantity of light absorbed is related to concentration. The technique is highly specific, sensitive and fast, and is directly applicable to approximately 68 elements. Detection limits are in the sub-ppb to low-ppm range. Formatted: Font: Times New Roman, No underline Infrared analysis is a powerful, sensitive, specific and versatile technique. It uses the absorption of infrared energy to measure many inorganic and organic chemicals; the amount of light absorbed is proportional to concentration. The absorption spectrum of a compound provides information enabling its identification and quantification. Formatted: Font: Times New Roman, No underline UV absorption spectroscopy is used for analysis of aromatic hydrocarbons when interferences are known to be low. The amount of absorption of UV light is directly proportional to concentration. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman Polarographic methods are based upon the electrolysis of a sample solution using an easily polarized electrode and a nonpolarizable electrode. They are used for qualitative and quantitative analysis of aldehydes, chlorinated hydrocarbons and metals. 56 Page 56 of 60 Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Interpretation of Results Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Occupational exposure limits Formatted: Font: Times New Roman Air and biological sampling data are usually compared to recommend or mandated occupational exposure limits (OELs). Occupational exposure limits have been developed in many countries for inhalation and biological exposure to chemical and physical agents. Formatted: Font: Times New Roman, No underline The philosophical bases for the limits are determined by the organizations that have developed them. The most widely used limits, called threshold limit values (TLVs), areand are those issued in the United States by the American Conference of Governmental Industrial Hygienists (ACGIH). Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman For airborne exposures, there are three types of TLVs: Formatted: Font: Times New Roman, No underline an eight-hour time-weighted-average exposure, TLV-TWA, to protect against chronic health effects; Formatted: Font: Times New Roman a fifteen-minute average short-term exposure limit, TLV-STEL, to protect against acute health effects; Formatted: Font: Times New Roman and an instantaneous ceiling value, TLV-C, to protect against asphyxiants or chemicals that are immediately irritating. Formatted: Font: Times New Roman Guidelines for biological exposure levels are called biological exposure indices (BEIs). These guidelines represent the concentration of chemicals in the body that would correspond to inhalation exposure of a healthy worker at a specific concentration in air. Outside of the United States as many as 50 countries or groups have established OELs, many of which are identical to the TLVs. In Britain, the limits are called the Health and Safety Executive Occupational Exposure Standards (OES), and in Germany OELs are called Maximum Workplace Concentrations (MAKs). Formatted: Font: Times New Roman OELs have been set for airborne exposures to gases, vapours and particulates; they do not exist for airborne exposures to biological agents. Therefore, most investigations of bioaerosol exposure compare indoor with outdoor concentrations. If the indoor/outdoor profile and concentration of organisms is different, an exposure problem may exist. Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman, No underline 57 Page 57 of 60 Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman Formatted: Font: Times New Roman There are no OELs for skin and surface sampling, and each case must be evaluated separately. In the case of surface sampling, concentrations are usually compared with acceptable background concentrations that were measured in other studies or were determined in the current study. For skin sampling, acceptable concentrations are calculated based upon toxicity, rate of absorption, amount absorbed and total dose. In addition, biological monitoring of a worker may be used to investigate skin absorption. Formatted: Font: Times New Roman, No underline Formulas Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Occupational exposure limits Formatted: Font: Times New Roman Ti C i T1C1 T2 C 2 ..... Tn C n T1 T2 .... Tn i 1 Ti TLV TWA Formatted: Font: Times New Roman Ti - time interval Formatted: Font: Times New Roman, No underline, Font color: Auto n C i - concentration value that existed during the i th time interval (Note : any time interval can be used) Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman TWA1 TWA2 n TWAi TWAn % REL 100 ........ 100 REL n i 1 REL i REL1 REL 2 Formatted: Font: Times New Roman %REL gives the effective combined effects of all potentially irritating toxic or hazardous components in any ambient air system. Any established parameter e.g. MAK, TLV, PEL may be used as the REL and this standard needs to be known Formatted: Font: Times New Roman, No underline, Font color: Auto If %REL≤100 then it can be inferred that the effective REL for the mixture as a whole has not been exceeded and vice-versa. Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman 58 Page 58 of 60 TLV effective 1 n fi TLV i i 1 1 fn f2 f1 TLV TLV .... TLV 1 2 n Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto f i - weight fraction of i th component Formatted: Font: Times New Roman, No underline, Font color: Auto TLV i - established OEL of i th component in mg/m3 not ppm Formatted: Font: Times New Roman TLV effective - effective TLV (mg/m3 NOT ppm) for any established exposure limit Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman, No underline, Font color: Auto The above equation is used to determine the effective exposure limit that exists for any equilibrium vapour phase that is in contact with any well defined liquid mixture containing 2 or more different volatile components. Formatted: Font: Times New Roman The value of the exposure limit standard for each component in the liquid mixture must be known. Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman This formula assumes that the overall composition of the vapour phase is identical to that of the liquid phase, although this would rarely –if ever- be true. However the equation is still considered a useful tool for evaluating certain vapour mixtures. Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline, Font color: Auto Formatted: Font: Times New Roman Conversion of concentration units Formatted: Font: Times New Roman, No underline Formatted: Font: Times New Roman C vol ( ppmv ) C vol ( ppmv ) Formatted: Font: Times New Roman, No underline 24.45 C mass (mg / m 3 ) @ NTP (1 atm and 25 oC) MWi 22.41 C mass (mg / m 3 ) MWi Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline @ STP (1 atm and 0 oC) Formatted: Font: Times New Roman Formatted: Font: Times New Roman, No underline Note: The common practice among hygienists is to assume that air samples taken in normal factory air are at NTP. Formatted: Font: Times New Roman 59 Page 59 of 60 Formatted: Font: Times New Roman, No underline Sampling particulates Formatted: Font: Times New Roman Minimum volume of air sample 10 analytical sensitivity hygiene standard concentration Minimum sampling duration per sample Formatted: Font: Times New Roman 10 analytical sensitivity hygiene standard concentration flowrate of sampler Formatted: Font: Times New Roman Minimum duration of sampling 0.01 weight of paper hygiene standard concentration flowrate of sampler Formatted: Font: Times New Roman Formatted: Font: Times New Roman TLV (mg/m 3 ) weight of paper (mg) 10 volume of sample (l) Formatted: Font: Times New Roman, No underline Note: In all the above formulas units must be consistent Formatted: Font: Times New Roman 60 Page 60 of 60