University of the Sciences
Environmental Health & Radiation Safety Department
Quick Guide to Risk Assessment for Toxicity, Physical, Flammable, Explosive
and Reactive Hazards in the Laboratory
The following outline provides a summary of the steps that trained laboratory personnel should
use to assess the risks of handling toxic chemicals and managing physical hazards in the
laboratory.
Identify chemicals to be used and circumstances of use.
Identify the chemicals involved in the proposed experiment and determine the
amounts that will be used. Is the experiment to be done once, or will the
chemicals be handled repeatedly? Will the experiment be conducted in an open
laboratory, in an enclosed apparatus, or in a chemical fume hood? Is it possible
that new or unknown substances will be generated in the experiment? Are any
of the trained laboratory personnel involved in the experiment pregnant or likely
to become pregnant? Do they have any known sensitivities to specific
chemicals?
Consult sources of information.
Consult an up-to-date Safety Data Sheet (SDS) for each chemical involved in the
planned experiment. In cases where substances with significant or unusual
potential hazards are involved, consult more detailed references such as those
listed under Resources at the end of this document. Depending on the laboratory
personnel’s level of experience and the degree of potential hazard associated
with the proposed experiment, obtain the assistance of supervisors and safety
professionals
before
proceeding
with
the
risk
assessment.
Evaluate type of toxicity, or physical, flammable, explosive, or reactive hazards
posed by the chemicals.
Use the below Resources of information at the end of this document and/or
SDS’s to determine the type of toxicity or determine the hazards associated with
each chemical involved in the proposed experiment. Are any of the chemicals to
be used acutely toxic or corrosive? Are any of the chemicals to be used irritants
or sensitizers? Are any of the chemicals to be used flammable or explosive or
are they strong oxidizers? Will any select carcinogens or possibly carcinogenic
substances be encountered? Also, consult the listing of the Resources to identify
chemical similarities to known carcinogens. Are any chemicals involved in the
proposed experiment suspected to be reproductive or developmental toxins or
neurotoxins?
University of the Sciences
Environmental Health & Radiation Safety Department
Consider possible routes of exposure.
Determine the potential routes of exposure for each chemical. Are the chemicals
gases, or are they volatile enough to present a significant risk of exposure
through inhalation? If liquid, can the substances be absorbed through the skin?
Is it possible that dusts or aerosols will be formed in the experiment? Does the
experiment involve a significant risk of inadvertent ingestion or injection of
chemicals?
Evaluate the hazards posed by the chemical changes over the course of the
experiment.
Consider the changes in pressure, heat, flammability, and explosivity during the
experiment. If the experiment is a scale-up of a reaction, consider how changes
in gas production and temperature may change the engineering controls required
for safety.
Evaluate quantitative information on toxicity.
Consult the SDS or the Resources below to determine the LD50 for each
chemical via the relevant routes of exposure. Determine the acute toxicity
hazard level for each substance, classifying each chemical as highly toxic,
moderately toxic, slightly toxic, and so forth. Reference Table 1 and 2 below.
For substances that pose inhalation hazards, take note of the threshold limit
value-time weighted average (TLV-TWA), short-term exposure limit, and
permissible exposure limit values. These values are available in the Safety Data
Sheets.
Table 1. Acute Toxicity Hazard Level
Hazard
Level
High
Medium
Low
Toxicity
Rating
Highly Toxic
Moderately Toxic
Slightly Toxic
Oral LD50
(rats, per kg)
<50 mg
50 to 500 mg
500 mg to 5 g
Skin Contact LD50
(rabbits, per kg)
<200 mg
200 mg to 1 g
1 to 5 g
Inhalation LC50
(rats, ppm for 1 h)
<200
200 to 2,000
2,000 to 20,000
Inhalation LC50
(rats, mg/m3 for 1 h)
<2,000
2,000 to 20,000
20,000 to 200,000
Table 2. Probable Lethal Dose for Humans
Toxicity Rating
Extremely toxic
Highly toxic
Moderately toxic
Slightly toxic
Practically non-toxic
Animal LD50
(per kg)
<5 mg
5 to 50 mg
50 to 500 mg
500 mg to 5 g
>5 g
Lethal Dose When Ingested
by 70-kg (150-lb) Human
A taste (< 7 drops)
Between 7 drops and 1 tsp
Between 1 tsp and 1 oz
Between 1 oz and 1 pint
>1 pint
University of the Sciences
Environmental Health & Radiation Safety Department
Evaluate type of physical hazard(s) posed by the equipment required.
Review procedures for correct use of all equipment. Identify heat and ignition
sources and consider appropriate placement for them in the laboratory. Are any
pieces of equipment going to be under high or low pressure (e.g., a vacuum
line)? Is the glassware free of cracks and chips?
Select appropriate procedures to minimize exposure and risk.
Use the basic prudent safety practices for handling chemicals, which are
discussed in our Laboratory Safety Manual and the linked reference Prudent
Practices in the Laboratory (under Resources) for all work with chemicals in the
laboratory. In addition, for guidance on using laboratory equipment reference
Prudent Practices in the Laboratory, Chapter 7 and the Laboratory Safety
Manual. Further, determine whether any of the chemicals to be handled in the
planned experiment meet the definition of a particularly hazardous substance
due to high acute toxicity, carcinogenicity, and/or reproductive toxicity. If so,
consider the total amount of the substance that will be used, the expected
frequency of use, the chemical’s routes of exposure, and the circumstances of its
use in the proposed experiment. Use this information to determine whether it is
appropriate to apply the additional procedures for work with highly toxic
substances referenced in Prudent Practices in the Laboratory, Chapter 6, section
6.D and our Laboratory Safety Manual, and whether additional consultation with
safety professionals is warranted.
Determine if the chemicals or equipment in use pose physical hazards to
laboratory personnel. If so, consider methods to minimize the risk posed by the
hazard through substitution with another chemical, if possible, or use of
engineering controls (e.g., chemical fume hoods, grounding cables, inert
atmospheres) and personal protective equipment, if not. Use information
referenced in Prudent Practices in the Laboratory, Chapter 7, Chapter 4 and
section 4.D and our Laboratory Safety Manual to determine whether it is
appropriate to apply the additional procedures before continuing work and
whether additional consultation with safety professionals is warranted.
Prepare for contingencies.
Note the signs and symptoms of exposure to the chemicals to be used in the
proposed experiment. Note appropriate measures to be taken in the event of
exposure or accidental release of any of the chemicals, including first aid or
containment actions.
University of the Sciences
Environmental Health & Radiation Safety Department
In addition, be aware of University procedures in the event of emergencies and
accidents. Some questions to consider are: What are the appropriate measures
to take in the event of fire, explosion, or injury? What are the appropriate first-aid
procedures in the event of heat, cold, or chemical burns? What is the procedure
in the event of an emergency or non-emergency spill of the chemical(s)?
Resources for your risk assessment:
1. Prudent Practices in the Laboratory, Handling and Management of Chemical
Hazards (http://www.nap.edu/catalog.php?record_id=4911)
(An authoritative reference on laboratory handling and disposal of hazardous
substances, culture of laboratory safety, hazard and risk evaluation, emergency
planning, laboratory security, safety management systems, handling of nanomaterials
and laboratory operations relative to safety, health and environmental protection)
2. NIOSH Databases and Information Resources (http://www.cdc.gov/niosh)
(Environmental health and safety information)
3. TOXNET through the National Library of Medicine (http://www.nlm.nih.gov)
(On-line database that accesses journals and other resources for toxicological
information on drugs and chemicals)
4. International Chemical Safety Cards from the International Programme on
Chemical Safety (IPCS, 2009) (http://www.cdc.gov/niosh) or (http://www.ilo.org)
(Hazard and exposure information)
5. NIOSH Pocket Guide to
(http://www.cdc.gov/niosh)
Chemical
Hazards
(HHS/CDC/NIOSH,
2007)
(Chemical properties, reactivities, exposure routes and limits, and first-aid measures)
6. Occupational Health Guidelines for Chemical Hazards (HHS/CDC/NIOSH, 1981)
and a supplement (HHS/CDC/NIOSH, 1995) (http://www.cdc.gov/niosh)
(Information on physical, chemical and toxicological properties, signs and symptoms of
exposure, control measures and emergency first-aid procedures)
7. A Comprehensive Guide to the Hazardous Properties of Chemical Substances,
3rd edition (Patnaik, 2007)
(Uses and exposure risks, physical properties, health hazards, exposure limits, fire and
explosion hazards, and disposal and destruction)
University of the Sciences
Environmental Health & Radiation Safety Department
8. 2009 TLVs and BEIs: Based on the Documentation of the Threshold Limit Values
for Chemical Substances and Physical Agents and Biological Exposure Indices
(ACGIH, 2009)
(Threshold limit values (TLVs) and short-term exposure limits (STELs)
9. Fire Protection for Laboratories Using Chemicals (NFPA, 2004)
(Fire safety code pertaining to laboratory use of chemicals)
10. Fire Protection Guide to Hazardous Materials, 13th edition (NFPA, 2001)
(Hazard data on chemicals and guidance on handling and storage of, and emergency
procedures, for those chemicals)
11. Bretherick’s Handbook of Reactive Chemical Hazards, 7th edition (Urben, 2007)
(Examples of violent reactions, fires and explosions due to unstable chemicals and
information on incompatibility between reactive chemicals)
12. Hazardous Chemicals Handbook, 2nd edition (Carson and Mumford, 2002)
(Chemical hazards and synthesizes technical guidance in chemical safety)
13. Sax’s Dangerous Properties of Industrial Materials, 11th edition, three volumes
(Lewis, 2004)
(Much of the information is found in a typical SDS, including physical and chemical
properties, data on toxicity, flammability, reactivity, symptoms of exposure, etc.)
14. Patty’s Industrial Toxicology, 5th edition (Bingham et al., 2001)
(Toxicology of different classes of organic and inorganic compounds, focuses on health
effects)
15. Proctor and Hughes’ Chemical Hazards of the Workplace, 5th edition (Hathaway
and Proctor, 2004)
(Toxicology of chemicals, including signs and symptoms of exposure, and references to
clinical reports)
16. Sittig’s Handbook of Toxic and Hazardous Chemicals and Carcinogens, 5 th
edition, two volumes (Pohanish, 2008)
(References substances for the 1st responder or industrial hygienist)
17. Clinical Toxicology, 1st edition (Ford et al., 2001)
(Symptoms and treatment of poisoning from various sources for clinicians and health
care providers)
University of the Sciences
Environmental Health & Radiation Safety Department
18. Casarett and Doull’s Toxicology: The Basic Science of Poisons, 7 th edition
(Klaassen, 2007)
(Overview of toxicology)
19. Catalog of Teratogenic Agents, 11th edition (Shepard and Lemire, 2004)
(Catalog of reproductive and developmental toxins)
20. Wiley Guide to Chemical Incompatibilities, 2nd edition (Pohanish and Greene,
2003)
(Reference listing incompatibilities of chemicals)