World Health Organization
Department of Emergency and Humanitarian Action
Technical Hazard Sheet
CHEMICAL INCIDENTS
The Hazard
1. Chemical incidents can be defined as accidental or intentional events that threaten to expose
or do expose responders and/or members of the public to a chemical hazard.
2. Incidents can be sudden and acute, when hazardous chemicals are ‘overtly’ released into the
environment. Incidents can also have an apparently slow onset, when there is a ‘silent’
release. The main scenarios are:
(i)
a detected release from a known chemical from a fixed site;
(ii)
a detected release of a known chemical from a non-fixed site;
(iii)
a detected release of an unknown chemical – typically, this will involve releases
from sites not on a hazardous site inventory, illegal/uncontrolled dumping of
chemicals, or unknown combustion products from a chemical fire; and
(iv)
a silent release, where the release was usually unrecognised.
3. Chemical incidents may manifest their presence in one of two ways:
(i)
a failure in the containment of chemicals, with or without exposure of the public;
and
(ii)
an outbreak of illness.
4. The factors leading up to an incident include poor maintenance of manufacturing and storage
equipment, lack of regulation and/or poor enforcement of safety regulations, road traffic
accidents, human error, natural events such as heavy rain, earthquakes, hurricanes, floods,
and terrorism.
5. Chemical incidents range from small releases to full-scale major emergencies.
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Factors of Vulnerability
6. Most incidents occur at the interfaces between transport, storage, processing, use, and
disposal of hazardous chemicals, where these systems are more vulnerable to failure, error or
manipulation.
7. Exposure levels will in general be quite different for different people involved in a chemical
incident:
(i)
employees and other on-site persons -- usually more than one exposure pathway,
often inhalation of vapour and skin contact from splashing and clean-up;
(ii)
emergency services – usually close to the emergency and involved in rescue,
containment of chemicals, putting out fires; primary and secondary contamination
of fire officers, ambulance officers, other emergency staff; secondary contamination
of medical staff and other hospital patients of incomplete decontamination of
causalities;
(iii)
public – exposure via air, water, food, soil etc.
8. Factors that affect the vulnerability of responders and the public include the nature of the
hazard, the level of exposure, availability and quality of shelter, availability of Personal
Protection Equipment (PPE), access into and out of the site, the degree to which employees
and responders (and possibly the public) are prepared and trained to deal with an chemical
release and the amount of training provided. Vulnerability can be reduced by ensuring that
information is available on:
(i)
the incident;
(ii)
measures being taken to contain the release;
(iii)
who is currently under threat;
(iv)
what the health effects might be from exposure;
(v)
(vi)
what the public can actually do to protect themselves; and
how to get further information; when, where and how it will be available.
9. Some individuals and sub-populations can also be at increased risk because they are more
susceptible to the adverse effects of a given exposure. Among the potential causes of
enhanced susceptibility are inherent genetic variability, age, gender, pre-existing disease (e.g.
diabetes, asthma), inadequate diet, occupational, environmental or lifestyle factors (e.g.
smoking), stress and inadequate access to health care.
10. Common measure to reduce vulnerability and health risks of chemical incidents are:
-
locating chemical sites away from centres of population;
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-
-
registration of all chemicals in commercial establishments with a hazard inventory
to ensure rapid identification of the released chemical;
regular evaluation of plans and their implementation;
inspection/monitoring and enforcement of safety measures;
reducing the amounts of chemicals stored;
appropriate labelling of all chemicals;
rapid notification of the chemical incident emergency services in the event of a
chemical release;
regular surveillance and standardized reporting of incidents, including the small
“routine” ones;
measures to decontaminate land or water already contaminated by waste disposal;
measures to prevent or contain fire-fighting water run-off;
construction of drainage ditches or holding tanks to contain liquid chemicals.
Main causes of Mortality and Morbidity
11. In most cases the mechanisms and health outcomes of exposure are unknown. Symptoms
may present themselves differently depending upon the chemical involved. In general, the
adverse health outcomes to toxic chemical exposure may be:
(i)
effects that are local or arise at the site of contact with the chemical, such as
bronchoconstriction from respiratory irritants, or irritation of the skin and eyes by
gases, liquids and solids;
effects that are systemic or affect organ systems remote from the site of absorption,
such as depression of the central nervous system from inhalation of solvents, or
necrosis of the liver from the inhalation of carbon tetrachloride; and
(ii)
effects on mental health arising from real or perceived releases, which depend on
the psychosocial stress associated with an incident.
12. The time elapsing between exposure and the onset of symptoms can vary:
(i)
Some effects, for example eye and respiratory irritation or central nervous system
depression, can occur rapidly, within minutes or hours of exposure (acute effects).
(ii)
Other effects, for example congenital malformations or cancers, may take months or
years to appear (delayed effects).
13. The duration of the symptoms can also vary, from short term, to long term or chronic.
14. Chemical incidents (especially acts of terrorism) may also cause fear and anxiety in
populations.
Foreseeable Needs
15. In any chemical incident, there are a number of essential steps to go through as part of the
chemical incident plan. These are in an approximate chronological order:
-
alerting the health care services;
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-
best outcome assessment of actions and management options;
public information and public warnings;
advice on protection;
sheltering or evacuation;
other restrictions to protect public health;
organizing registers and samples;
collections of (human) samples;
environmental monitoring.
Don’t Forget
Preparedness:
16. That careful planning and thorough preparedness are prerequisites for an effective response
to chemical incidents.
17. That public authorities, at all levels, and the management staff of installations where
hazardous chemicals are produced, stored etc. should establish emergency preparedness
plans.
18. That all responsible parties should ensure that manpower equipment, and financial and other
resources necessary to carry out emergency plans are readily available for immediate
activation in the event, or imminent threat of an accident.
19. That all personnel involved in the emergency response process should be adequately
educated and trained.
Response:
20. That depending on the level of potential exposure, risk zones are usually established around
an incident:
(i)
The hot zone, is the area where first responders must use protective equipment to
prevent primary contamination;
(ii)
The warm zone, which surrounds the hot zone, is the area where appropriate
personal protective equipment must be worn to prevent secondary contamination;
(iii)
The decontamination line separates the warm from the cold zone; and
21. That a vulnerable zone (in effect a potential hot zone) can be declared, which is the area
likely to be contaminated if the emergency response action are not successful. The population
within the vulnerable zone includes the resident population as well as the working population
(in the plant and in the area), and other populations in the area at certain times, such as
motorist, tourists and visitors to entertainment facilities.
22. To set-up a public health team which, in case of an chemical incident, will provide accident
and emergency departments with information about the nature of the chemicals(s), any
precautions to be taken, and information about secondary contamination and how to
decontaminate causalities, staff and equipment.
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23. To contact the nearest Poisons Centre in case advice on diagnoses and treatment of chemical
poisonings is needed. A list of global Poison Centres is available from the WHO INTOX
Progarm http://www.intox.org/firstpage.htm. WHO INTOX can also be contacted at
ipcsintox@who.int.
24. To be aware of the OECD/UNEP International Directory of Emergency Response Centres of
Chemical Incidents (available at http://www.oecd.org). The directory provides a means for
obtaining
(i)
information needed in preparing, or responding to , chemical incidents;
(ii)
advice in establishing emergency response centres or programmes; and
(iii)
technical assistance in dealing with a response to a particular incident.
25. The importance of communication in a crisis situation to avoid unnecessary panic and fear.
Inappropriate Response
26. Ignorance and poor preparedness e.g. in not understanding the importance of adequate
decontamination so that ‘dirty’ victims are allowed into clean zones, thereby increasing the
number of people exposed to the chemical.
27. Panicking, and evacuating the public when it would be better to advise them to stay indoors
and close all windows etc.
28. Ignorance and poor investigation of potential delayed and long-term effects and to assume
that once the acute incident phase is over and the acute health effects are dealt with there are
no additional potential health problems in exposed populations.
Prepared by:
International Programme on Chemical Safety (IPCS) for the Department of Emergency and
Humanitarian Action/Emergency Health Intelligence and Capacity Building, World Health
Organization, Geneva, Switzerland
Please contact: eha@who.int for further information.
Contacts for specific related topics
For further information on:
Please contact
Chemical incidents
Dr K. Gutschmidt
+41 22 791 3731 or GutschmidtK@who.int
For information on chemicals; diagnosis and treatment:
The International Programme on Chemical Safety IPCS INCHEM database is available on the
web free of charge at http://www.inchem.org/ IPCS INCHEM is a means of rapid access to
internationally peer reviewed information on chemicals commonly used throughout the world,
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which may also occur as contaminants in the environment and food. It consolidates information
from a number of intergovernmental organizations whose goal it is to assist in the sound
management of chemicals. IPCS INCHEM includes the following collections of publications:
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IPCS Environmental Health Criteria monographs
IPCS Concise International Chemical Assessment Documents
IPCS Health and Safety Guides
IPCS International Chemical Safety Cards
WHO/FAO Pesticide Data Sheets
JECFA monographs
JMPR evaluations
IPCS Poisons Information Monographs
IPCS/EC Evaluation of Antidotes Series
ILO/CIS Chemical Database
UNEP-processes OECD Screening Information Data Sets
The IPCS INTOX database is available on the web free of charge at
http://www.intox.org/databank/index.htm. This database is an essential source of toxicological
information. It includes the following internationally peer-reviewed documents:
-
Poisons Information Monographs
Treatment Guides
Antidote Monographs
Environmental Health Criteria Monographs
International Chemical Safety Cards
WHO/FAO Pesticide Data Sheets
a worldwide list of poison centres
others.
For further reading:
Assessing the health consequences of major chemical incidents – epidemiological
approaches. WHO Regional Publications, European Series, No 79, Copenhagen, Denmark,
1997.
Awareness and Preparedness for Emergencies at Local Level (APELL): A process for responding
to technological accidents, UNEP/IEO, Geneva, 1998.
Guiding Principles for Chemical Accident Prevention, Preparedness and Response:
Guidance for Public Authorities, Industry, Labour and Others, Environmental Monograph No
51 (currently under revision) , Organisation for Economic Co-operation and Development
(OECD), Paris, 1992 (available at http://www.oecd.org).
Health Aspects of Chemical Accidents. Guidance on Chemical Accident Awareness,
Preparedness and Response for Health Professional and Emergency Responders.
Environmental health Monograph No 81, UNEP, IPCS, OECD, Paris, 1994.
International Directory of Emergency Response Centres of Chemical Accidents. A joint
publication of United Nation Environment Programme (UNEP) and , Organisation for
Economic Co-operation and Development (OECD), Paris, 2002 (available at available at
http://www.oecd.org).
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IPCS Guidance for National and Regional Policy Makers in the Public/Environmental Health
Roles, WHO Collaborating Centre for Chemical Incidents, University of Wales Institute Cardiff
(Copies are available from, healthchem@uwic.ac.uk; and GutschmidtK@who.int)
Noji, Eric. The Public health Consequences of Disasters, Oxford: OUP, 1997.
Rapid health assessment protocols for emergencies (Chapter 9 on Chemical Emergencies).
WHO, Geneva, 1999.
WHO Guidance on the Public Health Response to Biological and Chemical Weapons, WHO,
Geneva, 2001 (available at http://www.who.int/emc/book_2nd_edition.htm)
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