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    International Clearing House for Major Chemical Incidents

    A WHO Collaborating Centre

    Public Health and Chemical Incidents

    Guidance for National and Regional Policy Makers in the
    Public/Environmental Health Roles


    The International Programme on Chemical Safety (IPCS), established
    in 1980, is a joint venture of the United Nations Environment
    Programme (UNEP), the International Labour Organisation (ILO), and the
    World Health Organization (WHO). The overall objectives of the IPCS
    are to establish the scientific basis for assessing risk to human
    health and the environment from exposure to chemicals, through
    international peer-review processes, as a prerequisite for the
    promotion of chemical safety, and to provide technical assistance in
    strengthening national capacities for the sound management of

    The Inter-Organization Programme for the Sound Management of
    Chemicals (IOMC), was established in 1995 by UNEP, ILO, the Food and
    Agriculture Organization of the United Nations, WHO, the United
    Nations Industrial Development Organization, and the Organisation for
    Economic Co-operation and Development (Participating Organizations),
    following recommendations made by the 1992 United Nations Conference
    on Environment and Development to strengthen cooperation and increase
    co-ordination in the field of chemical safety. The purpose of the IOMC
    is to promote co-ordination of the policies and activities pursued by
    the Participating Organizations, jointly or separately, to achieve the
    sound management of chemicals in relation to human health and the

    WHO Collaborating Centre for an International Clearing House for
    Major Chemical incidents
     Director: Professor Gary Coleman, University of Wales Institute,
    Cardiff, UK
     Associate Directors: Professor Stephen Palmer, University of Wales
    College of Medicine, Cardiff, UK
    Professor Phillip Routledge, University of Wales College of Medicine,
    Cardiff, UK

    First published in 1999 by WHO Collaborating Centre for an
    international Clearing House for Major Chemical Incidents.

    (c) 1999 WHO Collaborating Centre for an International Clearing House
    for Major Chemical Incidents.

    ISBN 1-902724-10-0

    Photocopying: You may freely reproduce parts (only) of this
    document. However, we do ask that you acknowledge the source.

    Further copies are available from: WHO Collaborating Centre for an
    International Clearing House for Major Chemical Incidents, University
    of Wales Institute, Cardiff, Western Avenue, Cardiff, CF5 2YB, UK.

    Tel: +44 02920 416852

    Fax: +44 02920 416803







    The public health problems of acute chemical incidents

    The problems caused by the lack of public health involvement

    Roles at the national level

    Recommended actions at Government level

    Roles at the local level

    Recommended actions at the local level


    Background information

    Planning and preparedness

    Routine activities

    Helping to deal with incidents

    Assessing the impact on the health of the public

    Remediation, restitution and rehabilitation

    Guidelines and legislation required


    International functions

    National functions

    Local functions


    A - Editorial Panel

    B - Groups contributing to the policy document

    C - Individuals contributing to the working groups

    D - Conclusions from the IPCS working groups

    E - Examples of major chemical incidents

    F - Diagram of incident site risk zones

    G - Diagram of pathways of exposure

    H - Data sources

    I - List of acronyms and contact addresses

    J - Glossary

    K - Bibliography and references


    Chemical exposure has always been a feature of human society. Before
    human beings started making new chemical substances, they were exposed
    to poisonous plants, venomous animals, and chemicals of natural
    origin, such as produced by fire. With the onset of mining and
    smelting of minerals, workers were exposed to fumes and dusts.
    Poisoning occurred in early civilizations through the use of lead and
    mercury. However, the rapid industrialization of the last century, the
    increasing numbers and volume of chemicals produced in this century,
    and the growing global market in chemicals of the recent decades has
    accelerated dramatically the range of chemicals and types of exposure
    experienced by individuals and populations.

    The public has become aware and increasingly concerned about exposure
    to chemicals, particularly through major chemical incidents, such as
    the Minimata mercury poisoning, the Itai-Itai disease caused by
    cadmium, the Seveso and Bhopal incidents involving dioxin and methyl
    isocyanate, respectively, and the Spanish toxic oil episode. Incidents
    such as these cause fear, and sometimes panic, in populations. They
    are frightening because they have the potential to cause large numbers
    of deaths and disabilities and because they raise questions about the
    fragility of technologies over which society, and the local community
    in particular, may lose control. Expressions of concern have also been
    increasing, not only by the public, but also by the scientific and
    medical community, that there may be long-term effects on human
    health, such as the development of cancers and congenital
    malformations, resulting from these chemical incidents. Furthermore,
    there is concern that exposure to chemicals may be giving rise to
    diseases, not hitherto recognized, or exacerbating diseases of another

    Governmental authorities in many countries now recognize that these
    concerns need to be faced, both to allay unnecessary fears and to take
    timely, cost-effective action, where appropriate, to protect human
    health and the environment, and to mitigate deleterious effects of
    chemical incidents.

    The International Programme on Chemical Safety (IPCS) was established
    in 1980 by the World Health Organization (WHO), the International
    Labour Organisation (ILO) and the United Nations Environment Programme
    (UNEP) to provide, through chemical risk assessment, an
    internationally-evaluated, scientific basis on which countries may
    develop their own chemical safety measures, and to strengthen national
    capabilities for prevention and treatment of harmful effects of
    chemicals and for managing the health aspects of chemical emergencies.
    Through an informal IPCS Consultation of Experts, held in February
    1992, a number of scenarios of concern to governments were identified
    where guidance was needed if health and environmental authorities were
    to meet their responsibilities for protection of human health and

    the environment. These scenarios included: chemical incidents 
    involving human exposure with or without immediate health effects; 
    where exposed persons needed to be followed-up for possible sequelae 
    or delayed effects; and observation of health effects of unknown 
    cause, but suspected chemical aetiology. As a result of this 
    consultation, and in pursuance of its mandate in the field of
    chemical safety, the IPCS decided to prepare guidelines
    for governments as to the roles of health and environmental
    authorities in meeting their responsibilities in relation to these
    scenarios. Further, to support the work of the WHO in the area of
    chemical incidents, two WHO Collaborating Centres were established,
    one on the "Health Aspects of Chemical Accidents" at the Utrecht
    University Hospital, in the Netherlands, the other for an
    "International Clearing House for Major Chemical Incidents", at the
    University of Wales Institute, Cardiff, in the United Kingdom.

    The United Nations Conference on Environment and Development (UNCED),
    held in Rio de Janeiro, Brazil, in June 1992, defined an international
    strategy for environmentally sound management of toxic chemicals
    within the principles of sustainable development and the improvement
    of quality of life for humankind. Promotion of effective international
    cooperation with respect to prevention of, preparedness for and
    response to emergencies and incidents involving chemicals, including
    management of poisoned patients, follow-up of sequelae, and incident
    site clean-up and rehabilitation, is one of the important aspects of
    sound management of chemicals identified by UNCED. Following UNCED,
    the IPCS has played a central role in establishing strengthened
    cooperation among international organisations through the
    Inter-Organization on Sound Management of Chemicals (IOMC), and in
    setting up an Intergovernmental Forum on Chemical Safety (IFCS). In
    relation to chemical incidents, the IPCS is dealing mainly with the
    health and medical aspects.

    A number of important international initiatives have already been
    undertaken in relation to the health aspects of chemical incidents. In
    1989, "Methods for Assessing and Reducing Injury from Chemical
    Accidents" was published jointly by the IPCS and the Scientific
    Committee on the Problems of the Environment (SCOPE) of the
    International Council of Scientific Unions (ICSU). In 1994, the IPCS,
    the Organisation for Economic Co-operation and Development (OECD), the
    United Nations Environment Programme Industry and Environment
    Programme Activity Centre (UNEP-IE/PAC) and the WHO European Centre
    for Environment and Health (WHO-ECEH) published "Health Aspects of
    Chemical Accidents", giving guidance on chemical incident awareness,
    preparedness and response for health professionals and emergency
    responders. In 1996, OECD issued guidance concerning the "Health
    Aspects of Chemical Accidents", as a supplement to its "Guiding

    Principals for Chemical Accident Prevention, Preparedness and
    Response". In 1988, UNEP produced its APELL Handbook ("Awareness 
    and Preparedness for Emergencies at Local Level") which gives 
    a ten-step process of instituting or planning for, preparation 
    of, and response to incidents at local level through cooperation
    between industry, local authorities and the public.

    Following the consultation in 1992, the IPCS organised two
    international conferences (Cardiff, UK, 1-3 April 1993, and Sao Paulo,
    Brazil, 6-11 June 1994), at which a number of well-known chemical
    incidents were examined with a view to identifying the lessons to be
    learned by the health sector in dealing with such incidents. In
    consultation with an editorial panel (see Appendix A), guidance
    material on the public health sector role in chemical incident
    preparedness, response and follow-up was then drafted, based on the
    conclusions and recommendations of the two conferences. This draft
    material was examined at a number of IPCS workshops held in Wales, UK
    between 1995 and 1998 (see Appendices B and C) and subsequently
    assembled into a guideline document, which enabled the general
    principles for this policy document to be identified.

    The IPCS gratefully acknowledges the financial support of the UK
    Department of Health, through its annual contributions to the
    Programme, throughout the period during which this activity was being
    undertaken. The lead role of the WHO Collaborating Centre for an
    International Clearing House for Major Chemical Incidents, UWIC, in
    the preparation of this document is also greatly appreciated.

    John Haines


    Structure of this document

    This document describes how countries can improve the public health
    response to acute chemical incidents, and ensure a better outcome for
    the health of their populations.

    Part 1 is a succinct summary for the policy maker at government and
    regional level, and describes the major public health problems posed
    by chemical incidents and the actions that need to be taken by policy

    Part 2 gives more details of the public health response to an
    incident. It has two purposes. Firstly, it is provided to give the
    interested policy maker greater insight into the technicalities of the
    public health approach. More importantly, though, this section is
    offered as a template for all the public health functions that will
    need to be introduced into every country to ensure an adequate public
    health response.

    Part 3 takes the functions as described in Part 2 and offers a
    suggested model, or structural framework, into which these functions
    can be built. It is intended purely as a model. There will be many
    possible ways of ensuring the provision of a comprehensive public
    health response - from wholly self-contained to wholly contracted in.
    There are some international structures already in place and these are

    Part 4 contains the appendices, covering for example individuals
    contributing to the document, examples of major chemical incidents,
    and a bibliography and the references.

    Guidance for public health policy makers


                      emergency services deal with acute
                             chemical incidents

    This policy document has been written primarily to give
    policy makers at national and regional level a broad understanding
    of the problems posed to the health of people and populations, as well
    as the environment, when a chemical incident occurs and chemicals are
    released into the environment. Often, the release will have occurred
    at a specific site - the incident scene. For this sort of release,
    the emergency services become involved and, by and large throughout
    the world, are well prepared, trained, and organised to cope with the
    release itself. They put out any fires, try to contain any liquid
    chemicals and rescue casualties. The chemicals, however, are often
    dispersed, into the air, onto the soil, or into the water etc.

    In other sorts of incidents, the chemical is released into food or
    water. Occasionally, the release is silent and is only announced by an
    increase in symptoms or illness. In these cases, there is no scene,
    the emergency services are not involved, and it is other services,
    such as water authorities that become involved.

                     the impact on the public's health is
                           usually not considered

    What is rarely addressed, though, is the impact that the release of
    the chemical (and any containment or clean-up processes) has on the
    health- both the short term and the long term - of individuals
    and the public, and what difference there might have been to the
    health of the people if different courses of action had been taken by
    the emergency responders.

             public health professionals are trained to do this

    Addressing the impact on populations and advising on the best course
    of action to minimise the health impact is the role of the public
    health services. Public health is also concerned with the study of
    the distribution and determinants of diseases in populations. Public
    health / environmental health professionals are trained in
    epidemiological techniques and in the application of management skills
    to achieve change. These techniques and skills have typically been
    applied to the control of infectious diseases and food poisoning
    outbreaks. To be able to apply these techniques and skills to acute
    chemical incidents, some additional training will often be required.
    However, once this knowledge and expertise has been gained, it should
    be possible for public health / environmental health professionals, as
    full members of the emergency response team, to advise on the best
    course of action for the emergency responders to take.

    The public health response in an acute chemical incident is

    *     the assessment of the likely impact on the health of the
          first responders exposed people and the population

    *     the provision of evidence-based advice on appropriate
          measures to be taken to minimise the loss of health, both
          mortality and morbidity, and

    *     the follow-up of exposed people.

                  public health capability needs developing

    Generally throughout the world, this public health response is poorly
    developed. Often, it will require considerable development to
    provide sufficient public health / environmental health professionals
    with the proper training and experience at the national and regional
    level. This development can often usefully be conducted in parallel
    with the development of other public health functions, such as
    infectious disease control or food poisoning outbreak control. Once
    developed, a strong and vital public health response can only be
    achieved if public health/environmental health professionals are full
    members of the planning teams and emergency response teams.

    The Public Health Problems of Chemical Incidents

                      unpredictable nature of incidents

    Chemical incidents can happen any where, and at any time. This is true
    even if there are no chemical installations in the area. Lorries can
    spill their contents, rail tankers can overturn, and clouds of
    chemical vapour can drift over in the wind or be deposited in the
    rain. The vast majority of chemical incidents are not the
    media-grabbing type, such as Bhopal (see page 12). They are smaller,
    and involve less people; but they are none-the-less just as serious in
    terms of illness, death and anxiety to people, the public, the
    emergency services and employees.

                 problems if public health professionals are
                          not involved in planning

    Experience has shown that preparedness is the crucial factor for the
    successful management of chemical incidents. The most important areas
    for preparedness are incident combat (plugging the leak, extinguishing
    the fire etc), medical treatment, clean-up, and, most importantly from
    the point of view of the affected public and the emergency services,
    dealing with the questions and uncertainties about the health effects.
    Sadly, the sector with the expertise and knowledge to deal with this
    aspect public health / environmental health specialists - is often

    left out of the planning and management of chemical incidents. Below
    are a couple of examples of chemical incidents that had a public
    health outcome, including one where public health involvement was
    lacking and where a different outcome might have been achieved if it
    had been present.

    Water-based contamination - Camelford UK

    On 6th July 1988, a relief driver mistakenly emptied 20 tonnes of
    aluminium sulfate solution from his tanker into the contact chlorine
    reservoir of a small, unmanned drinking water treatment plant in the
    UK. Because there had been a technical problem at the site a few hours
    earlier, the resulting increase in levels of aluminium were not
    recognised until several days later. Aluminium levels of 620,000mg/l,
    sulfate levels of 4,500,000mg/l and pH values of 3.9 - 5.0 were
    recorded. Some 12,000 local residents and a further 8,000 holiday
    makers were put at risk.

                 aluminium sulfate emptied into water supply

    Once a problem had been identified, the water authority installed
    bowsers, but did not reveal publicly the cause of the incident.
    Neither was an immediate rapid epidemiological assessment carried out.
    An inquiry was ordered in mid July, which reported in August, by which
    time much public anxiety and media interest about the long-term health
    consequences had been raised.

             Considerable public anxiety could have been avoided

    Two further public inquiries and several epidemiological studies were
    initiated over the next two years, which found an increased incidence
    in a wide range of symptoms in the people who were exposed. However,
    the researchers were unable to exclude the possibility that the
    associations could have been due to anxiety and the publicity
    associated with the incident.

    Considerable public anxiety and unrest continued for a number of

    Air-borne contamination from a fixed site - Bhopal, India

               poor land-use planning led to many people dying

    Union Carbide Corporation had a number of tanks storing methyl
    isocyanate (MIC) within its plant at Bhopal. On the night of 2nd/3rd
    December 1984, tank 610, containing 42 tonnes of MIC, started leaking
    following a rise in pressure. The gaseous cloud caused immediate lung
    and eye problems, and killed, ultimately, 2800 people, injured and
    debilitated between 50,000 and 150,000 people, hospitalised

    immediately 1400 people and caused widespread panic in the 5 million
    local residents. A second, neighbouring tank 611 threatened to leak,
    causing many people to leave the area until it was made safe. It is
    the worst chemical disaster in the world to date.

    Considerable controversy surrounds the question of the chemical
    composition of the chemical cloud. The tank appears to have suffered a
    considerable rise in temperature, which would likely have given rise
    to a number of byproducts. These remain unknown.

    Many clinical and epidemiological studies were started following the
    disaster, looking in particular at toxicological, immunological,
    neurological, psychological and genetic aspects. The principal long
    term effects have been on the lungs and the eyes.

    Frequency of public health chemical incidents

    Public health chemical incidents are surprisingly common. There are a
    number of databases in the world that have collected comprehensive
    public health surveillance data about chemical incidents in their
    countries. The Agency for Toxic Substances and Disease Register
    (ATSDR), in the USA, has the largest current one - the Hazardous
    Substances Emergency Events Surveillance System (HSEES). The National
    Focus for Work on Response to Chemical Incidents (National Focus), in
    the UK, started a national surveillance system in 1998. A pilot
    surveillance system collected data from Wales during 1993 to 1995 
    - the All-Wales Environmental Health Surveillance Project (AWEHSP). 
    Data from the HSEES and the AWEHSP are produced in Table 1.

        Table 1

    frequency and outcome of all public health chemical incidents
    in the USA and Wales: UK

    Database  Period    Area / pop   Number          Died   Affected   Evacuated
                        covered      of incidents

    HSEES     1993-7    Part of USA  24,573          111       9652    23,851
                        80m. pop

    AWEHSP    1993-5    Wales        330             5         473     0
                        3m. pop
             chemical incidents involving the public are common

    There is no international database that collects data on public health
    chemical incidents down to the level of these national databases.
    However, the United Nations Environment Programme (UNEP) does produce
    a list of all the large incidents that have involved a hazardous
    substance -large being where 25 or more people have been killed, or
    125 or more people have been injured or 10,000 or more people have
    been evacuated.

    In the 28 years between 1970 and 1998, the data were as follows:

        Table 2
    Frequency and outcome of large scale public health chemical
    incidents, 1970 - 1998


    Geographical area   Number of large    Died     Affected   Evacuated
                        scale incidents

    USA                 87                 372      14,356     517,000

    UK                  9                  167      489        133,000

    Worldwide           350                13,000   100,000    3 million
                     incidents that threaten the public

    It can be seen that, in the USA and UK, the ratio of the annual number
    of large scale incidents to all incidents (about 1:1600 and 1:400
    respectively) is low. Thus, if the same ratios were applied to the
    worldwide number of large scale incidents, the estimated number of all
    incidents could range from 100,000 to 500,000 per year. (These figures
    are broadly indicative only, and must be taken with caution) A list of
    these large scale incidents is provided in Appendix E.

    What is a public health chemical incident?

    Many chemical incidents occur which do not threaten the safety of the
    public. This document is concerned with those incidents that do - that
    is, incidents that threaten to expose, or actually expose, two or more
    members of the public (ie: people who are not employees or first
    respondents) to a chemical hazard. These incidents are usually sudden
    and acute, although they tan include chronic incidents where the
    public has just become aware of the release and the potential threat
    to health. Deciding that an incident is a threat to the public health,

    and who should make that decision, may not always be easy matters to
    determine. Chemical incidents may be accidental or intentional (ie
    malicious or caused by terrorists).

    Outcomes of chemical incidents

                      public concern is rising rapidly

    Analysis and experience of these has shown that the range of outcomes
    from incidents that affect the public health are:


                           Public Health Outcomes
                            of Chemical Incidents


                               Public anxiety


                             Deaths and illness


                           Delayed health effects


                           Damage to local economy


                              Opportunity costs


                                 Legal costs


                            Rehabilitation costs


     Public anxiety The public's perception of the risk to their health
    from chemical incidents has changed dramatically over the last twenty
    years. Communities, pressure groups and the media are becoming
    increasingly interested in chemical incidents. Governments are coming

    under rising pressure to demonstrate that there are policies,
    personnel and other resources in place to effectively deal with
    incidents, that the management of any incident will be in competent
    hands, and that the harm to the public is minimised.

    During an incident, this public anxiety leads to pressure on
    politicians and policy makers, as well as health professionals, to
    provide information about the short, medium and long term risks to the
    health of the people exposed. Because of the lack of public health
    involvement in the assessment of the health effects of chemical
    incidents, these questions are often difficult to answer. This has led
    in many countries to a loss of confidence by the public in the ability
    of national and local government, and particularly the public health
    services, to protect them.

                  large number of people have been affected

     Deaths and illness Large incidents, with extensive media coverage,
    are thankfully rare, but in all, the reported incidents, both large
    and small have caused in the order of 13,000 dead, 100,000 injured or
    ill and nearly 3 million people to be evacuated over the last 28 years
    worldwide (see Table 2). Evidence from ATSDR (the Agency for Toxic
    Substances and Disease Registry, USA (Jones  et al 1993)) and from a
    survey in Wales, UK (The All-Wales Environmental Health Surveillance
    Project 1993 - 1995 (Bowen 1999)) has also shown that there are very
    many small chemical incidents that are unreported but which put the
    public at risk, raise considerable anxiety and often cause fatalities
    or injuries requiring hospital admission.

     Delayed health effects Chemicals do not necessarily produce an
    immediate effect. Depending on the level of chemicals taken into the
    body (the dose), there may be long term chronic effects, or effects
    that appear only years later. Examples of long term effects are skin
    scarring and disfigurement from burns, respiratory difficulties from
    damage to the lining of the lungs, and so on. Delayed effects occur
    mainly as cancers, or teratogenic effects - problems appearing in the
    offspring during fetal development.

     Economy The local and national economy can be affected. Livelihoods
    and productivity can be interrupted, often for long periods of time.
    Community anxiety can be raised, affecting inward investment.

                   environmental impacts are considerable

     Opportunity costs Whenever a chemical incident occurs, opportunity
    costs are encountered. Examples of these are the closure of
    contaminated health facilities, the costs of monitoring the
    pollution, and the costs of decontaminating the waterways, soil or
    food stuffs.

     Litigation and compensation When people have been injured or their
    livelihoods interrupted, they frequently look for compensation. The
    time taken to apportion blame and the legal processes all add
    considerably to the final costs of any incident.

     Costs of rehabilitation The environment may have been extensively
    damaged by the incident, or may require extensive remediation to
    return it back to its previous state. Frequently, the clean-up
    operation of large spills requires large amounts of top soil or beach
    sand to be removed and disposed of safely. The costs of
    decontamination and the resulting effects on the environment and
    wildlife can be considerable.

     The polluter rarely pays The evidence from around the world is that
    the polluter rarely pays. Often the polluter is unidentified, and
    considerable resources have to be expended to identify the chemical
    and the source. Even when the polluter has been identified and is
    clearly at fault, the legal process of bringing an action can take
    many years. It is usual, therefore, for national or local governments
    to pay for the majority of the costs of chemical incidents that affect
    the public and public areas.

    The problems caused by lack of involvement by public
    health professionals

                   the population effect is not considered

    The problem with many incidents is that there is no person or
    organisation present to take an objective, detached and holistic
    public health view of the incident. Each government agency is
    committed to fulfilling its own objectives and functions. There is
    often no person or organisation with the time or expertise to consider
    the impact of an action or decision on the health and well-being of
    the local population. This means that the best courses of action are
    not considered or researched, people are not registered to be followed
    up, and the long term health effects are not investigated.

    Public health personnel are specifically trained to take this view, to
    consider the long-term effects, and to balance the different overall
    effects on the public. They are trained in appropriate research
    methods, in epidemiological approaches and in methods of multi-agency
    working and public relations.

    The roles at government level

    The roles for government are:

                 ensure high quality public health services

    1. At the LOCAL level, to ensure that the public health management of
    chemical incidents is comprehensively, effectively and efficiently
    conducted, so as to achieve the best outcome in terms of the health of
    the public whenever a chemical incident occurs. Additional national
    specialist support may be necessary for this.

                        assume overall responsibility

    2. At the NATIONAL level, to take responsibility and to be accountable
    to the public for their protection and the overall management of
    public health chemical incidents.

    Recommended actions at government level

    To ensure that these roles are met, government will need to carry out
    the following actions:


                             Recommended Actions



                       Identify responsible individual


                         Establish inter-departmental


                            Draw up national plan


                              Review legislation


                               Set up national
                             surveillance systems


                         Ensure sufficient specialist
                            health care facilities


                       Ensure sufficient resources for
                         epidemiological surveillance
                               and assessments


    1.  Identify a responsible government individual or department An
    individual or department needs to be identified who will be
    responsible for ensuring that the national public health plan for
    dealing with chemical incidents is implemented.

    2.  Establish interdepartmental collaboration There will be a number
    of separate departments within government each of which may have
    statutory responsibilities for areas covering chemical incidents. The
    public health response at a government level to a chemical incident is
    to balance the requirements and actions of the various departments to
    achieve the best public health outcome. This requires coordination and
    collaboration across the departments in advance of, and most
    particularly during any incident.

    3.  Develop a national plan for dealing with chemical incidents A
    national plan needs to be developed, which makes explicit the
    policies of the government, identifies the gaps in the service and
    any needed, sets targets and minimum standards at the national and
    local level, enacts the necessary legislation and enables a
    political and administrative response in the event of a significant

    4.  Improve the legislative context Legislation will usually be
    required for:

    *    the establishment of a hazardous sites register

    *    the control of hazardous sites

    *    building regulations

    *    land use planning

    *    the control of chemical transportation

    *    the control of waste disposal sites

    *    the control of contaminated crops, foodstuffs and drinking water

    *    formal command and control of the incident site and incident

    5.  Fulfill other national requirements The government will also need
    to establish:

    *    an efficient public relations system

    *    a national surveillance and data collection and collation

    *    a system of simulation exercises at government level

    *    an audit / evaluation system of the effectiveness and
         efficiency of local exercises and responses,

    *    that there are sufficient specialist health service facilities
         and staff nationally.

    The government should also be aware of, and plan for the fact that
    terrorist attacks are an increasing possibility. These attacks may
    use chemicals or biological agents, or may target chemical sites.

    6.  Establish a comprehensive national public health function and
     structure. Chemical incident management is only one of a number of
    functions that can be performed by public health staff. These can
    include the control and management of outbreaks of infectious
    diseases, food poisoning, various aspects of major emergencies and
    disasters, the collection and interpretation of population health
    status data and various methods of controlling the demand, supply and
    effectiveness of the health care system.

    A comprehensive public health function requires consideration of the
    recruitment, training and job market for the specialty; regulation and
    continuing professional education; the provision of epidemiological
    and other specialist skills; and the relationship with other health
    related agencies, such as housing, social services and education.

    7.  Contribute to international collaboration. Co-operation and
    collaboration at the international level are effective and efficient
    ways to ensure that:

    *    research is conducted that underpins the scientific basis of
         the public health response

    *    that lessons are learned about the public health responses to
         chemical incidents and that these lessons are promulgated to
         all countries of the world.


                             Recommended Actions



                             Establish links with
                          WHO Collaborating Centres


                   Contribute to the International Chemical
                              Incident Register


    To these ends, governments can help by contributing to the
    international development and standardisation of:

    *    guidelines for the public health management of chemical incidents

    *    chains of command: national - regional - local

    *    registration of chemical incidents

    *    data sets for the register

    *    training.

    Many of these functions are conducted by the IPCS and the
    International Clearing House, UWIC, in Cardiff, which runs the
    International Chemical Incident Register.

    The roles at the local level

    Governments will also need to ensure that, at the local level, there
    are appropriate and efficient systems to enable the following
    functions to be carried out to ensure the effective public health
    management of chemical incidents.

    1.  Advice on the best actions to achieve the best public health
     outcome of a current incident. During an incident, the principle
    public health role is to assess the overall likely impact of the
    incident on the health of the public, the first responders, the health
    care workers and the environment and to advise the first responders

    on the best actions. This assessment should take into account not only
    the chemical released during the incident, but also any consequences
    of the actions that might be taken by the emergency services to deal
    with it (the emergency response options), such as burning off,
    cleaning-up with other chemicals, flushing into the sewage system etc.
    Ideally, the assessment should consider the short, medium and long
    term health effects of the possible options. The principle role
    breaks down into the following sub-roles:


                             Recommended Actions



                   Review the public health structures and
                        links with emergency services
                             and health services


                          Ensure sufficient training


                          Ensure high quality audits


    *    Hazard identification -identifying the nature and quantity of
         the chemical and its potential effects on health as it disperses
         into the environment

    *    Risk assessment - assessing whether the release of the
         pollutant actually poses a health risk to the emergency
         personnel, employees and the public

    *    Advice to the first responders - on their own protection, and
         on matters such as personal protective equipment, casualty and
         personnel decontamination, evacuation and safe return

    *    Assessing the (likely) impact of the emergency response and any
         environmental decontamination or clean-up on the health of the

    *    Recommending the courses of action that produce the best
         public health outcome.

    2.  Advising the public the media and the politicians. Information
    and advice about the health consequences of a chemical incident are
    usually required rapidly and in an authoritative and credible way. In
    particular, public health professionals are often asked to provide
    information about the short, medium and long term health effects of
    the current contamination. They may also be called upon to be the
    focal point for the issuing of such statements, or to bear
    responsibility for health-related sections of the general
    communication with the public.

    3.  Measuring the actual health impact of the incident. Pollutants
    can have an immediate effect, a long term effect or a delayed effect.
    Public health professionals need to organise for the immediate
    measurement of the health of exposed and potentially exposed people,
    and to organise to have them followed-up as part of a proper
    epidemiological study.

    4.  Contributing to the rehabilitation of the community. Once the
    incident is over, the local community may need to rebuild the economy
    and lifestyle, and to regain its confidence in the chemical industry
    and public services. Public health professionals can contribute to
    this process.

    Recommended actions at the local level

    To ensure that these roles can be fulfilled, government will need to
    ensure that:

    1.  Competent public health services are comprehensively established
     at the local level. This maybe acheived by extending the range of
    current services (such as the control of infectious disease outbreaks)
    or by developing new services. It may require a plan and resources to
    be identified. Where services are poorly developed, the less frequent
    but more dramatic nature of chemical incidents can be a useful
    incentive to the establishment of the full range of public health

    2.  Local public health professionals have access to skills,
     expertise, and resources in the following areas:

    *    chemical and medical toxicology

    *    poisons information - on a 24 hour per day, 365 day per year,

    *    environmental toxicology

    *    environmental epidemiology

    *    environmental risk assessment

    *    environmental sampling

    *    environmental monitoring and modelling

    *    biological monitoring

    *    medical epidemiology

    *    surveillance

    *    risk assessment and hazard analysis

    *    risk perception and risk communication

    *    risk management

    *    media skills

    *    rehabilitation

    *    accident and emergency services

    *    audit

    3.  There is a comprehensive training, simulation and exercise
     function working at the local level and reporting to the national,
    central level.

    4.  Public health services are fully involved in the planning
     processes and part of the off-site command team during an incident.


    The public health environmental health functions in the management of
    an acute chemical incident

    Part 2 The chronological flow of functions

                           Background information

    This section describes the principle features of chemical incidents
    and how they affect the health of individuals, the population and
    society in general.

                          Planning and Preparedness

    These functions include the baseline / one-off / set up functions and
    activities, such as producing the chemical incident plan and community
    risk assessment.


                             Routine Activities

    These are the activities that have to be done on a regular basis, to
    ensure an efficient response during an incident. They include updating
    the plan, conducting routine surveillance, and training.


                       Helping to Deal with Incidents

    These are the functions that the public health services need to carry
    out during the acute stages of an incident.


              Assessing the Impact on the Health of the Public

    This section describes how to investigate the health effects of an


                 Remediation, restitution and rehabilitation

    This section describes how the public health services can contribute
    to the restoration of the local community once an incident is over.

                     Guidelines and Legislation Required

    The work of the emergency response team can be greatly enhanced with
    proper regulatory back-up. This section describes useful legislation.

    Background information

    Chemicals worldwide

    Chemicals have played a major role in the development of human
    societies - in agriculture and food; in industry and transport; in
    housing, and in health. Extraordinary advances in chemical technology
    have been made throughout the world in the last fifty years (United
    Nations Environment Programme 1992). Manufacturing has become far more
    complex and on a larger scale, and an ever increasing number of new
    chemicals is entering the market each year. Over 11 million chemical
    substances are known and some 60,000 to 70,000 are in regular
    use. Between 200 and 1000 chemicals are produced in excess of one
    tonne annually. Currently new chemicals are entering the market
    at the rate of about 600 each month (or over 7000 per year)
    (Lillibridge 1997).

               there is a large and ever-increasing number of
                             chemicals worldwide

    Dealing with chemicals involves manufacturing, processing,
    transportation, storage, distribution, use and waste disposal. More
    than 4 billion tonnes of hazardous chemicals are moved each year
    around the world by motorway, rail, and pipeline systems. Fertilisers,
    weedkillers and insecticides are spread in huge quantities on
    agricultural land. Thus, even if a community does not have any fixed
    chemical sites, hazards may be passing through, or being used locally,
    putting that population at risk.

    Given the increases in the production and use of chemicals, it is
    therefore not surprising that the potential for inadvertent chemical
    releases has increased, giving rise to a greater risk to human health
    and the environment.

    Types of chemical incident

    Essentially, and for the purposes of this document, a chemical
    incident is an unexpected, uncontrolled release of a chemical from
    its containment. A public health chemical incident is one where two
    or more members of the public are exposed (or threatened to be
    exposed) to a chemical.

    In the majority of cases, this is an acute release. An acute release
    is a release where the exposure dose is rising, or is likely to rise
    to rapidly.

                          chemicals are released...

    Sometimes, however, the release is chronic. This is where the
    exposure dose is not rising rapidly and public health measures do not
    have to be taken so rapidly. It may be, however, that the public
    health concern emerges suddenly and acutely. This document is
    concerned with the acute releases.

                       ... and travel through media...

    Chemicals in all their states can be involved in incidents, from
    gases - heavier or lighter than air; liquids - volatile and
    non-volatile; solids - powders, dusts, the effluent from volcanic
    eruptions; natural toxins, such as from algal blooms; and
    increasingly important these days, biological toxins and chemicals
    used in terrorist attacks. They may or may not be visible or
    odourous. What are not included in this document are releases of
    radio-active materials such as leaks from power stations, or the
    detonation of nuclear warheads.

                            ... to the human body

    The released chemical usually enters an environmental medium (the
    contaminated medium) - air, water, soil, sediment or food. In the
    air, it may form a gas or vapour cloud or plume, and may rise up and
    drift away. It may disperse completely or it may fall to earth some
    distance away, contaminating whatever it lands on. Releases into
    water may seep into the soil and then into the aquifer, into rivers
    or reservoirs and thus into drinking water. Releases onto the soil
    may be washed by rain or containment water into the aquifer or rivers,
    or be taken up by crops, grazing animals or passing people. The
    chemical may also be released onto ready-to-eat food, or onto crops.
    Sometimes the chemical releases directly onto an object - such as a
    piece of equipment, or the floor. Very occasionally, the chemical is
    released directly onto the person or animal. Indeed, it is when the
    chemical comes into contact with humans or animals, or threatens to do
    so, that the incident becomes a public health matter. The route that
    the chemical takes from its release to the human body is known as the
    pathway of exposure (see Appendix G). It enters the body through a
    portal of entry, for example, skin, lungs or digestive tract.

                     the chemicals, often unknown, cause
                         considerable public anxiety

    At the time of the release or during the control procedures, chemicals
    may react to produce thermal or aqueous degradation or reaction
    products which may themselves present greater hazards than the
    original chemicals. There is often considerable difficulty in
    identifying the chemicals or the toxic products. There is also
    limited scientific knowledge of the acute and long-term health effects
    of these products. These uncertainties can become significant
    psychological and social stressors to the exposed and the general
    public over a substantial period of time. Experience has shown that
    these stressors may then emerge as problems that are more difficult
    to manage than the original potential danger from the chemical.

    Chemical incidents can occur in fixed sites, such as chemical
    manufacturing sites, storage tanks or laboratories. They may also
    occur during transportation, on roads, rail, pipeline, waterways,
    sea or air.

                     there are many types of releases...

    The release itself may be caused by a leak or spill from a
    container, the container may break or explode1, or the chemical may
    catch fire. Chemicals may also be released naturally from volcanoes.
    The factors leading up to the incident, the contributory factors,
    include such things as poor maintenance of manufacturing and storage
    equipment, road traffic accidents, human error, poor weather
    conditions or terrorism.

                 ...affecting a few, to thousands of people

    The release itself may be detected or silent. Even if the release
    is known about, the identity of the chemical may be known or
    unknown. Different release states and identities have profound
    effects on the planning and management of incidents. Chemical
    incidents range from small releases, for example a chemical drum
    being washed ashore to full-scale major emergencies, (see Appendix H
    for examples).

    From 1993 to 1997, more than 24,000 chemical incidents were reported
    to the surveillance system in the United States (ATSDR - which covers
    14 of the 54 states of the country). Eighty-five percent involved a
    single chemical agent, most often a volatile hydrocarbon. In addition,
    evidence from the UK surveillance system showed that the majority of
    these incidents actually presented a threat to the public health
    (National Focus Annual Report - 1999).

    Toxic versus physical effects of a chemical incident

    Chemical incidents, by the very nature of the way many of them occur,
    will affect people in a number of ways.

    *    Effects of explosion. People may be subjected to blast injuries,
         mechanical trauma, the effects from building and structural
         damage and collapse, and from loss of housing and shelter.

    *    Effects of fire. People may be burnt or exposed to smoke and heat
         inhalation, or suffer from the longer term sequelae.

    *    Effects of natural disasters. People may be subjected to the
         suffocating effects of ash, to mudslides and loss of housing and

    1  a particularly dangerous example is the BLEVE (Boiling-Liquid
       Expanding-Vapour Explosion), when a sealed liquid canister is
       heated, ruptures and then explodes.

    These physical effects are often seen in major trauma incidents; and
    other emergency planning systems have usually already been developed
    to cope with these. However, it should not be forgotten that during a
    chemical incident these effects may in fact present more of a health
    problem than the chemical itself.

    *    Socio/psychological effects.

    *    Effects of the toxic nature of chemicals.

    This document is concerned with these two aspects.

    What happens at the scene of a typical chemical incident site

            there will usually be a command and control structure

    When an incident occurs, site employees and some or all of the
    emergency services usually attend the scene (the first responders).
    If formal co-ordination is required, an on-site (operational)
    command is initiated; this is usually controlled by the fire brigade.
    If the incident gets larger, or there is threat to life or property or
    public order, additional levels of command are initiated, usually
    with the police (or military) taking overall control of the management
    of the incident, at the off-site tactical or strategic command
    centre. As many services and agencies as are necessary should be
    present in the off-site command centre.

          the site is usually divided into areas of increasing risk

    Chemical incidents will present the first responders with health
    risks. These risks may be toxic (from the chemical or its
    by-products) or physical (such as explosion or building collapse).
    When the risk of contamination or physical injury is sufficient,
    protective equipment (personal protective equipment (PPE) and
    shields etc.) is used. Depending on the level of risk, risk zones are
    usually established around the incident. The hot zone, bounded by a
    hot line, is the area where first responders must use protective
    equipment to prevent primary contamination or physical injury. The
    warm zone, which surrounds the hot zone, is the area where
    appropriate personal protective equipment must be worn to prevent
    secondary contamination. The decontamination line separates the warm
    zone from the cold zone. Decontamination should be performed across
    this line. Treatment, support and command facilities are located in
    the cold zone. (see Appendix F for a diagram)

    It may also be necessary to control access to the scene of the
    incident. Public, press, sightseers and residents may try to gain
    access, putting themselves and others at risk. The first access
    control line is usually the outer boundary of the cold zone, the cold
    line. Various degrees of access may be imposed the nearer one gets to
    the incident site.

    Some other terms used to describe the various zones are:

         hot zone:   exclusion zone, red zone

         warm zone:  contamination reduction zone, yellow zone

         cold zone:  support zone, green zone.

          Primary and secondary contamination are important problems

     Casualties in the hot zone are usually collected by the fire service
    personnel and transferred across the hot line, through designated
    access control points, to ambulance personnel in the warm zone. Care
    must be taken to avoid contaminating the ambulance personnel during
    the transfer. Contaminated casualties should be decontaminated before
    removal from the warm zone, ideally in specially-designed
    decontamination units. There should be two decontamination sites, one
    for casualties, and one for first responders in protective suits.
    Casualties are often "triaged" before transfer to health care
    facilities, to identify those casualties that have the most serious
    injuries and who would benefit most from rapid transfer and treatment.

    A vulnerable zone (in effect a potential hot zone) can be declared,
    which is the area likely to be contaminated if the emergency response
    actions are not successful.

    IPCS definition

    The IPCS, following an international meeting of experts, has agreed a
    definition of an acute chemical incident requiring public health
    involvement, and four levels. These are:

    Chemical       An occurrence of public health concern caused by an
    Incident       acute release of a toxic or potentially toxic agent

    Level 1        An acute release with no human exposure

    Level 2        An acute release with suspected or actual exposure

    Level 3        An acute release where the suspected / actual release
                   is related to ill-health

    Level 4        An acute release giving rise to a civil defence or
                   equivalent major emergency.

    Effects on the health of the individual

    The effect that a chemical can have on the human body and on the
    health of the person (the morbidity), is determined by a number of
    factors. These factors are described below, starting with the actual
    release and working forward to the human body. A brief description of
    the actual effects is then given.

          a chemical can be affected by many factors on its journey
                 from the release to the tissues of the body

    Factors affecting toxic outcome

     Pathway of exposure Once a chemical has been released from its
    containment, it has to reach the body to have an effect. The route to
    the body can be varied, and will depend upon the nature of the
    release, the nature of the chemical, the types of media that are
    contaminated and their movement, and any preventive or protective
    measures that might be taken. These factors may well determine the
    portal of entry. (see Appendix G for a diagram)

     At the portal of entry The actual route into the body will affect
    the dose. Chemicals will enter the body through the skin, eyes,
    lungs or digestive tract. The rate of absorption through each of
    these barriers will be different for different chemicals. Absorption
    will also be affected by the concentration of the chemical at the
    portal of entry, which may change over time, and the exposure
    duration - the length of time that the chemical is in contact with
    the body, and air temperature, humidity and the person's age
    (particularly children).

     In the body Within the body itself, the effect will depend upon the
    actual toxicity of the chemical and the biologically effective dose
    - the quantity of chemical taken into the target tissue. The way the
    dose is accumulated in the target tissue can make a difference to its
    impact. Even if the exposure is short, the peak level might be high
    enough to cause toxic effects. Where the exposure is prolonged and the
    dose rate low, it may be the total cumulative dose that causes
    toxicity. Other factors that may have a bearing on the effect of the
    chemical are age, gender, immune state, concomitant exposures and
    general fitness of the person.

    Toxicological effects

     Presentation of the effects When a chemical has a toxic effect on
    the body, the signs and symptoms may present themselves differently.
    Every chemical has a particular pattern of injury, with adverse
    effects concentrated in certain target organs or tissues. Effects
    can be local, for example burning or blistering of the skin, eyes or
    respiratory tract. The effects can also be systemic, once the
    chemical has got into the body fluids. All organs and fluids in the
    body can be affected.

    The time elapsing between exposure and the onset of the signs and
    symptoms can vary. Some effects, for example eye and respiratory
    irritation or central nervous system depression, can occur rapidly,
    within minutes or hours of the exposure (acute effects). Other
    effects, for example congenital malformations or cancers, may take
    months or years to appear (delayed effects).

    The duration of the symptoms can also vary, from short term, to
    long term or chronic.

    Effects on the health of the public

            chemical incidents cause considerable public anxiety,

     Stress and anxiety The occurrence of major chemical incidents has
    shaped the way members of the public perceive exposure to chemical
    substances. Reports of incidents elsewhere, such as those listed in
    Appendix E, may cause fear and anxiety in populations living close to
    chemical industries. Such incidents are fear-inducing because they
    have the potential to cause large numbers of deaths and illness and
    because they raise questions about the fragilities of technologies
    over which society and the local community, let alone the individual,
    have little or no control. Concern is also increasingly being
    expressed not only by the public, but also by the scientific and
    medical community, and by pressure groups, that chemical incidents may
    lead to long-term effects on human health, such as cancers and
    congenital malformations, and that exposure to chemicals may be giving
    rise to diseases not hitherto recognised, or exacerbate diseases of
    another aetiology.

    As a result of these concerns, the public are becoming increasingly
    aware of all potential environmental hazards. With the inability of
    the chemical industry or the public health authorities to provide
    adequate information, the media are starting to quickly and loudly
    articulate those concerns. Public health authorities are increasingly
    being faced with problematic assessments of the risk to health and, in
    the absence of appropriate advice and expertise, are frequently being
    criticised for their inability to address community concerns.

    In most countries, no surveillance systems exist for gathering data on
    these incidents or for bringing their effects to the attention of
    governments and thus to policy decision makers. Only a few reports on
    the management of minor incidents have been published (the selection
    mechanism often being the amount of media exposure). These have shown
    that during a chemical incident, the emergency personnel and the
    public are commonly exposed to chemicals because they are inadequately
    trained, equipped, or informed.

                           ... morbidity and death

    During an incident, lack of information because of the wish for
    secrecy, or differing professional opinions may raise public anxiety
    levels. Occasionally, public anxiety may lead to the mimicking of

     Deaths and illness Data gathered so far around the world have
    indicated that chemical incidents exact a high price in terms of
    deaths and illness. Large incidents are thankfully rare, but they have
    caused considerable numbers of deaths. Evidence from ATSDR (Jones et
    al 1993) and from the Welsh survey (Bowen 1999) has also shown that

    there are very many small chemical incidents that will remain
    unreported unless a specifically designed and targeted reporting
    system is in place. The particular concern here is that whilst many
    people assume that there are little or no public health concerns with
    these small incidents, the evidence is very much to the contrary. The
    public is often put at risk from these events, with injuries and
    deaths occurring, and considerable anxieties raised.

    The costs to society and the economy

    There may be significant other effects of the incident upon society.
    These relate to the:

    *    Economy - livelihoods, and inward investments

    *    Opportunity costs - e.g., closures of health care facilities,
         schools, factories, etc

    *    Litigation and compensation - the costs of pursuing settlements

    *    Costs of rehabilitation - return the affected components of the
         community back to their original states.

    Planning and preparedness

                     having plans ready and rehearsed has
                    been shown to make a major difference
                      to the management and the outcome

    Careful planning and thorough preparedness are prerequisites for an
    effective response to a chemical incident. At the national level,
    government needs to set up the procedures and organisations necessary
    to ensure the effective and comprehensive public health management of
    any chemical incident. A national plan should be produced, circulated
    and discussed widely until general agreement has been reached.
    Resources will need to be found to correct deficits in the national
    provision. At the local level, public health authorities need to
    identify the potential situations where chemical incidents could
    occur, and to assess the likely health risks to exposed people,
    property and the environment if such incidents were to occur. The
    public health sector needs to be fully involved in the planning and
    preparedness process, including emergency plan development and

    Planning and preparedness at the National Level


                 Essential steps in planning and preparedness

                                National Level


                                  One person


                                 Draw up plan


                       Set up inventory of hazard sites


                   Audit and monitor training and responses


    The following steps are required to ensure a comprehensive response to
    any chemical incident:

    *    Identify a person / government department to take
         responsibility for the national co-ordination of the public
         health management of chemical incidents.

    *    Identify all the government departments, national bodies and
         experts with a responsibility and/or interest in chemical

    *    Make an assessment of the impact of previous chemical incidents
         on the health of the public and the environment.

    *    Assess the risk of, and likely public health impact of new
         chemical incidents

    *    Draw up a national plan that

         -    sets out the national structures required to ensure an
              effective local public health response

         -    lays down national policies for the public health management
              of chemical incidents

         -    ensures government inter-departmental collaboration and

         -    ensures cross-border liaison, collaboration and
              co-ordination with neighbouring countries

         -    links to international bodies such as the WHO.

    *    Establish a national major hazard site inventory and enact the
         legislation required.

    *    Conduct exercises at the national level.

    *    Allocate the resources necessary.

    *    Set up systems to monitor

         -    the production of local plans and the efficiency of local

         -    the effectiveness of the local response to actual incidents.

    Planning and preparedness at the Local Level

    There are a number of procedures and activities that need to be
    actioned and pursued by local public health / environmental health
    officials, and these are described below:

    1.   set up multi-disciplinary public health working arrangements

    2.   start networking with all interested parties

    3.   conduct a community risk assessment

    4.   conduct a baseline health assessment

    5.   if necessary, conduct a baseline environmental assessment

    6.   start liaising with the local community

    7.   draw up a public health chemical incident plan

    8.   establish access to the variety of information sources, databases
         and people with expertise

    9.   assess the comprehensiveness of the local health care facilities

    10.  pursue measures to reduce the probability of incidents

    11.  pursue measures to reduce the health effects of incidents.

    1. Set up multi-disciplinary public health working arrangements

              multidisciplinary team working (and practice) are
                 essential for good public health management

    The public health response to a chemical incident should be a
    multi-disciplinary one, as a wide range of skills and expertise is
    required (see Table 3). A multi-disciplinary team is usually the best
    way of achieving the various tasks that are necessary, both in the
    planning phase and during an incident. In addition, if the team has
    been meeting during the planning phase, then the resulting teamwork
    during an incident is likely to be greatly enhanced. A team therefore
    needs to be set up, taking into account the available staff and their
    skills and training. The team will fulfill all of the functions
    described below.

    The team, and preferably a coordinating centre, should be
    established and if possible resourced. The geographical area covered
    by the team will need to be decided upon, and will depend on the
    terrain, the population, the types and distribution of chemical
    industries, the extent of chemical risk, the availability of expertise
    and resources and the arrangement of other public health chemical
    incident teams.

    Public health services will also be required to respond to other types
    of incidents, such as infectious disease outbreaks and major disasters
    such as train crashes. Usually a team structure, with resources, is
    employed in these circumstances. Where existing structures are in
    place, it may be efficient to combine or link the several functions.
    Where these structures are not in place, the need to set up public
    health chemical incident teams can be a useful spur to the formation
    of these other structures.

    2.  Start networking

    Many people and organisations will be involved in the planning and
    management phases of chemical incidents (see Table 3). Some will be
    local, but many will be further afield, and usually only contactable
    by phone, fax or e-mail. The public health team will need knowledge of
    these people and organisations, and to have built up good
    relationships with them, so that during an incident, the maximum help
    and assistance is speedily obtained. The public health team will
    therefore need to establish a network of necessary contacts. These
    contacts will need to cover all aspects of chemical incidents, from
    planning and preparedness, through incident management and long-term
    follow-up, to audit and evaluation.

        Table 3

    People and groups in the public health chemical incident network

    other public health / environmental          central government
    health departments and institutes

                                                 major local chemical industries

    medical and environmental                    environmental groups, pressure 
    toxicologists                                groups and watchdogs

    poisons centres                              public and community groups

    toxicology laboratories                      emergency services

    clinical medical specialists                   * fire

    local hospitals                                * police

    specialist hospitals                           * ambulance

    occupational health services                   * transport

    environmental investigation                    * emergency medical responders
    and control

    environmental monitoring and                 specialist environment agencies

    biological monitoring                          * rivers

    health surveillance                            * wildlife

    medical and environmental                      * transport

    risk assessment, perception                    * ocean / sea
    and communication

                                                   * agricultural

    food safety organisations                      * air quality

    health planners                              pollution control agencies

    emergency planners                             * factories inspectorates

    local government                             weather services
    3.  Conduct a community risk assessment

    A community risk assessment is an assessment of the severity of the
    potential effects of a chemical incident in the local area. It is
    comprised of four steps:

    *    the identification of hazardous chemical sites, pipelines and
         transport routes

    *    the identification of possible incident scenarios and their
         exposure pathways

    *    the identification of vulnerable populations, facilities and
         environments, and

    *    an estimation of the health impact of potential chemical
         incidents and the requirements for health care facilities.

    It is an important early task for the public health multi-disciplinary

    The community risk assessment is conducted by the public health /
    environmental health specialists. It is a complex process, and
    involves a wide range of expertise and agencies. As much of the data
    required by each agency will overlap with others, a coordinated
    approach to data requests and collection will produce more valid and
    complete data returns. In addition, the process can be greatly
    improved by involving members of the public. They will help not only
    by providing local knowledge, but will also increase understanding and
    allay anxiety by relaying the methods and findings back to the
    community. Conducting a community risk assessment develops and
    strengthens the relationships between the emergency services, the
    chemical industry, the general public and the public health services.
    It will also help to identify training requirements.

                           identify high risk sites

     Hazardous Sites Assessments The identification of hazardous sites in
    the local community is an important means of recognising possible
    emergency situations. Once identified, it may be possible to check the
    availability of appropriate expertise, site emergency plans,
    materials, decontamination equipment, antidotes, and site evacuation
    procedures. There are however, no generally accepted guidelines for
    doing this, and it will be best to pool ideas and experience from all
    members of the team.

    Ideally a local inventory should be collated. However, this will need
    to be kept up-to-date, and mechanisms need to be introduced to enable
    reporting of changes and to administer the register. Chemicals may
    change quite frequently, for example seasonal chemicals such as
    fertilizers, swimming pool disinfectants and fireworks.


                 Essential steps in planning and preparedness

                                 Local level


                         Conduct baseline assessments


                      Conduct community risk assessments


                          Liaise with the community


                              Draw up local plan


    There are a number of ways in which hazardous sites can be

    *  National hazard inventory. If a national hazard inventory already
    exists (such as that based on the European Seveso II Directive), it
    should be searched for hazardous chemicals or hazardous sites in the
    local community. Depending upon the number of hazardous sites, the
    team may wish to prioritise the local list in order to cope rationally
    with the workload.

    *  Direct local enquiry. The people with the greatest amount of
    information about the types of chemicals present are the site
    operators themselves; and it would seem perfectly reasonable to
    request information about stored chemicals from them. Experience in
    many countries is that this is regarded as commercially confidential
    information, and is not given out. However, it is to hoped that a more
    ethical and community sensitive attitude may develop which would
    enable the release of this information.

    *  Planning enquiries. Typically, local planning regulations in many
    countries will require companies to draw up plans for buildings and
    sites that describe their use. Frequently they are put into the public
    domain, and are sometimes presented for formal public consultation.
    Depending on local arrangements, it may be possible for the local
    authority to search their records to provide details of chemical
    sites, or even of the chemicals to be manufactured.

    *  Local incident surveillance and environmental monitoring.
    Monitoring systems set up to detect the occurrence of incidents or
    changes in the background environmental level of chemicals may
    indicate the types of chemicals being stored or used at sites.

    It should also be remembered that sites include not only fixed sites
    but also transport routes including pipelines, and waste disposal
    sites. Chemical sites may be in danger from terrorist attack on
    the site itself, as well as from being near to other terrorist
    strategic sites, such as armed forced bases or significant civil

     Develop likely / possible incident scenarios For each site
    identified, it will be necessary to identify the chemicals present
    (current and planned) and to develop scenarios of possible releases
    for each one.

     Map out the exposure pathways For each site and substance, the
    vulnerable zone - the area to which the contaminants might be
    transported through air or water - is estimated. This can often be
    done using computer models. It requires a thorough knowledge of the
    topography of the area, the waterways, reservoirs and prevailing
    climate. A map can then be produced of the vulnerable zones.

              predict where released chemicals might travel to,
                        and identify vulnerable sites

     Community vulnerability assessments The populations within the
    vulnerable zone that could be affected are then identified, with an
    emphasis on any especially vulnerable groups (children in schools,
    the elderly in residential facilities, hospital patients etc). It
    should be remembered that the population 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
    motorists, tourists and visitors to entertainment facilities.
    Factors that affect the vulnerability include the amount and quality
    of shelter, the access into and out of the site and the amount of
    training provided.

    Facilities and structures in and around the vulnerable zone that
    provide essential services (e.g. hospitals) and which could be
    disabled by an incident are also identified. Areas where contamination
    would have significant effects such as farmland, water for leisure
    activities or wildlife support, areas for special conservation or with
    endangered species should be considered.

    Assessing the vulnerability around chemical transport routes will
    present greater difficulties. However, it should be remembered that
    highly toxic chemicals are often transported by rail, which by its
    nature, passes through densely populated areas, and by inland

                determine the ability of the local health care
                              facilities to cope

     Health impact assessment This brings together the evidence from the
    exposure pathway and vulnerability stages to calculate the
    casualties - the number and distribution, the type and severity of
    the injuries; any evacuation and sheltering required, the delayed
    effects of acute exposure: the effects of secondary contamination.
    Air dispersion modelling programmes may be used during this process
    (e.g. the ALOHA programme).

     Resource requirements Given the quantity and quality of the health
    effects, it will then be necessary to translate these health effects
    into health care resources required. These requirements are then
    compared against the health care resources available. The team
    evaluates the capabilities of the health care sector, the emergency
    services and the public to respond to (or prevent) potential incidents
    based on current resources, legal safeguards, and existing plans,
    training, and procedures.

       Steps in community risk assessment

    Scenario  -> Pathways    -> Vulnerability  -> Health    
    setting      of exposure    assessment        effects

    An important point to determine is the 'saturation point' of the local
    health care facilities, so as to determine when to call in additional
    help, or refer patients to facilities out of the area. There are two
    ways of doing this: calculate the type and number of casualties that
    the local health care services could cope with, and apply this to the
    various scenarios to ascertain those that would breach them and those
    that would not. The second way is to work forwards from each scenario,
    and calculate the exact numbers of casualties. Total requirements can
    then be estimated, and links established with services in other areas.
    These estimates are by their nature imprecise.

    The health impact assessment brings all these assessments together to
    make a final estimate of the impact of a release of the chemical on
    the health of the population, wildlife, environment and facilities.
    More quantitative methods can be used if resources are available (Risk
    Analysis, Emergency Management Institute, National Emergency Training
    Centre Student Manual SM 305.3, Washington DC USA, September 1990).

    Initiatives to reduce both the risk of an incident occurring, and the
    vulnerability of the population are then undertaken.

    4. Conduct baseline health assessment

    To measure the impact on health (morbidity and mortality) that a
    chemical release has caused, it is necessary to know the background
    levels of illness in the community before the release. Of course,
    levels of morbidity and mortality can change overtime. The purpose of
    the baseline measure is to set up the systems, and to check
    whether the levels are normal or indicate that there are already
    chemical-related health effects. There are two sorts of background
    levels that can be measured.

     General health statistics With the huge number of chemicals being
    produced, the range of potential symptoms that could be produced is
    very wide. Therefore as wide a range of morbidity and mortality
    statistics should be accessed and reproduced as possible. The data
    should include process data, such as general practioner visits and
    hospital admissions, morbidity data such as condition specific
    hospital admission rates, congenital malformation rates, and cancer
    registration rates, and mortality data.

                 it is very helpful if the background levels 
                      of illness are measured regularly

    In most countries, the health statistics will cover populations
    greater than that likely to be affected by a chemical incident, or
    with different geographical boundaries. This can make it more
    difficult to identify any changes in the health of the affected
    population. To increase the power of any epidemiological study to
    detect changes in the health of affected people, routine data should
    ideally be collected from populations around the chemical sites.
    However, this can very expensive, and is usually impractical.
    Nevertheless, for very high risk sites, it may be worthwhile.

                    changes following a chemical incident
                          are more easily identified

    If routine statistics are not available to produce a baseline measure,
    consideration should be given to conducting a one-off survey. Again,
    the resources required to do this will need to be found.

    In addition, it would be very valuable if baseline measurements of
    chemical biomarkers can be taken from the first responders. This is
    because they are the group of people at most long-term risk of
    exposure. Ideally, these measures should be conducted by the
    occupational health services. It is reasonable to freeze the samples
    and only analyse them after an incident, together with a post-incident
    sample. This improves the accuracy.

     Sentinel health events A sentinel health event is a preventable
    disease, disability, or untimely death whose occurrence serves as a
    warning signal that a hazardous environmental exposure may have

    A sentinel health event system uses many of the same datasets as the
    more general surveillance systems described above, but focuses more
    specifically on a limited number of priority diseases and conditions.

    All these diseases and conditions are sufficiently rare and
    sufficiently specific that they suggest exposure to hazardous levels
    of a contaminant and a need for control or further study. Because they
    are based on the International Classification of Diseases (ICD) codes,
    the conditions can be monitored using death certificates or hospital
    discharge data.

                   it can be helpful to collect data about
                      certain chemical-related illnesses

    Sentinel health events include both acute conditions reported for
    individuals (Type 1), and unusual health patterns seen in
    populations (Type 2). For the second category, individual case
    reports are not considered to be sentinel events because the
    conditions are insufficiently specific. However, statistically
    significant excesses of cases in populations over defined periods of
    time, or space-time clusters, suggest the possibility of an
    environmental aetiology. In addition, unusual patterns in particular
    populations, such as the young, population unexposed to other known
    risks, or genetically unrelated individuals living in the same place,
    may suggest a need for further examination of the data.

    Type 1 sentinel health events: conditions reported for individual

    *    poisoning with metals, pesticides, lead, and carbon monoxide.
         Clinical poisoning reports, and biomarkers of exposure (bone or
         blood leads above certain levels) or effect (cholinesterase

    *    cancers specific to physical or chemical agents, such as
         mesothelioma, clear cell cancer of the vagina, and angiosarcoma
         of the liver

    *    precocious puberty - a rare event warranting inquiring into
         oestrogen exposure possibly associated with pesticides,
         industrial chemicals, or food additives

    *    certain blood disorders - methaemaglobinaemia

    *    certain neurological disorders-toxic neuropathies.

    Type 2 sentinel health events: unusual health patterns in a

    *    Bladder cancer in the young, in non-smokers, in humans and their
         pets, in a spatial cluster

    *    Lung cancer in non-smokers

    *    Primary liver cancer in non-drinkers without known exposure to
         hepatitis B

    *    Multiple, excess occurrences of other rare cancers
         (rhabdomyosarcoma, myelogenous leukaemia, acute leukaemia in
         children, acute granulocytic leukaemia in adults)

    *    New asthma in low-risk, non-allergic children in non-smoking
         households (but specificity is low)

    *    New diseases.

    5. Conduct baseline environmental assessment

               collecting regular samples from targetted areas
                for background measurement can be very helpful

    It is just as important to know the baseline levels of chemicals in
    the environment before an incident occurs. Air, water, soil, sediment
    and food in the vicinity of chemical plants should be sampled for the
    full range of chemicals, or their by-products, being manufactured,
    used or stored. Priority areas may need to be selected from the
    community risk assessment, and those areas targeted. It may be
    helpful, for a complete environmental assessment, to predict the
    levels of environmental contamination from a variety of likely release
    scenarios. There are various computer dispersion models available for
    this purpose; although many of the models are unable to adequately to
    take account of all the relevant variables.

    6. Start liaising with the local community

                   bringing the public and local community
                 into the planning systems has many benefits

    The local community is comprised of people who live and work in the
    area that could be affected by a chemical release. It is for their
    protection that all these measures are being taken. It is proper
    therefore that the local community is not only informed about the
    preparations, but is also involved in drawing them up. Community
    members who do help with these preparations must be seen to be truly
    representing their local community. Once an incident has occurred,
    there need to be robust public warning systems for informing the
    public of the incident and any protective measures that they should be

    Liaison itself should not be seen as a one-way process into the local
    community. It should be seen as a three-way exchange, - between the
    local community, the public services and the local chemical industry.

    Some of the methods used to liaise with the public are described
    below. It will be appropriate for some of these meetings with the
    public to be with the chemical industry alone, with the public
    services alone, or with both parties.

                      there are many ways of doing this

     Large public meetings These are the commonest and most familiar way
    of initiating face-to-face discussions with the public. Whilst this
    may be one of the most expedient ways of interacting with the largest
    possible number of concerned people at one time, it is often one of
    the least effective ways to institute a dialogue. However, public
    meetings can be beneficial if the hosting officials are skilled in
    risk communication and work to avoid negative outcomes.

     Public availability sessions Informal, one-on-one communication has
    been shown to be perhaps the most effective way to discuss health risk
    issues. Although very time consuming and resource intensive, a
    personal and confidential discussion between a concerned individual or
    family and a public health / environmental health professional seems
    to reduce many of the barriers to communication described above.

    One way to facilitate such one-on-one communications is through public
    availability sessions. These sessions are hosted by public health
    agencies in the local community; experts are available to talk with
    all interested individuals either by appointment or on a first-come,
    first-served basis. The sessions need to be well publicised in advance
    and staffed by health professionals skilled in risk communication and
    knowledgeable about the local risks. The health professional should be
    conversant with the health effects of the chemical(s) and able to
    assess the potential harm.


                         Liaising with the community


                            Large public meetings


                         Public availability sessions


                          Community Advisory Panels


                                 Mass mailing


                                  The media


     Community Advisory Panels There is a growing recognition in many
    countries that to achieve an effective, long-term solution to the
    public health impact of chemical incidents, residents must be an
    integral part of the decision-making. Experience has shown that a good
    compromise between one-on-one communication and large public meetings
    is the establishment of Community Advisory Panels (CAPS). These panels
    provide the opportunity for an effective dialogue between community
    representatives and environmental / health officials and chemical
    industry representatives. The panels also help ensure continuity over
    a period of months or years, and the opportunity for mutual education.

    In the United States, CAPS have proved to be an effective mechanism
    for government agencies to:

    *    obtain information about the health concerns of the community

    *    establish open and ongoing communication

    *    convey information about government-sponsored health activities
         as they occur

    *    educate the community about the scientific process and educate
         government health officials about the site in question

    *    reach agreement on the measures to be implemented.

    CAPS typically comprise 12 to 15 community representatives, chosen
    either by self nomination or by community organisations. The panels,
    whose members represent the widest possible spectrum of community
    interests, usually meet every 3 months in a public forum. Rules
    regarding the conduct of meetings and issues to be covered are agreed
    upon at the outset and enforced throughout the process.

     Public Warning Systems Some countries and towns have set up a public
    warning system where, for example, a siren is sounded and the public
    listen in to the radio for information and instructions. The public
    will need training and updating in the process. However, it can be
    very effective in high priority areas.

     Other Mechanisms for Public Interaction There is a variety of other
    ways for government officials and the chemical industry to interact
    with people living in environmentally threatened communities
    threatened by chemical incidents.

    Site visits can help the community to appreciate the measures taken by
    the industry to protect the workers and the public. This can help
    reduce anxiety and build trust and confidence.

    Mass mailings are an efficient way to notify residents of a
    concerned community about new scientific findings, planned activities,
    or upcoming meetings. Mailings are most effective when they are done
    in a one-page, "fact sheet" format with bulleted information.
    Information sheets will also be helpful in providing information about
    the priority sites and their chemicals, warning formats and protective
    actions to be taken.

     Other mechanisms These include telephone help-lines, drop-in
    centres, and public training sessions. Radio and television can be
    very important and effective mechanisms, depending on local
    availability. However, it is essential that before any incident
    occurs, a policy is developed and followed, and that relationships
    with the media are developed and well maintained; and that during an
    incident, appearances on radio and television are restricted to a few,
    trained and experienced people.

    7. Draw up a public health chemical incident plan

                     a well developed plan needs all the
                      relevant parties to come together

    The management of a major incident is a complex affair which requires
    the input from a wide variety of organisations and agencies. These
    inputs should be timely and correct. If not, the outcome can become
    considerably worse. Planning (and rehearsals) help to ensure that
    people have developed, understood and learned their roles before any
    incident. Plans are an up-dateable record of those roles - a
    'living' document.

    The planning for major incidents and disasters has been
    comprehensively developed throughout much of the world. In most
    places, there will be a general plan covering major incidents and
    disasters. In addition, there will often be a general plan covering
    the roles of the emergency services in chemical incidents. There will
    also usually be major incident plans in the hospitals, covering most
    types of incidents. However, public health plans to deal with chemical
    incidents are usually non-existent or poorly developed.

    Before starting the process of producing a public health chemical
    incident plan, a decision needs to be taken as to where the plan will

    -    stand alone

    -    integrated into a public health outbreak plan, covering food
         poisoning and infectious diseases

    -    integrated into the emergency services chemical incident plan

    -    integrated into the emergency services major incident plan.

    Whichever is chosen, care must be taken to ensure that the plan is
    co-ordinated with the other relevant but un-integrated plans.

    The public health chemical incident plan will need to cope with four
    different scenarios:


                         The four planning scenarios


                 Detected release, known chemical, fixed site


                Detected release, known chemical, moving site


                      Detected release, unknown chemical


                        Silent release, but suspected.


    *   a detected release of a known chemical from a fixed site -
        this will usually be from a registered hazardous site

    *   a detected release of a known chemical from a non-fixed site -
        such as from a well-labelled road tanker

    *   a detected release of an unknown chemical typically, this will
        occur in releases from sites not on the hazardous site inventory,
        or with unknown combustion products from a chemical fire

    *   a silent release, where the release is unknown or was thought to
        be harmless, but is now suspected from other routes.

    Plans should be developed in close co-operation with and with input
    from all the agencies, specialists, communities, commercial sectors
    and other authorities that the public health / environmental health
    professionals will need to interact with during an incident. The plans
    will also be significantly improved if relevant members of the local
    community are involve throughout the process. Templates of plans which
    have been developed and tested are readily available via the Internet.

    Extensive evaluation of the plan and its implementation should be
    carried out after every incident or training exercise.

    8. Establish access to information, databases and expertise

                           ways of getting hold of
                        information need to be set up

    At the time of an incident, it is vital to have rapid access to data
    about the chemical. It is important therefore that the chemical
    databases are purchased and installed, or 24 hour electronic access
    established well before. The data needed will include information

    *    the physical characteristics of the chemical (this influences the
         way it disperses in the environment and how it enters the body)

    *    the biological tests available to detect exposure and/or adverse
         health effects

    *    environmental sampling techniques and equipment needed

    *    lists of antidotes and decontamination procedures

    *    medical signs and symptoms and methods of treatment.

    People with expertise in these aspects may well be needed to
    supplement the information from the databases. Poisons centres are an
    excellent source of information. Contact is much better made before
    the incident, and this has been described above.

    9. Assess the comprehensiveness of health care facilities

    The availability of adequate local health care facilities, including
    toxiological laboratories, and adequately trained health care staff
    are very important for the successful care and treatment of casualties
    following an incident. Facilities need to be assessed for their
    numbers, medical equipment, decontamination equipment, drugs and
    antidotes, and training.

                       the adequacy of the local health
                        care facilities needs checking

    Where the injuries involve burns or severe toxic symptoms, the local
    health care facilities can rapidly be overwhelmed by even a small
    number of casualties. Access to facilities in neighbouring districts
    or further afield will then be necessary. Identifying where those
    facilities are is an important step in the planning and preparedness

    An alerting mechanism (to the occurrence of an incident) needs to be
    developed and regularly tested.

    10. Pursue measures to reduce the probability of incidents

    The community risk assessment may have identified sites and procedures
    where improvements might lessen the probability of an incident
    occurring. Often, some of these improvements can only be done by the
    company producing, storing or transporting the chemical, and it may
    require a multi-agency team to negotiate these changes.

                      preventive and protective measures
                            should be put in place

    Examples of common improvements are:

    *    an onsite chemical emergency plan coordinated with the local
         chemical incident plans

    *    clear procedures for off-site personnel making deliveries to a

    *    additional training for workers in onsite hazards and routine
         safety procedures

    *    backup systems for evenings / weekends / holidays

    *    regular monitoring of contaminant levels from planned processing
         or releases

    *    regular surveillance and standardised reporting of incidents

    *    improved procedures for product or waste release, or waste
         product containment

    *    improved specifications for vehicles carrying hazardous

    11. Pursue measures to reduce the health effects of incidents

    As well as measures to reduce the probability of an incident
    occurring, there are other preventive measures that can be put in
    place that will reduce the impact of the chemical on the people and
    the environment, should a chemical actually be released. Examples of
    common improvements are:

    *    locating chemical sites away from centres of population

    *    registration of all chemicals in commercial establishments with
         the hazard inventory to ensure rapid identification of the
         released chemical

    *    regular evaluation of plans and their implementation

    *    storage of lesser amounts of chemicals

    *    smaller batch processing

    *    good quality labelling of all chemicals in transit

    *    rapid notification of the chemical incident emergency services in
         the event of an incident

    *    regular surveillance and standardised reporting of incidents,
         including the small "routine" ones

    *    measures to decontaminate land or water already contaminated by
         waste disposal, and to protect the public by education and other

    *    measures to prevent or contain fire-water run-off

    *    introduction of separate drainage ditches or holding tanks to
         contain leaked liquid chemicals.

    Routine activities

    Once the plans and assessments have been completed and put in place,
    there are certain routine procedures that need to be gone through on a
    regular or continuous basis.

    These are:

    *    Recognising chemical incidents

    *    Conducting population health surveillance

    *    Conducting environmental monitoring

    *    Conducting exercises and training

    *    Conducting national incident surveillance and contributing to
         international incident surveillance

    Recognising chemical incidents

                       releases occur in different ways
                        and can be difficult to detect

    Although a few chemical incidents are major ones, and the event is
    self-evident, most acute chemical incidents are small-to-medium
    events, that only the polluter, and anyone directly involved,
    initially knows about. The polluter may not inform the emergency or

    public health services. This will most likely be because the polluter
    feels that the incident can be handled without outside assistance, and
    that the incident is not believed to pose any (appreciable) risks
    outside the facility (on the basis of a rapid initial assessment).
    Other reasons may include the polluter's wish not to be identified, or
    because they do not appreciate (or care about) the personal or public
    health implications. Indeed, the emergency services do not always
    appreciate the possible public health implications.

                various alerting mechanisms need to be set up

    Therefore, and in order for the public health / environmental health
    professionals to be able to help reduce the public health consequences
    of all acute chemical incidents, they need to set up systems that
    will detect the release of the chemicals. Once detected, the public
    health / environmental health professionals will need to rapidly
    assess, judge or estimate whether there is then a risk to the public's

    Detection can occur in seven ways -

    1.   the polluter informs the emergency services who inform the
         public health services. In some cities, a mandatory notification
         system (of all releases) has been established

    2.   observation of a release itself - often as a major event, such
         as an explosion or oil tanker disaster

    3.   information from the public about an environmental change eg
         colour, smell, eye irritation

    4.   ad hoc observation of a rise in an environmental contaminant

    5.   observation of a rise in an environmental contaminant using
         routine monitoring environmental data

    6.   hunches from clinicians and others (e.g. poisons information
         centres) who are presented with a sudden rise in an unusual
         health problem

    7.   observation of a rise in a sentinel health event or other health
         measure, using routine monitoring health data


                           Seven detection methods


                               polluter informs


                              direct observation


                     *non-specific changes -colour, smell


                    *rise in environmental pollutant level


               *rise in routine environmental monitoring levels


                              *clinical hunches


                  *rise in routine health monitoring levels
                       *requires public health activity
                           to setup alerting systems



    Most of these methods require members of the community to become more
    aware of the possibility of a chemical incident and then to know what
    to do if their suspicions are raised. This 'toxicovigilance' has to be
    developed and encouraged in a wide variety of people and
    organisations, such as accident and emergency staff, primary care
    doctors and nurses, infectious diseases doctors and community
    investigators (because chemical incidents can mimic outbreaks of
    infectious diseases), poisons information centres, epidemiologists and
    public health / environmental health institutions, and other groups
    receiving reports of potentially toxic events. Members of the chemical
    industry need to be encouraged to report all acute chemical incidents,
    however small.

    Once a suspicion has been raised, the person needs a quick and easy
    route to alert the emergency services and the public health chemical
    incident management team. A toxicovigilance programme therefore

    *    The public, local institutions and organisations, and all members
         of the emergency, environmental and health services to be
         regularly encouraged to be alert to the possibility of chemical
         incidents, and to be educated on the means of communicating
         rapidly with the emergency services and the public health
         chemical incident management team

    *    A well-publicised, twenty four hour incident telephone line,
         and a network co-ordinator always available

    *    A surveillance and monitoring system.

    Conducting population health surveillance

    Once the baseline health assessment has been completed, routine
    surveillance needs to be established. Routine population health
    surveillance is the ongoing and systematic collection, analysis and
    interpretation of health data in order to:

    *    identify a health event that may be related to an unknown,
         acute release of a chemical

    *    monitor trends in the different types of health status

    *    stimulate epidemiological research likely to lead to control
         or prevention

    *    permit assessment of the effects of control measures

                 routine collection of health data helps in 
                identifying trends and incidents, stimulating
                   research, and auditing control measures

    The same set-up for health surveillance will be required as for the
    baseline health assessment, that is access to regularly updated
    general health statistics and to regularly updated sentinel health
    events. There are certain attributes that any surveillance system
    should fulfill:

    *    Simplicity

    *    Flexibility

    *    Acceptability

    *    Sensitivity

    *    Predictive Positive Value

    *    Representativeness

    *    Timeliness.

    The essential features of each system are described below.

    General health statistics

    Data from a wide variety of routine sources need to be collected,
    collated and presented in a way that allows trends and comparisons