A true hazardous substances emergency is best managed by a specialist with training in toxicology but such specialists are in short supply and may not be on the scene when an incident occurs. Hazardous substances are compounds and mixtures which pose a threat to health and property because of their toxicity, flammability, explosive potential, radiation, or other dangerous properties. Public attention tends to be drawn particularly to carcinogens, industrial waste, pesticides, and radiation hazards, but there are innumerable compounds which do not fall into these categories that can pose a threat to the public safety and health. Gasoline, for example, can explode with the destructive force of gunpowder. Although hazardous substances incidents take many forms and may be highly individual, the great majority seem to involve a relatively narrow range of hazardous substances: solvents, paints and coatings, pesticides, acids and alkalis, and metal solutions.

Table 24.1 provides a checklist of questions to be asked in the event a physician is called to assist in managing a hazardous substances incident. A careful, methodical approach and clear, concise statements to the authorities and to the public are in some ways more important than detailed knowledge of the toxicology and safety hazards involved but one should always find out as much as possible before offering an opinion which may affect the management of the situation.

At the very beginning, one absolutely needs the most accurate information possible. What hazardous substances are involved? What are their toxic and safety hazards? How many people have now been exposed and how many may be exposed in the near future? Among these people, are there likely to be any in the community who may be at exceptionally great risk (which may include the very young, the very old, the ill and the susceptible as a result of a condition such as pregnancy or an illness such as asthma)?

1. What toxic and hazardous substances have been identified?

1.1 At what concentrations in air, water, and soil?

1.2 What are the known health hazards at these concentrations?

1.3 What are the potential hazards of fire, explosion, or chemical interaction?

2.1 What groups in the exposed population are likely to be most susceptible to health

effects?

2.2 How many exposures are resulting in hospital admissions? Outpatient visits?

2.3 What clinical findings, if any, are being observed?

4. Is the community adequately handling the casualties?

4.2 Should hospital disaster plans be mobilized?

4.4 Are local physicians experienced and knowledgeable about this kind of problem?

If not, what is the best way to reach them quickly?

Never guess in a public situation as, when being interviewed by the press or at a public hearing.

From these preliminary data, the physician may have to decide the magnitude of risk to the population and the appropriate medical response. The physician involved must be prepared to constantly revise his or her opinions. It is a good practice to keep a log during an incident. Pertinent information can be kept in one place in this log and each entry can be dated and timed, and the source of the report identified.

Correct identification of the substances involved is important and requires technical expertise. Labels on drums may be misleading because these drums are often recycled. Samples should be taken by an occupational hygienist using suitable personal protective equipment and transported safely to a suitably equipped laboratory certified for such work. Unless there is a compelling reason to act, such as a fire or a rapid leak, it is usually wisest to let the material sit undisturbed than to act on one's own, until it is identified and suitable precautions can be taken. Analysis, evaluation, and clean-up of a hazardous substances site is expensive when done on a routine basis, but becomes extremely expensive on an emergency basis. Commercial firms specializing in these operations are few and may have to travel long distances, adding to the cost. If an emergency forces action before the material is identified, the only prudent move is to assume the worst unless one has exceptionally strong circumstantial evidence that the material is not highly toxic.

When a material is known, the hazard potential must be determined. Users of any hazardous material are required to keep on file a Material Safety Data Sheet (MSDS) prepared by the manufacturer. MSDS's usually give reasonable information on the safety hazard of chemical formulations, but they are almost always incomplete descriptions of the compounds' toxic effects. Since many chemical formulations are proprietary mixtures, the MSDS may not identify specific chemicals or their proportions. Table 24.2 provides a list of telephone numbers for emergency calls to determine the hazard or toxicity of substances that may be involved in industrial emergencies.

Determining the number of residents and employees at risk requires only a general estimate at this point. Not everyone in the community will actually be exposed, of course, and for purposes of planning a medical response, it is important to consider the characteristics of the persons who may actually come into contact with the material. Knowledge of the community at risk allows one to alert local health providers in advance and to warn susceptible individuals to take protective measures.

1. National Response Center, U.S. Coast Guard (24 hour)

800 424-8802 Used in USA only

202 267-2675 To report hazardous wastes from Canada

2. CHEMTREC, Chemical Manufacturers Association

800 424-9300 Used in USA only

800 424-9346 Used in USA only

4. American Medical Association, Department of Public Health.

 

312 645-4538 USA or Canada. This department could provide information on health affects of chemical hazards. (Would call National Library of Medicine as a reference if needed.)

 

 

5. CANUTECH, Transport Canada (24 hours, collect).

The next step is to establish control over the situation in order to minimize the potential for exposure. This requires teamwork between police, fire, and public health authorities and obviously varies with the nature of the incident.

In a simple case of sealed drums at an illegal or abandoned dumpsite, a commercial hazardous materials hauling company can be hired to perform an initial evaluation and to remove the waste to an approved disposal site. Until this is done, the area should be cordoned off with barricades with entry restricted to authorized personnel.

In more complex situations, coordination is essential. Fire departments are best equipped to handle safety hazards but need advice and assistance in dealing with toxic materials. The most difficult situations, such as fires involving multiple toxic substances, known and unknown, pose serious threats to public safety personnel and may require an on-site medical presence.

In extreme situations, evacuation may be unavoidable. Large-scale population evacuations are very rare and carry a high cost in stress and safety problems. Medical assistance stations may be needed.

An important aspect of containing the problem is to prevent public over-reaction. Any incident provokes rumors and misinformation which must be controlled to avoid panic or misguided interference in public safety measures.

An important role for the medical officer is the protection of workers engaged in clean-up and control activities at the site. They should be equipped with suitable protective gear, decontamination procedures, back-up personnel, emergency telecommunications from the site, and the presence of a site work plan that includes proper security and emergency provisions.

Medical emergencies involving hazardous substances are less common than ambiguous exposure situations in which a person has been or is believed to have been exposed to a toxic substance and requires a medical evaluation. When the substance is known, an appropriate medical evaluation can be derived from many of the references given at the end of this book. When the substance is not known or involves a complex mixture, the appropriate medical evaluation may be difficult to determine.

In a complex or obscure situation where the identity of the exposure is unknown or in doubt, the clinician should at least consider the possibility of acute effects involving those organ systems most commonly involved in toxic injury: the respiratory, renal, hepatic, dermatologic, and nervous systems. Many incidents involve multiple exposure or substances which have multiple effects. Thus, it is good practice to provide a basic comprehensive evaluation even when a patient presents with a specific clinical complaint. Table 24.3 and 24.4 outline a reasonably comprehensive clinical evaluation strategy for patients presenting with a history of possible exposure in such circumstances.

In serious hazardous substance emergencies in which injuries or illnesses have been sustained in the community outside the plant the most valuable service that can be provided to health care providers by occupational health service personnel is to furnish regular, accurate bulletins on the extent of the problem and the appropriate management of incident-related cases. In complex or particularly widespread incidents, it is very useful to establish a central registry of individuals exposed. This registry can become invaluable for future epidemiologic studies, to establish eligibility for disability benefits at some future date, and to establish intent in facing later legal action.

The mental health consequences of a major industrial emergency are often serious. Unlike natural disasters, such as earthquakes and hurricanes, manmade disasters are very difficult for communities to cope with because they are subject to often divisive speculations on guilt, differing opinions on responsibility for compensation, suspicions that victims are exploiting the situation, and a sense that those affected are contaminated, especially when the incident has involved toxic exposures and there is anxiety or a real question regarding; future risk of cancer. The victims often feel alienated from their former friends and neighbors, who may feel that any action taken against the interests of the responsible company could lead to economic loss for the community. As well, litigation tands to be prolonged and bitter in such incidents, magnifying the divisive effects. Counselling and preventive mental health interventions are very valuable in such situations.

Many steps can be taken on the local level to prepare for an incident and to reduce the likelihood of a hazardous substances emergency. An inventory of likely sites where an incident might occur is particularly important in developing such a plan, along with a frank and realistic assessment of the capability of local authorities to deal with such problems and a regularly updated list of agencies and commercial firms available for backup and laboratory services.

A system for communicating with local physicians and health facilities quickly should be developed by a telephone tree, telegram, or mail, depending on the urgency of the situation, the number and dispersion of physicians in the community, and what systems may have been set up beforehand. Of equal importance is a system for disseminating accurate information to the public. This may include a rumor control committee composed of community representatives regularly briefed, a telephone hotline, reports to community groups, and regular press conferences. Slight differences of opinion, interpretation, and understanding can come across as confusion, uncertainty, and rivalry. It is therefore particularly important to funnel all public information whenever possible through a single spokesperson.

1. Complete Medical history, emphasizing the following:

1.1 Current medication

1.2 Skin disorders, chronic and acute

1.5 Renal disease, chronic and acute

1.6 Cancer

17. Pregnancy

2. Complete physical examination, emphasizing the following:

2.1 Skin (irritation, dermatitis)

2.2 Lungs (bronchitis and bronchospasm)

2.3 Liver (evidence for early chemical hepatitis)

2.4 Neurological examination (evidence for peripheral or central neurotoxicity)

2.5 Pregnancy

3. Laboratory studies:

3.1 Urinalysis, chemical and microscopic

3.2 Serum Creatinine

3.3 Liver function tests: SGOT, SGPT, bilirubin

3.4 Chest film

3.5 Pulmonary function tests

3.6 Blood cholinesterase, if organophosphate pesticides may be involved

Topic Response Test^a Confounding factors Follow-up Tests

______________________________________________________________________________

Dermatitis Physical Exam Any cause of rash Physical examination^c

Respiratory injury^b Chest film Acute and chronic Chest film^d

Pulmonary respiratory disease Pulmonary function tests^d

Bronchoprovocation challenge

Hepatotoxicity Liver function Hepatitis of any cause, Repeat tests

tests alcohol consumption

Nephrotoxicity Urinalysis Chronic or acute Urinalysis^c

Serum creatinine renal disease Serum creatinine^c

Neurotoxicity Neurological exam (Many) Neurological exam^c

Carcinogenicity (None) (Many) Reporting system^e

Reproductive Fetal ausculatation (Many) Pregnancy

______________________________________________________________________________

a Perform on second or third day after exposure.

b Significant respiratory injury is usually associated with symptoms at the time of

exposure or shortly thereafter.

c Repeat in one or two weeks if screen is normal, but exposure documented.

d Repeat in one or two months if screen is normal, but exposure documented.

e There is no sure way to predict individual risk of cancer; latency period after

exposure is measured in decades.

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