Laura S. Welch
David W. Blodgett
As we enter a new century, we continue to have widespread proliferation of new and potentially toxic chemicals. These hazardous exposures are encountered in homes, schools, the general environment, and especially the workplace. The extent to which such exposures may be causing health problems is a grave concern. Few communities in the United States have escaped public concern over the health hazards of pesticide spraying, asbestos in school buildings, contaminated drinking water, electromagnetic radiation, and toxic waste disposal.
This chapter provides an overview of how environmental diseases occur and outlines an approach for recognizing and addressing them. It emphasizes the workplace, where environmentally induced illness is most commonly recognized. A good estimate is that there are a total of 55,200 U.S. deaths annually that are a result of occupational disease or injury (range: 32,200 to 78,200) (1). Occupational deaths are the eighth leading cause of death in the United States, ahead of suicide (30,575) and greater than the annual number of motor vehicle deaths per year (43,501) (1). Additional occupational illnesses that do not result in death may number an additional 300,000 per year (1,2). Hazardous exposures and resulting illness also occur in the home or community environment. The same principles that apply to workplace exposure also apply to home and community exposure.
Vital Role of Primary Practitioners
Primary practitioners are often the first professionals to recognize the hazards of occupational exposure and to document the link between their patients’ illnesses and their patients’ work. The task of controlling the hazards usually involves public health specialists, but it is vitally important that primary practitioners take the time to report and followup suspected occupational diseases.
Although the United States has for three decades had the Occupational Safety and Health Administration (OSHA) to ensure workplace safety, there are only enough inspectors to visit every workplace once every 100 years. Each year still brings efforts in Congress to weaken the program that does exist. Locked fire exits, exploitation of immigrants, child labor, and sweatshop conditions persist decades after the New Deal took steps to abolish them. Many workers are unaware of their right to request an investigation of potential hazards at work, and concerns for job security deter them from raising complaints about safety with supervisors. Public health surveillance of occupational and environmental disease has been improved by the efforts of the National Institute for Occupational Safety and Health (NIOSH) working with state health agencies, but it remains limited in scope and coverage. For all these reasons, if a patient has an occupational health problem or is exposed to a dangerous situation at work, the patient's physician may be the single most important factor in protecting the patient's and the community's health.
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Pathogenesis of Occupational Disease
The pathogenesis of occupational disease is complex and involves not only the interaction between the host and a toxic exposure, but also a complex set of social interactions.
Toxin–Host Interaction
For an occupational disease to occur, there must be a triad consisting of a toxic agent, a host, and an environment in which the host is exposed. The illness that may result depends on the toxic properties of the substance or energy source, its route of entry, the dosage received by the host, and the susceptibility of the host to the toxin.
Toxic agents can be inhaled, ingested, or absorbed through the skin. With inhalation, the dosage received depends on whether the substance is present as gas, a fume, or a dust. Deposition of dust in the lungs depends to a great extent on particle size and distribution, because smaller particles can more easily enter the alveoli and become trapped. The concentration of the substance in the air (which is related to room ventilation, temperature, and humidity), the rate at which the worker is exercising and breathing, and protective factors such as special clothing or respirator use are other factors that affect the amount of toxin absorbed.
Once the toxic substance is absorbed, there may be an instantaneous effect (as in the case of carbon monoxide poisoning), a brief latent period (as in the case of occupational asthma), or a latent period of years or decades (as in the pneumoconioses). A brief, high-dose exposure may cause serious illness and death and be easy to recognize. Prolonged exposure to a low dosage of a toxin may not cause symptoms at the outset but may produce disease years later.
Impact of Economic and Social Factors
Thousands of new chemicals are introduced into industrial processes every year, but few have been tested to determine their potential toxicity. Even when toxicologic screening tests are done on a compound, they may not predict human disease. Despite the implementation of the Toxic Substances Control Act (TOSCA), which gave the U.S. Environmental Protection Agency (EPA) authority to require pretesting of chemicals, in too many cases, the hazard of a chemical is recognized only after an outbreak of illness. Economic factors play a major role in determining how safe a workplace is. Industrial hygiene programs to monitor exposure are common only in the largest plants. Important decisions, such as improving ventilation or decreasing exposure to noise, may involve significant expense. Workers may be reluctant to complain about working conditions for fear of losing their jobs. This is especially likely during periods of high unemployment, when acceptance of unpleasant and potentially unhealthy working conditions may be the price of having a job. Even when workers are strongly organized, the desire for a safer workplace may be balanced by a concern that increased production costs may result in the decision of a company to relocate its plant to areas where unions are less effective or do not exist. Such anxieties have been heightened by the globalization of manufacturing. Stringent health and safety regulations, with strong enforcement, can put competitors on a more equal footing and protect responsible businesses from being undercut by irresponsible ones.
Diagnosing Work-Related Disease
Although episodes of illness caused or exacerbated by the patient's work are often seen in ambulatory practice, they frequently are not recognized as such. Misdiagnosis of an occupational disease means that the patient does not benefit from correct diagnosis and management and there is no correction of the poor working conditions that may subsequently injure others or even result in death. Two cases illustrate these points.
Case Study: A Teenager with Bronchitis
An 18-year-old woman complained to her physician of a severe cough and some wheezing. The physician treated her with erythromycin and fluids and advised her to stay in bed for a few days. She recovered and returned to work feeling well. Several days later she had a severe recurrent cough with wheezing and dyspnea and saw her physician again. The physician again prescribed erythromycin and rest. She remained off work for a week. She felt better and returned to work. After 2 days she became extremely short of breath and was brought to the emergency room. She had severe bronchospasm and was admitted, improving on bronchodilators and corticosteroids after a few days. An occupational history on admission disclosed that her work involved grinding drill bits made of tungsten carbide containing a small amount of cobalt, a known pulmonary sensitizer. Once the patient was sensitized, each fresh exposure to the dust caused symptoms after a shorter incubation period. Had the first physician considered the diagnosis of extrinsic asthma and inquired about occupational exposures, the patient's subsequent deterioration could have been prevented.
Case Study: A Man with Severe Abdominal Pain
A 28-year-old man presented to the emergency room of a community hospital with a chief complaint of severe abdominal
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pain. There was significant abdominal tenderness with a question of guarding. He reported having seen his family physician on two occasions during the preceding 2 weeks, with severe cramping pain felt around the umbilicus. His physician had prescribed a H2 blocker and tried to schedule a gastroenterologic consultation, which the patient had not set up because of difficulties with his work schedule. The pain that had been intermittent had now become constant, more in the lower quadrants, and more severe for longer than 6 hours. Blood work showed a normal amylase level and a leukocytosis. A surgical consultant suggested the possibility of an appendiceal abscess but believed that the patient was stable enough to await the results of a computed tomography scan. A gastroenterologist was consulted and was the first physician to take an occupational history. The patient had been a painter for several years and was currently working for a contractor repainting the elaborate metal cornices of a building. For more than a month he had been using a vibrating tool to remove old paint, and this created a lot of dust. He did not know whether lead was in the paint. The gastroenterologist suggested a determination of the patient's blood lead concentration and watchful waiting. The computed tomography scan was normal and the blood lead concentration was elevated. Several coworkers were also poisoned, and the patient's son had an increased blood lead concentration from the contaminated work clothes his father had brought home.
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TABLE 8.1 Components of an Occupational History |
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To avoid the pitfalls these cases demonstrate, the following three strategies are fundamental when evaluating a patient:
Taking an Occupational History
Inquiring about a patient's job not only helps identify occupational disease but also provides other information useful in caring for a patient. Clearly the physical demands of the job are important when advising a patient about a health problem such as coronary artery disease or diabetes mellitus. Knowing the patient's work schedule is also important, because shift work affects medication schedules, diet, and family life. Medications can dramatically affect the patient's comfort or safety at work (e.g., diuretics in an interstate truck driver, antihistamines in a construction worker who works at elevation). Financial and psychological stress may result from layoffs, whereas regular overtime may bring about chronic fatigue and psychological problems of its own. Usually, a brief discussion of the current job, including a brief description of how the patient spends the working day, is sufficient. This rarely takes more than 3 minutes. Table 8.1 summarizes the major points to cover in this inquiry.
When some aspect of the medical or occupational history raises suspicions of a work-related condition, further questioning flows naturally. The inquiry should focus on a temporal relationship between symptoms and possible exposure, exposure to an agent known to cause disease, or a pattern of similar illness among coworkers. Because every patient, every job, and every medical presentation is different, there is no single way of taking a history. If the patient uses jargon or job titles that are unfamiliar, it is important to ask for clarification.
The screening history sometimes reveals the need to take a lifelong work history. An account of previous jobs and exposures is especially important when the patient has a chronic illness or the possibility of work-related neoplasia. In such cases, the following approach is recommended (it may save time to have the patient bring this information, written out, to a followup visit after the initial evaluation):
Diseases That Are Commonly Related to Work
The occupational diseases that physicians encounter depend on the industry in the immediate vicinity and the demographic makeup of their practice. For example, practitioners caring for the elderly may see retired workers with previous exposure in all types of industry. Any organ system can be affected by hazardous exposures. Table 8.2 lists
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clinical problems grouped according to the organ system affected.
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TABLE 8.2 Common Medical Problems with Examples of Environmental Causes |
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Dermatitis and pneumoconiosis are the most commonly reported occupational illnesses. This probably reflects both true incidence (skin and pulmonary epithelium being most in contact with the outside environment) and the greater likelihood of recognition of these disorders as occupational in origin.
The number of chemicals that are toxic to the liver and kidney is so great that a careful exposure history should be taken from all patients with unexplained hepatitis or hepatic or renal failure. Many chemicals can affect the gastrointestinal tract and cause functional disturbances that may be misdiagnosed as peptic disease or irritable bowel syndrome.
Low-level exposure of the respiratory organs to a variety of substances may result in the production of nonspecific upper respiratory tract syndromes that the patient may describe as an intractable cold or as sinus trouble.
Occupational diseases sometimes manifest with striking and unusual signs (e.g., acro-osteolysis in vinyl chloride workers, nasal septal perforation in patients exposed to chromates). More commonly they cause vague systemic symptoms typical of early intoxication or manifest as a disease of ordinary life, such as asthma or eczema.
The following specific clinical situations should always raise the consideration of an occupational or environmental cause:
Determining Work Relatedness
The key to identifying occupational disease is to be sure that a toxic or environmental etiology is at least considered. In addition, the patient should always be asked, “Do you think this problem could have anything to do with your work?” and, “Does anyone else at work have this same problem?” Very often, if there is a connection, the patient will be able to identify it.
If neither the physician nor the patient knows whether a syndrome is occupational in origin, resources are available that identify toxic causes of a given symptom complex, toxic exposures of given occupations, and the potential hazards of exposure to given substances (Table 8.4).
FollowUp of Occupational Disease
Physician's Role
If there is suspicion that a patient became ill from an occupational exposure, it is the physician's responsibility to followup. Not only does diagnosing an occupational disease affect therapy and eligibility for compensation for a patient, but it may indicate that the health of others is also in danger. Often physicians overcome their own uneasiness about a patient's job by advising the patient to change jobs. Then, instead of the potentially hazardous job being made safe, another unsuspecting person is brought in to take the risk.
In some circumstances, occupational disease is recognized but the original hazard has been eliminated (e.g., in a patient with asbestosis who worked in a now-closed shipyard). Even in these circumstances, former coworkers need to be informed of the risk resulting from previous exposure.
It is not necessary to wait for absolute proof of etiology before beginning an investigation of a possible workplace hazard. The least-severely affected member of a group of workers may be the one who seeks attention. Moreover, for most occupationally induced diseases, proof of a relationship rests on epidemiologic data rather than on diagnostic study of the individual patient. Often the most practical way to learn whether a patient's problems are caused or exacerbated by his or her occupation is to find out whether coworkers are similarly affected. If the physician identifies
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a possible occupational illness, assistance from others can be sought.
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TABLE 8.3 Cancers Known to Be Caused by Environmental Agents |
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Investigative and Enforcement Agencies
State Level
Many states have a health department unit for investigation of occupational disease. Some states require physicians to report all cases of suspected occupational disease. Reporting any suspected occupational disease problem to the local health department can be the first step in followup. In many states, NIOSH assists the health department in surveillance and control of specific occupational diseases.
Federal Level
If there is difficulty in clarifying the potential relationship of illness to environment, or if the concerns raised are not addressed by a specific OSHA regulation (see Enforcement Agencies), it may be helpful to request assistance from NIOSH. This institute is the part of the United States Public Health Service (USPHS) Centers for Disease Control and Prevention that conducts research on occupational disease. An employer, a union, or any three employees can request a formal health hazard evaluation
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(HHE) of a workplace. Furthermore, NIOSH has educational resource centers (where consultants are available to help physicians, employers, and workers) in each region of the United States. These centers can provide literature searches and information on available publications and current areas of research, and can refer a physician to others who are experts in the field. Access to regional centers can be provided by the central office.
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TABLE 8.4 How to Determine the Potential Hazards of an Exposure |
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In addition to its investigative function, NIOSH can assist a physician directly in investigating a patient's exposure. Its clearinghouse responds to practitioners’ inquiries with information about the hazards of particular trades and toxic substances. Table 8.4 has contact information.
Enforcement Agencies
Although health departments generally have authority to investigate occupational diseases, regulation of workplace conditions is usually the responsibility of a separate state agency or the local OSHA office in the United States Department of Labor (http://www.osha.gov/fso/osp/index.html). When a state takes over OSHA enforcement, its regulations are required to be as strict as the federal regulations. In every state, every employer is obligated to report workplace-related injuries and illnesses to OSHA.
If other workers may be in imminent danger of being made ill, the physician should communicate this urgently to OSHA and request an immediate investigation. In most cases, OSHA enforcement officers can determine easily whether regulations are being violated at a workplace, and they will provide a followup report to the referring physician. In some cases, the inspection suggests that the patient's illness was job related but that at the time of the inspection no specific OSHA regulation was being violated. If a continuing hazard does exist, OSHA can require changes because the employer has a general duty to maintain a safe workplace. Especially in these situations, physicians may need to be patient but persistent to see that appropriate action is taken.
The Mine Safety and Health Agency (MSHA) is the specific federal agency with responsibility for safety inspection and enforcement of occupational health standards for the mining industry (http://www.msha.gov/).
Consultants
Consultants who are particularly knowledgeable about specific problems are increasingly available to help practicing physicians. Poison centers, through their national network of contacts, can usually identify an appropriate expert for telephone consultation about an acute problem; you can find your local poison center through the American Association of Poison Control Centers (http://www.aapcc.org/). The Association of Occupational and Environmental Clinics (AOEC), a national network of primarily university-based clinics, can be contacted to identify resources available in most parts of the United States (Table 8.4).
Evidence-Based Practice
The Cochrane Library now has a section, the Cochrane Occupational Health Field, that provides evidence-based reviews of occupational health practice (see http://www.hopkinsbayview.org/PAMreferences).
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Workers’ Compensation Programs
Every state has a workers’ compensation act that provides a system to pay for medical expenses related to occupational disease and injury and for employees’ lost earnings. These acts were passed to provide a no-fault system of compensating workers injured on the job and to provide employers with statutory protection from being sued for negligence by their employees.
Although the system sometimes works well for on-the-job injuries, it does not respond well to the needs of a worker with an occupational disease. Here the burden of proof that the disease is work related falls on the worker, and the process of obtaining compensation is often slow and difficult. Because most small employers insure themselves with an insurance company, the insurer may delay action on a claim even when the employer believes the illness was caused by the job. Usually the worker can obtain legal assistance without having to pay an attorney in advance, because provision is made for cases to be taken on a contingency-fee basis (i.e., attorneys receive no fee unless the claim is upheld, and then they receive a fixed percentage of the award). Because illness claims are usually complex, the worker often needs a lawyer.
If a physician concludes, or even strongly suspects, that a patient has an illness caused by or made worse by the patient's job, the patient should be encouraged to file for workers’ compensation (through the employer, the workers’ compensation local office, or a lawyer).
If a claim is pursued and won (even though it takes time), the patient is usually guaranteed lifetime medical coverage from workers’ compensation funds for that illness. Compensation may lift some of the financial burdens from the patient and the patient's family, particularly in cases of chronic or fatal illness.
To some extent, the workers’ compensation system has failed because of inadequate physician diagnosis and follow-through. Most of the economic and social costs of industrial disease are borne not by the companies that may have acted irresponsibly but by the victims and the taxpayers, including businesses that are trying to protect their employees properly. A 2005 report from the RAND Corporation found that about one-third of all disabled people in their fifties receiving benefits from Social Security Disability became disabled because of their jobs; this proportion was 50% among the men.
Physicians are often reluctant to become involved with workers’ compensation, believing that a claim may tie them up in court. This is an unsubstantiated fear, because the medical record usually provides sufficient medical evidence and the physician does not have to appear at the hearing. If the record does not provide adequate information, the attorneys involved are almost always willing to take a statement at the physician's convenience. Physicians should note, however, that many patients are reluctant to file for workers’ compensation because of fear of reprisal, lack of management response to prior reports, and a desire to stay in their usual job rather than being transferred to a different job because of a medical condition (3).
Part-Time Occupational Health Physician
A primary care practitioner may become involved in a workplace at the invitation of the employer or the union representing the employees. Many small- and medium-size workplaces need the assistance of part-time physicians to conduct effective programs to detect and prevent occupational disease. A physician who takes on an occupational health role should become thoroughly acquainted with the goals and procedures of the proposed program, as well as the applicable regulations. Table 8.5 lists the principal responsibilities that an occupational physician
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might be asked to assume and the sources of regulations that guide these physician responsibilities. The American College of Occupational and Environmental Medicine (ACOEM; http://www.acoem.org) sponsors regular training sessions to keep its members and interested physicians up-to-date in these roles.
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TABLE 8.5 Responsibilities for the Part-Time Occupational Health Physician |
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Some physicians in occupational medicine regard themselves as responsible to the management of the company that pays them, rather than to the patients they serve. In some instances, physicians have withheld information from patients about work-related diseases. In other cases, physicians modify their therapy for illnesses and injuries to meet the needs of production rather than the needs of the patient. Both the ACOEM and the International Labour Organization (ILO) have developed ethical guidelines for occupational physicians, and many abuses have been ended. Table 8.6 summarizes the principal ethical responsibilities of an occupational health physician as outlined by ACOEM.
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TABLE 8.6 ACOEM Code of Ethical Conduct |
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Physicians and Health Care Institutions as Employers
Promulgation of the OSHA Blood-Borne Pathogens Standard has reminded physicians and health care organizations of their responsibilities to those they employ and supervise. Most hospitals and state and local medical societies have available information and instructional material to simplify compliance with the requirements for protective equipment, immunization, and education. The basic components of universal precautions to protect health workers from infected body fluids are summarized in Chapter 39, and postexposure actions to address the risk of acquiring hepatitis or human immunodeficiency virus infection are summarized in Chapters 18 and 39, respectively.
Hazards at Home and in the Community
Exposures at Home
The average American home is a Pandora's Box of potentially harmful exposures. Between kitchen, bathroom, garage, and garden, family members may have access to caustics, a variety of aerosols, pesticides, solvents, paint removers, adhesives, and electrical equipment. These types of exposure should be considered when warning about childproofing for toddlers and when evaluating dermatoses and allergic reactions. Exposures at home may also produce illness in ways that come less readily to mind (Table 8.7). Case reports document poisoning from inappropriate use of cosmetics and vitamin supplements. Many hobbies can involve exposure to chemicals with fewer protections than workers in industry enjoy. For example, lead poisoning has been documented from ceramics, stained glasswork, and cosmetics; paint strippers containing methylene chloride can produce carbon monoxide poisoning sufficient to aggravate angina and precipitate
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infarction; and injudicious combinations of cleaning materials can release hazardous fumes. Homes themselves may have hazards. For example, lead-containing paints are a risk to both children and do-it-yourself enthusiasts, and formaldehyde-urea foam insulation can release sensitizing fumes. In cases of illness caused by such exposures, physicians need to take a careful history to recognize the cause.
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TABLE 8.7 Common Hazards at Home |
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Heating and ventilation systems deserve special mention. Even up-to-date heating systems can produce carbon monoxide poisoning if flues are blocked or inadequate air for combustion is provided. Because symptoms of early carbon monoxide poisoning are nonspecific and mimic those of stress and depression, a high level of suspicion is critical, especially early in the heating season. With the current emphasis on increased insulation and barriers to air infiltration, houses are often poorly ventilated by fresh air. The increasing use of wood, coal, and kerosene heaters may make matters worse. Use of scrap lumber treated with chemical preservatives is an additional hazard.
Leaking roofs and windows can lead to water damage to ceilings and walls. Condensation onto concrete slabs under carpet also can cause damp conditions. Water damage is the major cause of disruption of lead-containing paint and can give rise to significant growth of mold.
Office and commercial buildings are also increasingly tight, as heated or cooled air is recycled. Many epidemics of illness caused by chemical or biologic agents circulated through the air are being reported. Building-associated illness can be caused by exposure to particulates, chemical fumes from cleaning materials and office equipment, and mold spores or other biologic antigens. Because symptoms are often nonspecific, diagnosis may depend on recognizing a temporal pattern or symptoms in coworkers. Evaluation of the ventilation system often reveals inadequacies, and in many situations, improved ventilation may be all the therapy that is needed.
Exposures from Sources in the Community
Physicians are increasingly being asked for advice relating to concerns about contaminated drinking water and air and the cleanup of toxic wastes. Many communities dependent on groundwater have had their supplies threatened by illegal dumping of chemicals or by leakage from licensed landfills.
There is no substitute in such situations for enlisting the assistance of appropriate experts, and physicians in a community may be expected to take the lead in getting help from state and local agencies. Often there is a continuing role for practitioners to play in facilitating the resolution of problems. In many cases, knowledgeable specialists have difficulty in translating what they have to say into language that the lay public can understand. Physicians who spend a good part of their days translating medical science into advice for their patients in the office are well suited to serve in this role. At the same time, community members may need someone who can represent their acute personal concerns to the authorities in a reasoned way. A physician can serve as advocate and critical reviewer for the community by making sure that the statements and positions of all of those involved are supported by factual evidence and by calling on independent expertise when appropriate. The Agency for Toxic Substances and Disease Registry of the USPHS has made a commitment to support physicians in communities affected by environmental contamination with information and assistance. Emergency help is available 24 hours a day by telephone at the Centers for Disease Control and Prevention (CDC) Emergency Operations Center, 770-488-7100.
Air Pollution
Patients with respiratory disease are especially concerned about the effects of air pollution. Patients often develop symptoms of respiratory tract irritation during periods of severe pollution, and patients with cardiac or respiratory disease may suffer exacerbations. Prudent advice is called for in such situations. Advice to move to less-polluted areas is rarely practical, and such advice should be given only after a great deal of thought about the impact of a move on the patient's entire life. Durable solutions to problems caused by air pollution depend on efforts to limit industrial discharges and, importantly, the emissions of automobiles. Pollution of indoor air in workplaces and in public facilities from cigarette smoking is an equally important challenge to the medical profession and to each community. In recent years, the increase in smoke-free public places has significantly reduced exposure to this form of air pollution. In most states, the American Lung Association is leading the struggle for clean air.
Hazardous Materials: Accidents and Disposal
Physicians with no special background in toxicology or public health may be pressed into service in cases of accidental emissions of toxic fumes or of accidents involving transport of hazardous materials.
In responding to such emergencies, a practitioner should clarify immediately that the hazard is being contained as effectively as possible, that people not needed at the scene are not being exposed, and that orderly procedures for the care of casualties are being set up. Many communities have developed a coordinated plan for response to hazardous materials incidents. Usually the local emergency response system (fire department or 911 system)
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will alert a hazardous materials (HAZMAT) team. Table 8.8 provides a checklist for physicians and others involved in hazardous materials incidents.
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TABLE 8.8 Checklist for Physicians and Others Involved in Hazardous Materials Incidents |
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Environmental and Bioterrorism
Recent events, including those of September 11, 2001 and the anthrax attacks later that year, make it clear that the medical profession must be prepared to respond to intentional disasters, including biologic, chemical, and radiologic terrorist attacks. Response by the medical profession to terrorism events will require early identification of ill or exposed persons, rapid implementation of therapy, application of special infection control considerations, and collaboration or communication with the public health system. Clinicians will also play a critical role in managing postexposure treatment and prophylaxis, and managing the psychological and emotional impact of the event. The challenge will be to differentiate those who are truly exposed from those who are not exposed, but are worried they might be. A working knowledge of the agents most likely to be used in a terrorist event becomes critical. The epidemiologic setting of cases plays a pivotal role in guiding diagnostic tests and treatment.
Epidemiologic clues to intentional terrorist events include the following:
Chemical and radiologic casualties are usually readily recognized because of the nature of the agents involved.
Contacting Public Health Officials
Once a potential outbreak or significant cluster or event has been identified, prompt consultation with public health authorities is critical. Most health departments maintain on-call services and can be reached 24 hours a day. The CDC also maintains a 24-hour Emergency Response Hotline at 770-488-7100. The American College of Physicians (ACP) is also a good source of information (see “clinical information” at http://www.acponline.org; last accessed October 26, 2005).
Bioterrorism
The CDC divides potential biologic agents into categories according to risk. Category A agents are those considered to be of greatest risk, and most of them have been used as weapons in the past. These agents are shown in Table 8.9, along with a summary of distinguishing characteristics, and diagnosis and treatment recommendations.
Agents that are “effective weapons of mass destruction” are easily disseminated or transmitted from person to person, relatively easy and inexpensive to produce, cause mortality or widespread infection, and may result in panic and social disruption.
Chemical and Radiologic Terrorism
Decontamination is the most important first step in patient care in a chemical or radiologic event. For greatest effect, decontamination should begin within 1 to 2 minutes of exposure. Decontamination can be summarized as strip, flush, and run. A patient's contaminated clothing should be removed and appropriately disposed of. The patient should then be flushed with copious amounts of water, saline, or soap and water, including the eyes.
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TABLE 8.9 Summary of Bioterrorism Agents, Key Characteristics, and Treatment |
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Those treating chemical or radiologic exposures must not become victims themselves. Under no circumstances should contaminated patients be brought into regular patient treatment areas such as emergency departments or hospitals prior to decontamination. Chemical agents that are most likely to be used in an attack can be classified according to mechanism of action. Table 8.10 summarizes these agents, including a sketch of their characteristics and treatment modalities.
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TABLE 8.10 Recognizing and Treating Poisoning by Chemical Agents |
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When a radioactive weapon is used in an attack, ionizing radiation presents the highest threat to health beyond the initial blast. Ionizing radiation can be alpha or beta particles, or X or gamma rays. The lowest lethal dose of radiation exposure is approximately 200 rem. With appropriate medical care, the lethal dose increases to about 360 rem.
Proper decontamination and shielding procedures can minimize the effects of external exposure to radioactive agents. Internal exposure, primarily from alpha and beta particles taken into the body by breathing particles in the air, absorption through the skin, or by ingesting in water, soil, or food, must also be addressed. Internal contamination can be treated using chelating or blocking agents. Potassium iodide is a blocking agent; it prevents end-organ uptake of radioactive iodine. Chelating agents bind metals into complexes, preventing tissue uptake and promoting urinary excretion. Calcium disodium edetate and penicillamine are used to treat radioactive lead poisoning. Pentetate calcium trisodium (CaDTPA) and pentetate zinc trisodium (ZnDTPA) are used for americium, curium, and plutonium poisoning.
The Larger Emergency Response Picture
As part of the overall Federal National Response Plan (NRP), public health officials and the medical community have the primary responsibility to prepare for and respond to bioterrorism events. This responsibility is included under emergency support function (ESF) number 8 in the NRP. Each hospital is now required to maintain a current Emergency Operations Plan (EOP) that details how the institution will operate in emergency situations.
National syndromic surveillance projects collect emergency department visit data on cases with descriptor “syndromes” that might indicate a terrorist event. Additionally, over-the-counter sales data is collected to monitor medication use for syndromes associated with bioterrorism agents.
The Strategic National Stockpile (SNS) is a national repository of antibiotics, vaccines, and emergency medical equipment maintained by the CDC. The SNS is designed for delivery within 12 hours to any location in the United States. Current plans call for local responders to “go it alone” for the initial 72 hours after an event. Pre-event planning becomes critical to effectively respond to future emergency situations.
Specific References
For annotated General References and resources related to this chapter, visit http://www.hopkinsbayview.org/PAMreferences.