Environmental Medicine: Integrating a Missing Element into Medical Education (1995)

A specific course in environmental medicine may be useful but is not necessary to achieve the competency-based learning objectives described in this report. These objectives can be achieved by integrating an enhancement of environmental medicine into existing disciplines, courses, and clerkships or clinical rotations. In an effort to illustrate this integrative approach, this appendix provides brief examples of how courses and clerkships/clinical rotations can be used as access points for introducing or emphasizing the environmental medicine competencies outlined in the report. These courses and clerkships/clinical rotations (e.g., pharmacology, pathology, pulmonology, hematology, pediatrics, obstetrics/gynecology) are common to all medical curricula regardless of how the curricula are constructed and delivered (e.g., whether they are problem-based or traditional).

The courses are presented first, followed by clerkships/clinical rotations, and both are presented alphabetically as follows, with their page numbers.

COURSES

CLERKSHIPS/CLINICAL ROTATIONS

For each of the courses and clerkships presented below, we briefly discuss the relationship of environmental factors to the discipline and list relevant case studies from Appendix C that can be used for teaching and learning purposes (Index 2 of Appendix C lists specific case studies according to courses and clerkships). These lists are not meant to be all-inclusive, and creative teachers and students may find additional applications. Using these case studies should help to impart knowledge about environmental medicine along with that of the individual, specific discipline. [Note: Indexes in Appendix C facilitate the use of the case studies by presenting them according to (1) agent and condition, (2) courses and clerkships, (3) sentinel pathophysiological conditions for environmental and occupational evaluation, and (4) clinical signs, symptoms, and presenting complaints.]

Instruction in the basic sciences during the first year in medical school includes diverse courses encompassing a variety of the biological sciences. Several of these disciplines include the basic sciences that form the backbone of environmental medicine. Among these are biochemistry, genetics, pharmacology, pathology, and neuroscience. This appendix contains examples for use in teaching aspects of environmental medicine within many of these courses, with the intention of demonstrating that this curriculum content can and should become an integral component of these courses. This integration of examples of environmental medicine into core courses in the preclinical years may also facilitate more effective teaching of the sciences, since applied examples often motivate students, stimulate discussion, and enhance overall comprehension of the discipline.

Courses in biochemistry and physiology could include examples drawn from environmental medicine. In these courses, the use of examples of exposure-induced perturbations of normal function often will serve to inject medical relevance, motivating students in their approach to the subject. When the examples are directly relevant to the material at hand, they reinforce the material and stress its importance.

Selected Case Studies From Appendix C

Courses in community medicine and public health introduce students to the major causes of morbidity and mortality, the distribution of disease in populations, community and population-based approaches for protecting and promoting public health, and the organization and delivery of services and programs to address broad public health problems. Given that the environment has always occupied a prominent place in the public health model of disease, these courses provide an ideal venue for teaching and learning about the impact of environmental factors on health and disease. For example, these courses provide opportunities for students to learn about the impact of pollution and hazardous waste on human health; environmental and occupational hazards affecting particular populations (e.g., children, medical students in their own “work” environment); community-based resources for addressing occupational and environmental health risks, questions, and concerns; and methods for preventing and controlling environmentally-related illness and injury.

Selected Case Studies From Appendix C

Epidemiology and biostatistics are the core disciplines necessary for clinicians to develop an understanding of environmental disease. These courses contain the central scientific framework that distinguishes the population-based approach of environmental and occupational medicine and other public health disciplines from much of clinical medicine. Especially important for environmental and occupational medicine are the approaches used to measure or estimate exposure to potential harmful agents. For students, epidemic outbreaks provide an exciting venue for learning both the basic science of epidemiology and biostatistics and for raising their awareness of the importance of public health. This is an excellent context for introducing statistical concepts (e.g., power of the test), measures of risk (e.g., odds ratios, relative risk, and attributable risk), and sources of bias (e.g., selection, measurement, confounding, and the healthy worker effect). Among the compelling outbreaks are asthma epidemics related to unloading of grain in the ports of New Orleans and Barcelona and carbamate pesticide poisoning due to contaminated watermelons in California. Finally, these courses provide an appropriate setting for addressing the translation of population studies into individual risk estimation for patients.

Selected Case Studies From Appendix C

Although there has been extensive interest in the relationship between environmental and hereditary factors in genetics, this relationship has not been sufficiently clarified to recommend its use in existing courses. While the literature does now include many putative examples of gene-environment interactions pertinent to medicine, they remain speculative enough that their inclusion in a course should be elective, perhaps complementing discussions of the Human Genome initiative and its medical relevance for practicing physicians.

Selected Case Studies From Appendix C

The introduction to clinical medicine (ICM) course is commonly taught in the first years of medical school and may run across semesters. Although it does not necessarily provide students with their first patient contact, it remains the traditional locus for teaching the theory and especially the practice of taking a complete medical history and performing a physical exam. Typically, students are assigned to interview and examine

6 to 12 patients, write up these encounters in a fairly standard format (e.g., chief complaint; history of present illness; past medical history), and turn them in to a preceptor for discussion and critique. The write-ups are long and require that students practice all aspects of history-taking on all patients, rather than focussing only on what appears to be relevant to the patient’s presenting illness. A parallel focus in this type of course usually involves many hours of pathophysiology lectures on the organ systems. The following suggestions are based on this format.

As stated in Chapter 3, history-taking is the key skill for promoting and developing the other competencies in a manner that is integrated with patient care. It is well known that house staff and physicians in private practice generally are not skilled in eliciting an occupational and environmental history from patients. This is not a difficult skill to master, but it does require practice and a sense of territorial familiarity to encourage further practice and skill building. All standard medical texts list “occupation” as part of the “social history,” and some go on to list “toxic exposure” and other details as well. However, we believe that course directors and preceptors typically do not teach students to value this portion of the history, and thus they soon lose interest in it. There is little extrinsic reward for students’ doing a good job on the environmental and occupational history, and little or no consequence for ignoring it. If this perception is acquired in a “leisurely” ICM setting, students will not practice this aspect of history-taking and will not have the competency in their repertoire when they confront the more demanding third-year clerkships. Thus, we propose that an emphasis be placed on environmental/occupational history-taking from the outset in the ICM course.

Students should be explicitly required to perform and write down a detailed environmental/occupational history on all patients they interview, whether or not it is relevant to the presenting illness, just as a detailed family history or sexual history is taken on all of the ICM patients. This should include the current or most recent, usual occupation, with a job description, and a list of any toxic or other exposures experienced (e.g., ergonomic hazards) and protective equipment used. All previous jobs should be listed. Students should be encouraged to ask patients to clarify any unfamiliar terms that come up during the interview. Patients’ homes should be described in terms of their heating system, air conditioning, type of building materials, water supply, and presence of problems with agents such as radon; lead paint; wood, kerosene, or other smoke; unvented appliances; water-damaged carpets or structural materials; proximity to known hazardous waste sites; and pesticide use. Enforcing this requirement needs attention, because most preceptors cannot be expected to give it high priority, as they will not feel completely competent themselves. One solution is to enforce it in a parallel course that has specific responsibility for environmental and occupational issues and make this part of history-taking and the ICM write-up dovetail with its own teaching objectives. Otherwise, specific leadership from the ICM course director will be necessary, with some attention to see that practice occurs. If history-taking patterns are allowed to develop without this skill, environmental/occupational history-taking skills will be

exceedingly hard to retrofit in the future. An important benefit of this component of history-taking is building rapport with patients. Discussion of a patient’s work and home generally helps to improve the physician-patient relationship. Appendix A contains the ATSDR case study on “Taking an Exposure History” and provides an excellent example and source of material for teaching and learning the skill of taking good environmental and occupational histories.

Selected Case Studies

Courses in microbiology use clinical examples to demonstrate either pathophysiologic aspects of illness due to an organism or public health aspects such as reservoirs, vectors, and susceptibility. The listed examples, as well as others, such as TB transmission in hospitals, demonstrates the overlap between environmental investigations and microbiology, sometimes leading to recognition of new pathogens.

Selected Case Studies From Appendix C

Environmental causes of nervous system disease are surprisingly common and the environmental and occupational causes of both peripheral and central nervous system diseases are well described. The agents and exposures responsible for these conditions provide a wealth of opportunities for exploration of the biology, cellular physiology, and anatomy of the central and peripheral nervous systems.

Selected Case Studies From Appendix C

The relationship between environmental hazards and nutrition is intimate but often subtle; courses in nutrition provide an excellent setting to reach environmental health and provide a wealth of relevant examples. Most obviously, food and water provide a major source for environmental contaminants, such as occurred in Minimata Bay in Japan (organic mercurials concentrated in sea fish). Less obviously, choices of diet impact the long-term bioaccumulation of hazardous materials, such as pesticide residues and PCBs. Some environmental toxicants act by competition with micronutrients, such the role of goitragens in blocking iodine uptake and metabolism. Finally, evidence is accumulating that the biological effects of toxicants may be modified by dietary behaviors, such as recent evidence suggesting a chemopreventive effect of various antioxidants.

Selected Case Studies From Appendix C

Pathologists have long realized the importance of environmental disease. The teaching of “environmental pathology” has been standard practice within this discipline for many years, and the major texts in pathology include sections on environmental disease. For a well-known minority of conditions, especially pneumoconioses, pathologic examination can provide both a tissue and an etiologic diagnosis. More commonly, specific etiologic diagnoses will require information from a patient’s medical history to supplement the tissue diagnosis, as in the case of hypersensitivity pneumonitis, toxic neuropathy, hepatotoxicity, and malignancy. Nevertheless, the pathologic features of each of the above-mentioned conditions can often suggest toxic etiologies over other types of pathophysiology, and such cases provide excellent material for clinicopathologic correlation.

Selected Case Studies From Appendix C

The teaching of pharmacology in medical school is primarily targeted at the therapeutic use of pharmaceuticals. The clinician is primarily interested in the use of drugs to prevent and treat human disease, as well as to ameliorate suffering. Therefore, general courses in pharmacology in medical school are aimed at providing a rational basis for the clinical use of therapeutics. At the same time, it is important that the physician be concerned about exposure to chemical agents, such as through environmental pollution and industrial wastes. This is a recognized component of pharmacology but often assumes a secondary role in the education process. We suggest that the teaching of pharmacology in medical schools include, as a central part of the curriculum, examples of the pharmacology of environmental and work-related toxicants, as well as pharmaceutical therapeutics. The general principles of pharmacology are directly applicable to such disease-causing agents, and there are many examples that can be

integrated into the teaching of pharmacology at almost every level. A wide variety of toxicants can serve as examples for teaching about absorption, transformation, and excretion, and the various classes of compounds.

Selected Case Studies From Appendix C

In the clinical or clerkship years of medical school, students receive instruction in several areas, such as pediatrics, psychiatry, and general internal medicine. We discuss these areas below and a few others that are common in most medical curricula. Each area is discussed briefly in terms of the relevance of environmental factors. This is followed by a list of selected case studies from Appendix C that can be used for illustrative purposes in each of the disciplines.

The pathophysiology of the cardiovascular system includes examples of disease caused by environmental agents. Both acute and chronic heart disease have been related to environmental and occupational exposures. However, the precise mechanisms of

toxicity of some of the compounds associated with heart disease are poorly understood.

Selected Case Studies From Appendix C

Any abnormality or inflammation of the skin that is either directly or indirectly attributable to exposures or actions at work constitutes an occupational skin disorder. There is an enormous variety of cutaneous reactions and clinical skin disorders that are related to work and the general environment. In fact, skin disorders are among the most frequently reported environmental and occupational diseases. Patterns of exposure-induced injury can be very specific in some cases or they may present as non-specific inflammatory change. Thus, environmental and occupational causes of all types of dermatologic disorders should be considered in the teaching of the differential diagnoses of skin disease.

Selected Case Studies From Appendix C

Emergency physicians are typically confronted with acutely ill individuals, and their primary focus must be on the stabilization of vital signs. However, people exposed to some environmental asphyxiants such as cyanide, pesticides, and carbon monoxide benefit from specific therapy and need to be correctly diagnosed at the outset. Inhalation injury to the respiratory tract requires a consideration of immediate management, such as whether to hospitalize individuals for observation of delayed pulmonary edema, as well as an appreciation of delayed consequences of exposure, such as reactive airways dysfunction syndrome (RADS). Consideration needs to be given to treatment of standard smoke inhalation as well as to agents that cause delayed pulmonary edema or bronchiolitis (phosgene, nitrogen dioxide). A consideration of RADS as a late outcome of irritant inhalation is also pertinent.

Selected Case Studies From Appendix C

Environmental toxicants uncommonly cause major endocrine disturbances, except in the setting of overwhelming (accidental) exposures, such as to the biocide Vacor, a cause of acquired diabetes. More commonly, however, environmental factors may complicate endocrine alterations, or interact with them. A current area of exciting inquiry is the possibility that many carcinogenic agents, such as pesticides, may act via steroid receptors, such as the estrogen receptor in breast tissue.

Selected Case Studies From Appendix C

Many of the clinical concerns in the family medicine curriculum can be found in this appendix under specific disciplines such as pediatrics, internal medicine, and obstetrics. Here we suggest a focus on the household environment, including contaminants introduced by parents’ work, hobbies, pets, and personal habits. Clinical problems that emphasize the shared home environment are best taught where all family members are covered by the same health care provider.

Selected Case Studies From Appendix C

Exposure-induced hepatotoxins are well known. Any course on gastroenterology includes a significant amount of time devoted to the study of liver dysfunction. Many causes of liver dysfunction are presented and studied in depth. Often, such discussions are aimed at the clinical consequences of hepatic insufficiency as a result of pharmaceuticals; alternatively, the use of pharmaceuticals in patients with liver dysfunction can also be discussed. We urge that courses include a discussion of environmental sources of hepatotoxic compounds including alcohol and other hepatotoxins such as polychlorinated biphenyls (PCBs), vinyl chloride, and chromium.

Selected Case Studies From Appendix C

Courses in hematology routinely include study of the biochemistry and function of the erythrocyte. As part of this, heme synthesis and the protoporphyrin pathway are addressed in detail. In addition, causes of anemia are addressed, including the forms attributable to environmental and occupational exposures. Therefore, many of these exposures can be introduced easily into the teaching of hematology and oncology.

Selected Case Studies From Appendix C

Instruction in infectious disease provides many rich examples of the application of epidemiology in medicine. Epidemic evaluation includes many cases where attention is focused upon illnesses that are environmental in the broadest sense. The principles of

evaluation of clusters of infectious disease are also instructive for other applications, including disease caused by workplace exposures and other environmental agents.

Selected Case Studies From Appendix C

An internal medicine clerkship is an excellent opportunity to refine pathophysiologic knowledge and is especially useful for developing clinical skills critical to environmental/occupational medicine. Students must develop clinical judgment about when to pursue environmental/occupational etiologies. We suggest an approach of triage, where it is recognized that some pathophysiologic entities are more likely to have underlying environmental/occupational etiologies than others. For these conditions or complaints, environmental/occupational causes should always be carefully considered and should be included in the development of a differential diagnosis and consideration of pertinent negatives during oral presentations.

Selected Case Studies From Appendix C

Kidney pathology is complex and includes many aspects of basic sciences in discussing glomerular filtration and iron transport. Specific patterns of renal injury are associated with many toxicants and pharmaceuticals.

Selected Case Studies From Appendix C

The neurologic approach, much like the internal medicine approach, focuses on the etiologic evaluation of certain complaints and pathophysiologic states.

Selected Case Studies From Appendix C

Most commonly students will need to respond to patient concerns about the potential implications of an environmental or occupational exposure to a pregnancy or a desired pregnancy. Counseling and data gathering are more germane than diagnosis in this context. There is a defined, and likely incomplete, list of environmental and occupational agents with reproductive and developmental effects.

Selected Case Studies From Appendix C

Any organ-systems course that discusses the physiology of musculoskeletal injury should also address rapid alternating movement as a source of morbidity. Vibration-induced disease as a cause of musculoskeletal injury is well studied and well understood. Ergonomics is a discipline that should be familiar to most physicians. Students would do well to learn the principles of ergonomics since back pain and other musculoskeletal conditions will form a significant portion of any adult primary-care practice.

Selected Case Studies From Appendix C

The teaching of otolaryngology should obviously address noise-induced hearing loss. This preventable cause of significant morbidity is underdiagnosed and underrecognized by physicians in general. Thus, it would serve physicians well to highlight the many problems caused by chronic exposure to excessive noise. The pathophysiology and clinical consequences of such exposures are well documented, including the presentation and diagnosis of this condition. Any discussion of noise-induced hearing loss should stress the principles of prevention. Thus, source reduction and history-taking skills should be reinforced in any otolaryngology course. In addition, the upper respiratory tract is frequently the target of environmental and occupational irritants and allergens.

Selected Case Studies From Appendix C

Evidence of the profound impact of home environmental factors such as tobacco smoke, lead paint, and poisons on the health of children continues to accumulate. For example, children that experience developmental delay or poor school performance often live in homes and communities with high levels of lead exposure. Their smaller size, developing organ systems, higher respiratory rates, and differing metabolism rates make children particularly susceptible to some agents, including pesticides. In addition, recurrent upper or lower respiratory symptoms in children may signify recurrent or chronic exposure to allergens or irritants such as environmental tobacco smoke, nitrogen oxides from gas stoves, combustion products from inadequately vented wood stoves or space heaters, or agents resulting from home renovation projects.

Selected Case Studies From Appendix C

Current courses in pulmonary medicine usually include a discussion of many environmental and occupational diseases. This is natural since the lung is the portal of entry for all airborne toxicants. Among the competencies that we describe in this report is the knowledge of signs, symptoms, and exposure sources for many agents that produce pulmonary pathology. These include asbestos and agents that cause hypersensitivity pneumonitis. Further, environmental causes of asthma are well-studied, and any discussion of it in a pulmonary medicine course should include a detailed look at the exposure-induced nature of reversible airways disease. Exposure to respiratory irritants is a well-known cause of asthma, and the prevalence of asthma in the general population is increasing. Therefore, using examples of known environmental and occupational causes of the pulmonary disease could serve to make future clinicians more aware of these agents.

Selected Case Studies From Appendix C

Because of the unusual opportunity for sustained student-patient discussion that occurs on many psychiatry rotations, this clerkship presents a unique opportunity for students to explore the relationship of an individual’s work and working conditions to his or her health and happiness. In doing so, students will learn to allow patients to explain aspects of their life, their work, and their home environment—subjects about which they are more expert than the physician. This skill can have ramifications far beyond psychiatry as a discipline, and can reinforce patient-centered holistic approaches to care.

Selected Case Studies From Appendix C

The lung is the portal of entry for many occupational and environmental toxicants that may affect the lung directly. Various radiographic patterns may be pathognomonic or highly suggestive of specific exposures, while other patterns should at least raise the possibility of an environmental exposure. A clinical radiology rotation is ideal for suggesting differential diagnostic possibilities that include toxic exposure.

Selected Case Studies From Appendix C