Robert J. Harrison, MD, MPH
Karen B. Mulloy, DO, MSCH
The relationship between exposures at work and the development of diseases has been well documented throughout history. One of the earliest writings on lung conditions of miners was in the fourth century BC by Hippocrates. With the publishing of De Morbis Artificium (Diseases of Workers) by Bernardino Ramazzini in 1700, the description of the health hazards of chemicals, dust, metals, and other agents encountered by workers in 52 occupations established occupational exposure as an important contributor to chronic disease. Ramazzini proposed that physicians should extend the list of questions that Hippocrates recommended they ask their patients by adding, “What is your occupation?”
The importance of the occupational and environmental medical history cannot be overemphasized. Work affects the health of all people, whether by injury or through its effects on acute and chronic illnesses. Moreover, with the advent of industrialization and the introduction of thousands of chemicals and other toxic substances into the environment, it is important for the medical practitioner to consider both occupational and environmental exposures when taking the medical history.
Screening History
The relationship of injury or illness to work is often overlooked or even forgotten in the medical history. An accurate and complete occupational and environmental history is the most important tool in the evaluation and diagnosis of occupational and environmental injuries and illnesses. The patient who presents with wheezing may have asthma related to a long history of seasonal allergies, or the asthma may be related to exposure to isocyanates on the job. Without the occupational and environmental history, the correct diagnosis, treatment plan, and prevention may not be achieved.
Accurately diagnosing occupational illnesses is important beyond the usual reasons for accuracy in medical diagnosis. There are public health, social, and economic implications of occupational disease and injury for the community of workers in the same workplace or in other workplaces with similar exposures. In many states, the diagnosis of an occupational illness triggers additional responsibility on the part of the clinician. These responsibilities are primarily those of timely notification: informing the worker regarding the potential legal and other implications of the diagnosis, informing the workers’ compensation insurer of the diagnosis and the basis for the clinician’s opinion, and reporting to the appropriate public health or labor-related governmental agencies. A differential diagnosis that appropriately includes occupational exposures as potential causes or exacerbating factors of the patient’s presenting symptoms or suspected disease is a crucial first step in recognition (Figure 4–1).
Figure 4–1. The initial clinical approach to the recognition of illness caused by occupational exposure.
With the passage of the 2009 Health Information Technology for Economic and Clinical Health (HITECH) Act, there has been an increase in the development and use of electronic health records (EHRs) within clinical practice. The EHR offers the ability for the clinician to have immediate access to a wide variety of significant information about their patients. The EHR allows for the capture of occupation and industry that will aid not only in the diagnosis of individual patients, but will also improve health and safety conditions for groups of workers and expand public health surveillance of occupational illness and injury for prevention (see Chapter 5).
The chief complaint and history of present illness may suggest potential diagnostic possibilities that lead to specific etiologic hypotheses. For example, a history of headache while at work suggests potential solvent or carbon monoxide exposure, and cough and wheezing while at work or predictably delayed after leaving work may suggest irritant or triggering allergen exposure. A history of fevers and back pain in a clinical laboratory worker or slaughterhouse worker suggests possible brucellosis. Additional sources of information may help to confirm or rule out hypothesized occupational or environmental etiology.
EXPANDED HISTORY
If answers to the occupational/environmental survey questions are positive, a more detailed follow-up questioning is necessary (Table 4–1). It is also important to collect information about current and previous jobs in a systematic manner and inquire about possible environmental exposures at home and in the surrounding community and hobbies. The Agency for Toxic Substances and Disease Registry (ATSDR), a federal public health agency of the U.S. Department of Health and Human Services, provides health information to prevent harmful exposures and diseases related to toxic substances. In the ATSDR “Case Studies in Environmental Medicine” (http://www.atsdr.cdc.gov/csem/csem.html), there is a case study of “Taking an Exposure History” that has an expanded “Exposure History Form” that may be used to capture an expanded and detailed occupational and environmental history.
Table 4–1. Essential elements of the comprehensive occupational history and questionnaire.
Prior Medical History
It is important to have access to the patient’s entire medical history. Have the employee sign a release to obtain medical records from the treating or consulting clinicians. These records may provide important clues about prior diagnoses, history of exposures, predisposing factors for illness, and the course and progress of the illness.
Exposure Assessment
When a patient’s medical history suggests that occupational or environmental factors may be a primary or secondary cause or contributor to illness, the clinician should identify all potentially toxic materials or hazards in the workplace, home, and/or environment.
Useful employee documents may include medical surveillance and/or job surveillance records from the employer. The employer or union may have reports from a safety inspection or an industrial hygienist that may provide insight into the exposures and risk for disease. The company health and safety manager should cooperate in answering questions about similar illnesses in coworkers. Working with the patient and obtaining permission to talk to the employer/union representative is an important step in the medical workup. Conducting a worksite evaluation will be invaluable into gaining insight into possible work exposures or work processes that the patient had not thought important but that may be contributing to the medical illness.
The clinician can best understand the potential contribution of workplace exposures to the patient’s illness by visiting the workplace, although time constraints may limit the number of patients for whom this may be performed. This necessitates first obtaining the permission of the patient to contact the workplace and then obtaining access to the workplace by contacting the employer’s health and safety manager or, for smaller workplaces, the owner/manager. The patient also may provide the name of a union shop steward or health and safety committee member who may be of assistance in obtaining access to unionized work sites.
Information that may be obtained during a site visit includes a detailed description of the work processes, prior results of industrial hygiene sampling and medical surveillance, lists of toxic or hazardous materials used, and, most important, a guided tour of the work site with a focus on the specific work areas where the patient has been working. If the worker is employed by a large company with an organized health and safety program, discussion with an industrial hygienist on the company staff or, if unionized, at the international union may be useful for identifying other exposure information, control measures, and potential future monitoring to evaluate the effectiveness of control measures.
There may have also been an inspection performed by Occupational Safety and Health Administration (OSHA) or other safety and health regulatory agencies that can be accessed. An OSHA referral may be particularly useful in situations where the clinician suspects that potential violations of OSHA standards may be occurring. Additionally, the National Institute for Occupational Safety and Health (NIOSH) has a Health Hazard Evaluation (HHE) program that can perform public health investigations that may provide additional information. The HHE is a study of a workplace to determine if workers are exposed to hazardous materials or harmful conditions.
Obtaining the assistance of a physical therapist, occupational therapist, or hand therapist experienced with workstation evaluation may be useful with ergonomic problems and repetitive-motion injuries in the workplace.
The most readily available source of information on chemical ingredients in compounds available commercially is the safety data sheet (SDS), previously called a material safety data sheet (MSDS). The SDS is a document that provides information on the properties of hazardous chemicals and how they affect health and safety in the workplace. The OSHA Hazard Communication Standard (HCS) requires chemical manufacturers, distributors, or importers to provide workers access to the SDS on all hazardous substances in a workplace.
There are other agencies and organizations that may help in the evaluation of a patient for both occupational and environmental exposures. The American Association of Poison Control Centers offer free and confidential medical advice 24 hours a day, 7 days a week and are a resource for advice on toxicological issues. The ATSDR has information on exposures and diseases related to toxic substances. There are also datasets readily available to research into specific exposures and chemicals.
Sentinel Case Reporting
NIOSH defines the sentinel health event (occupational) (SHE[O])as “a disease, disability, or untimely death, which is occupationally related and whose occurrence may provide the impetus for epidemiologic or industrial hygiene studies; or serve as a warning signal that materials substitution, engineering control, personal protection, or medical care may be required.” The SHE(O) sentinel cases can prove to be extremely useful in triggering regulatory or public health investigations that can lead to prompt control of new hazards, thereby preventing new cases of work-related disease from occurring. Each state has specific reporting requirements for suspected occupational injuries and diseases.
ENVIRONMENTAL HEALTH HISTORY
Pollution of air and water, contamination of food, releases from nearby industrial facilities or waste sites, and environmental hazards in the home environment are all common causes for concern among patients, community members, and public health officials. Physicians today are called on increasingly to address questions or problems related to environmental health. The environmental health history is becoming an important tool for evaluating patients, especially on initial clinician visits and for those with new-onset asthma or allergic rhinitis symptoms, dermatitis, symptoms suggesting potential lead or pesticide poisoning or exposure, as well as at least once during prenatal and well-baby visits. The CH2OPD2 mnemonic (community, home, hobbies, occupation, personal habits, diet, and drugs) may be a useful starting point for a more focused environmental history. All physicians must understand the effects of common environmental exposures and the similarities and differences between environmental health and occupational health.
ESTABLISHING CAUSATION
When presented with a patient with a constellation of symptoms and possible exposures, it may not be clear if the condition is work or environment related. Once there is a working diagnosis and the research into the exposures has been completed, the clinician needs to consider the following aspects:
Strength. How strong is the association between the suspected risk factor and the observed outcome?
Consistency. Does the association hold in different setting and among different groups?
Specificity. How closely are the specific exposure factor and the specific health outcome associated?
Temporality. Does the cause antedate the effect?
Biologic gradient. Does a dose-response relationship exist between the exposure and the health outcome?
Plausibility. Is the apparent association consistent with what is known of the natural history and biology of the disease?
Coherence. Is there no conflict in the cause and effect interpretation and what is known on the natural history and biology of the disease?
Experimental evidence. Does the experimental evidence support the hypothesis of an association?
By answering these questions, it will help in the thought process and the deliberation of whether a specific case is work related, environment related, or neither.
A CASE PRESENTATION
A 42-year-old woman comes to your clinic for her annual physical examination. She has no major medical illnesses, takes a multivitamin and calcium, and her only complaint is some mild fatigue in the last several months. Her laboratory tests were normal except for a mild anemia. Follow-up testing does not reveal a cause for the anemia. The patient states she wonders if the anemia is related to her work at an electronics assembly plant. You inquire about what she does at work and she tells you that her job is soldering conductive wires to printed circuit boards. You obtain permission from the patient to talk to the company safety professional. The safety professional states that her exposures might include lead exposure and that he will request an industrial hygiene (IH) evaluation to see if the safety measures that have kept the patient free of lead exposure in the past are still working. In addition, the workers’ compensation insurance company contacts you to discuss the case. You have received permission from the patient to talk with the safety personnel at the workers’ compensation insurance company.
Following your discussion with the company safety professional, you have tested the patient for blood lead level and it comes back slightly elevated. It is your responsibility to notify the state Department of Health as a part of their lead poisoning prevention program. They inquire about your patient’s employer, and if there are any children involved. The state has an occupational health surveillance program and they will be contacting the company to see if the lead exposure is from the worksite and if other workers are involved.
You discover in the course of taking both occupational and environmental histories that the patient has a hobby of making stained glass windows. Your questions reveal that this is done in her basement without adequate ventilation. A private IH survey reveals lead deposits in the basement with wipe samples. The patient does not have any children in the house but her husband is being tested for lead exposure.
The IH report from the workplace showed an area in her work station that needed further engineering controls but that no other workers had elevated blood lead levels. The patient is instructed on proper IH measures in the home and once the home environment is cleaned she is allowed to return to her hobby with proper attention to safe practices when handling lead.
RESOURCES
Agency for Toxic Substances and Disease Registry (ATSDR). www.atsdr.cdc.gov/.
Medical Management Guidelines (MMGs) for Acute Chemical Exposures. www.atsdr.cdc.gov/MMG/index.asp.
Toxicological Profiles. http://www.atsdr.cdc.gov/toxprofiles/index.asp.
American Association of Poison Control Centers (AAPCC). http://www.aapcc.org/.
Environmental Protection Agency (EPA) has numerous resources and datasets on environmental issues with specific information on state and local communities. www.epa.gov/.
EPA Integrated Risk Information System (IRIS) is an electronic database containing information on health effects of many substances. http://cfpub.epa.gov/ncea/iris/index.cfm.
National Institute for Occupational Safety and Health (NIOSH). www.cdc.gov/niosh/.
NIOSH Registry of Toxic Effects of Chemical Substances. www.cdc.gov/niosh/rtecs.
NIOSH Occupational Sentinel Health Events. http://www.cdc.gov/niosh/topics/SHEO/.
Occupational Safety and Health Administration (OSHA). www.osha.gov/.
State health departments have divisions of occupational and/or environmental health and have a wide variety of resources. The New Jersey State Health Department maintains a catalog of chemical fact sheets (www.state.nj.us/health/eoh/rtkweb/rtkhsfs.htm) and California State Department of Health Services’ Hazard Evaluation System and Information Service (HESIS) has a series of chemical and ergonomic fact sheets for workers and clinicians (www.dhs.ca.gov/ohb/HESIS/). The California Office of Environmental Health Hazard Assessment (OEHHA) at www.oehha.ca.gov/ is a resource with a focus on the toxicology of environmental chemicals.
US National Library of Medicine: Toxicology Data Network (Toxnet). http://toxnet.nlm.nih.gov.
Chemical Information Specialized Information Services. http://sis.nlm.nih.gov/chemical.html.
ChemIDplus: Chemical Dictionary Database. http://chem.sis.nlm.nih.gov/chemidplus/.
National Report on Human Exposure to Environmental Chemicals. www.cdc.gov/exposurereport/.
Many unions in the United States have occupational safety and health divisions that may help in evaluation of worksites, health and safety education of groups of workers, and provide for worker protection. http://www.aflcio.org/.
Workers’ compensation insurance carriers may employ occupational health professionals familiar with the problems at a particular worksite.
REFERENCES
Cegolon L: The primary care practitioner and the diagnosis of occupational diseases. BMC Public Health 2010;10:405 [PMID: 20618928].
Liebman AK: To ask or not to ask: the critical role of the primary care provider in screening for occupational injuries and exposures. J Public Health Manag Pract 2009;15:173 [PMID: 19202419].
Luckhaupt SE: Documenting occupational history: the value to patients, payers, and researchers. J AHIMA 2011;82:34 [PMID: 21848097].
Newcomb RD: Is an occupational examination superior to an occupational health history alone for preplacement screening in health care settings? J Occup Environ Med 2012;54:276 [PMID: 22361991].
NIOSH. Occupational Sentinel Health Events. http://www.cdc.gov/niosh/topics/SHEO/.
Taiwo OA: Recognizing occupational illnesses and injuries. Am Fam Physician 2010;82:169 [PMID: 20642271].
Verbeek J. When work is related to disease, what establishes evidence for a causal relation? Saf Health Work 2012;3:110 [PMID: 22993715].
Woodall HE: Screening questionnaire for work-related health problems. Am Fam Physician 2011;83:1247 [PMID:21661704].
SELF-ASSESSMENT QUESTIONS
Select the one correct answer to each question.
Question 1: Occupational/environmental history
a. should include information about current and previous jobs in a systematic manner
b. need not include possible environmental exposures at home and in the surrounding community and hobbies
c. must establish a pattern of symptoms or organ system involved
d. may ignore an exposure type, occupation, or industry
Question 2: Safety data sheets
a. must be available to workers if represented by counsel
b. provide information on the properties of hazardous chemicals and how they affect health and safety in the workplace
c. are required by OSHA to be up-to-date, complete, and accurate
d. discourage contact with a manufacturing company toxicologist
Question 3: Sentinel Health Event (Occupational) (SHE[O])
a. is a disease, disability, or untimely death, which is legally established as caused by work
b. must be substantiated by epidemiologic or industrial hygiene studies
c. requires materials substitution, engineering control, personal protection, or medical care
d. may trigger regulatory or public health investigations that can lead to prompt control of new hazards