Version May 2024
INTRODUCTION — An overview of occupational and environmental health is found here.
Occupational lung disease is discussed in detail separately, as are adult lead poisoning, arsenic toxicity, female reproductive toxicity, chemical and biological terrorism, and concerns related to obstructive sleep apnea and vehicle accidents among commercial vehicle drivers.
●(See "Occupational asthma: Definitions, epidemiology, causes, and risk factors".)
●(See "Lead exposure, toxicity, and poisoning in adults".)
●(See "Arsenic exposure and chronic poisoning".)
●(See "Overview of occupational and environmental risks to reproduction in females".)
●(See "Chemical terrorism: Rapid recognition and initial medical management".)
●(See "Identifying and managing casualties of biological terrorism".)
●(See "Drowsy driving: Risks, evaluation, and management".)
●(See "Clinical presentation and diagnosis of obstructive sleep apnea in adults".)
ROLES OF THE CLINICIAN — Environmental and occupational issues present both diagnostic and preventive care opportunities in primary care practice, emergency medicine, pediatrics, and various medical specialties. Practitioners should be knowledgeable about environmental and occupational health risks, particularly among vulnerable populations, especially given the increased exposures and hazards related to climate change [1,2].
Clinicians need to know how to take a good environmental/occupational history and should have a reasonable understanding of common environmentally related illnesses and injuries as well as basics of exposure assessment (algorithm 1) [3]. A patient's symptoms may be caused or exacerbated by work, other environmental exposures, and climate change. A non-occupationally related illness, disease, or injury may require assessment of ability to perform job duties or the need for short- or long-term duty restrictions or accommodations. Work-related injuries or illnesses may require assessment of impairment, disability, and eligibility for workers' compensation. In addition, identification of potential risks from work, environment, or climate (such as increased heat) can also lead to guidance related to important protective and preventive actions [4].
Concerns about potential chemical or biological terrorism, as well as the occurrence of industrial disasters, have made it imperative that clinicians immediately recognize patterns associated with exposures to key chemical agents (such as cyanide and nerve agents) and biological agents (such as anthrax) [5,6]. Clinicians and health centers should have sufficient background to respond to exposures from accidental contaminations of drinking water or air, from technologies such as hydraulic fracturing (fracking), from chronic contamination of water with "forever chemicals" such as the per-and polyfluoroalkyl substances (PFAS) [7], and from natural disasters (such as flooding, hurricanes, wildfires) [8]. In addition, health providers must be aware of the risks to essential workers and first responders, as during the coronavirus disease 2019 (COVID-19) pandemic [9,10] and in anticipation of future infectious disease outbreaks. (See "Chemical terrorism: Rapid recognition and initial medical management" and "Identifying and managing casualties of biological terrorism" and "COVID-19: General approach to infection prevention in the health care setting".)
Clinicians also have an opportunity for preventive care related to occupational and environmental exposures. A patient's reported exposures and living conditions may prompt important interventions to prevent future illnesses or injuries for the patient and for others, for example by preventing occupational illness in other employees at the work site or addressing climate change-related environmental issues and potential health risks [1,11-13]. One important example is identifying workers with outdoor jobs with heat exposures (such as roofers) and educating them about symptoms and prevention of heat stress [4].
EPIDEMIOLOGY
Occupational injury and illness — The full extent of occupational injuries and illness is difficult to measure due to underreporting. In 2019, the US Bureau of Labor Statistics (BLS) reported the 2018 results from employer surveys and reports: 5250 fatal work-related accidents (3.5 per 100,000), a 2 percent increase from 2017 [14], and 2.8 million nonfatal injuries and illnesses [15]. Nearly one-third of reported cases necessitated days away from work, job transfer, or restricted duties at work.
Although work-related illnesses and injuries may be easily identified by known precipitants, some may only become apparent after a prolonged period of exposure. Examples of illnesses related to occupational exposures include asthma and other lung diseases, cardiovascular disease, heat-related conditions, infectious diseases, and cancers.
●Asthma related to work can be caused or exacerbated (work-exacerbated asthma [WEA]) by a workplace sensitizer or irritant [16,17]. WEA has been reported to occur in 21.5 percent of people with asthma who work [18]. Guidelines are available to assist clinicians with diagnosing, managing, and preventing occupational asthma [16,18]. Occupational asthma is discussed in detail elsewhere. (See "Occupational asthma: Definitions, epidemiology, causes, and risk factors".)
●Epidemiologic studies of first responders to the World Trade Center disaster in the United States in September 2001 have identified associations with decreased pulmonary function as well as an increased incidence of sarcoid-like granulomatous pulmonary disease and different cancers, including thyroid and prostate carcinomas and multiple myeloma [19-23]. Our understanding of the long-term effects, as well as clinical management guidelines, continues to evolve [24]. (See "Irritant-induced asthma", section on 'Causes and risk factors' and "Pathology and pathogenesis of sarcoidosis", section on 'Occupational and environmental exposures'.)
●Among firefighters, studies have demonstrated an increase in cardiovascular events when engaged in fire suppression as well as during other activities [25,26]. Data from physiological, epidemiologic, and clinical studies have led to recommendations for preventive measures for firefighters, including banning smoking and tobacco products, implementing wellness programs that promote exercise and healthy diets, performing annual medical evaluations, and considering retirement from active firefighting at age 60 [26].
●Nanotechnology, which involves the production of materials in near atomic size (1 to 100 nm) [27,28], raises health concerns for industry workers. Nanosized materials exhibit unique properties that affect physical, chemical, and biological behavior, and preliminary research suggests that breathing certain types of nanomaterials may affect the respiratory system [29]. There are efforts to create registries, approaches to medical surveillance, and numerous guidelines for exposure protection and handling nanomaterials [29].
●Heat-related illnesses are becoming more common due to a global increase in average temperatures, with some population areas experiencing prolonged periods of higher temperatures as well as increased frequency and intensity of extreme heat events [4]. In the last two decades, there has been a 54 percent increase in heat-related mortality among people older than 65 years [4]. Clinicians need to recognize symptoms of both mild and severe heat-related illnesses and identify those individuals with increased risks and susceptibility, such as those with "heat-sensitive" illnesses, people working or exercising in hot environments, and people living in conditions that create heat hazards (urban heat islands or living quarters on upper floors of unairconditioned buildings). Clinicians should make inquiries regarding job tasks and living environments and provide relevant guidance if heat-related risks are identified. Adding a question to the interview such as "Do you have a way to stay cool on hot days?" could be helpful.
Air pollution — Burning fossil fuels generates a variety of pollutants, including ground-level ozone, particulate matter, carbon monoxide, and sulfur dioxide, as well as greenhouse gases. This resultant air pollution is a significant contributor to illness and increased mortality rates and can be measured by the air quality index (AQI). The AQI quantifies five air pollutants [30], including:
●Ground level ozone
●Particulate matter (PM; of aerodynamic diameters 10 microns or less [PM10] and very fine particles with aerodynamic diameter of 2.5 microns or less [PM2.5])
●Carbon monoxide
●Sulfur dioxide
●Nitrogen dioxide
The AQI scale runs from 0 to 500, with a value of 100 or less corresponding to the national air quality standard (AQI of 0 to 50 is consistent with good air quality; AQI of 51 to 100 is consistent with moderate air quality). An AQI of greater than 100 is considered unhealthy for sensitive groups (ie, those with baseline lung disease), and a value greater than 300 signifies hazardous conditions.
During wildfires in September 2020 in the United States, AQIs were in the hazardous range, with some parts of California, Washington State, and Oregon having AQIs in the 300s to 400s.
Real-time AQIs are available at the following sites:
Health care providers can consult these and other resources when advising at-risk patients, such as those with asthma, chronic lung disease, cardiovascular disease, or COVID-19 on actions to take during "bad air" days [31].
Varying air pollution levels have been linked to variable rates of morbidity and mortality [32-40]. In adults, higher air pollution levels are associated with increased cardiovascular and respiratory illnesses, as well as breast cancer [32,33,35-37,41-48]. As an example, in a 2012 meta-analysis, short-term exposure to a variety of air pollutants (carbon monoxide, nitrogen dioxide, and sulfur dioxide) was associated with an increased risk of myocardial infarction; the population attributable risk was estimated as 0.6 to 4.5 percent [36]. The effect of air pollution on cardiovascular disease risk is discussed elsewhere. (See "Overview of possible risk factors for cardiovascular disease", section on 'Air pollution'.)
Further, a 2023 meta-analysis of 16 studies suggests that exposure to particulate matter <2.5 microns in diameter (PM2.5) is associated with increased risk of dementia [49].
According to the World Health Organization, outdoor air pollution caused an excess of 4.2 million deaths globally in 2016 [50]. Studies have consistently shown an association between elevated ambient levels of fine particulate matter (PM2.5) and increased mortality [37-40,51,52]. As an example, in a longitudinal study of the population of six United States cities followed for 14 to 16 years (mid-1970s through 1990), increased air pollution was associated with increased mortality; this increased mortality was most closely associated with the increase in fine particulate pollution [41]. Furthermore, a dose response was observed, with an increased mortality rate of 13 percent for every 10 mcg/m3 rise in PM2.5 (1.16, 95% CI 1.07-1.26) [41]. With extended follow-up in the same cities, there were improvements in air quality with a decrease in PM2.5; this decrease was associated with improvements in mortality risk [53].
In addition, even a short-term increase in levels of pollution (including particulate pollution and ozone) is associated with a rise in daily all-cause mortality [51,54]. In a time-series study including over 650 cities in 24 countries, increases of 10 mcg/m3 in the two-day average PM2.5 and PM10 were associated with an increase in daily all-cause mortality (0.68, 95% CI 0.59-0.77 and 0.44, 95% CI 0.39-0.50, respectively) [51]. In regions with better overall air quality, the observed dose response effect was greater with no threshold for effects, thus implying that even countries with relatively good air quality could still see public health benefits from further reduction in PM [55].
Wildfires, which have become more frequent and intense, and which often include buildings as well as vegetation, lead to the emission of high levels of natural and building material-related air pollutants along with fine particulate matter (PM2.5) [56]. Exposure to wildfire smoke has been associated with both short- and long-term adverse health effects, including pulmonary, cardiovascular, cerebrovascular, and psychological [56-59]. Preliminary research has also raised concerns about the increased risks posed by wildfires and high levels of air pollution on the frequency and severity of COVID-19 infections [31,59,60].
Air pollution is also associated with adverse health effects in children, including infant brain development, lung development and function (including asthma), and mortality rates [61-63]. The United Nations International Children’s Emergency Fund (UNICEF) has estimated that approximately 300 million children live in regions where air pollution exceeds standards by at least sixfold, and it is the major contributor to the deaths of 600,000 children under the age of five annually [64]. Improved air quality can benefit the health of all children, not only those with lung disease. As an example, in a cohort study evaluating the pulmonary function of children ages 11 to 15 years with and without asthma, better air quality (decreased levels of nitrogen dioxide and particular matter) was associated with improvements in both forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) [65].
Climate change and adverse health effects — Burning of fossil fuels leads to the emission of carbon dioxide, methane, and nitrous oxides (“greenhouse gases”), as well as particulate matter and sulfur dioxides into the air. Compared with preindustrial levels, carbon dioxide has risen from approximately 280 to 414.72 ppm (2021), leading to a rise in the mean earth surface temperature to 1.1°C and warming and acidification of the oceans [66-68].
Climate change has resulted in record heat, increased likelihood of wildfires, severe weather events (eg, heat waves, floods, severe hurricanes, droughts), poorer air quality, and sea level rise [59,66]. There is also a reinforcing and synergistic interplay between wildfires and climate change [59]. These climate effects have major health consequences and increased health risks, including injuries, heat-related illness and death, exacerbations of respiratory and cardiovascular disease, infectious diseases, changes in vector-related diseases [69], and physical and mental health effects related to forced migration (figure 1) [66,70,71]. Children will be among the most vulnerable groups affected by climate change [12,72].
More adverse effects are anticipated if the average increase in surface temperature continues to rise above 1.5°C, and thus there is a greater imperative to further cut greenhouse gas emissions [73,74].
In the clinic, during warm months, providers should ask their patients if they have a way to stay cool when the weather is very hot, and also inquire whether they have a job that places them in a hot environment (such as indoors in kitchens, or outdoors, like roofers), or whether they exercise outside. Providers can identify patients at risk for heat related illness [4], and provide education about early recognition and preventive actions (see resources here). Workers can consult the Occupational Safety and Health Administration heat website and get the heat safety tool app downloaded to their smart phone.
Climate emergencies including heat, wildfires, floods, and hurricanes are discussed separately. (See "Climate emergencies".)
Other environmental exposures
●Environmental exposures at home (eg, to dust mites and cockroaches) [75] and at work [16,76] appear to have contributed to the increased incidence and mortality of asthma in both adults and children [77]. In addition, concerns continue to be raised about potential health effects related to dampness and mold in indoor environments [78,79], including exacerbation of asthma [80]. (See "Allergen avoidance in the treatment of asthma and allergic rhinitis", section on 'Cockroaches' and "Trigger control to enhance asthma management", section on 'Indoor air pollution' and "Trigger control to enhance asthma management", section on 'Workplace irritants'.)
●Increased attention has been directed to the contributions of the built environment (eg, homes, buildings, streets, infrastructure) to adverse health effects including asthma, obesity, lead poisoning, and traffic accidents. These conditions disproportionately affect people living in poverty and people of color [81-86]. (See "Trigger control to enhance asthma management", section on 'Indoor air pollution' and "Lead exposure, toxicity, and poisoning in adults".)
Increasing initiatives of a “healthy building movement” promote the creation of buildings that support the health and wellbeing of the people inside [87]. The indoor air environment has taken on even greater importance during COVID-19 [88]. (See "Building-related illness and building-related symptoms", section on 'Indoor air quality'.)
●Consumers have exposure to potentially harmful nanoparticles through the use of numerous common products including clothing, sunscreens, and cosmetics. The US Food and Drug Administration (FDA) is formulating an approach to regulation [89,90]. (See "Selection of sunscreen and sun-protective measures", section on 'Safety'.)
●Pediatric environmental health – In the United States, a percentage of many pediatric diseases can be attributed to an environmental exposure: lead poisoning (100 percent); asthma (30 percent, range between 10 to 35 percent); cancer (5 percent, range between 2 to 10 percent); and neurobehavioral disorders (10 percent, range between 5 to 20 percent) [91]. The number of recognized neurodevelopmental toxins continues to expand [92]. (See "Childhood lead poisoning: Clinical manifestations and diagnosis".) There are several valuable resources on pediatric environmental health, including printed material [93] as well a network of Pediatric Environmental Health Specialty Units with resources available to health care providers and the general public.
●Per-and polyfluoroalkyl substances (PFAS) [7] are long-lasting, man-made chemicals that are resistant to water, oil, and fire; thus making them useful in a wide range of consumer and industrial products, including aqueous film-forming firefighting foam, food containers/wrapping, nonstick cookware, carpeting and clothing non stain treatment, and waterproofed clothing [7]. Population exposures are widespread and can occur through ingestion or inhalation through various pathways, such as drinking water, air, dust, food containers, cookware, and breast milk. PFAS bind to tissue proteins and accumulate in blood along with lower levels in the liver, kidneys, and brain. These chemicals have little to no metabolism and are primarily excreted through urine. Some stay in the body for varying lengths of time, but it can be decades [94]. Population concerns have grown since more communities have been told that PFAS have been detected in their water. Most people in the United States Have been exposed to PFAS, with the most common ones being perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) [95].
Clinicians may be contacted by their patients who receive reports showing elevated PFAS levels in their drinking water. States have designated different health advisory levels: some have given a level for any PFAS, others for a sum of designated ones. These differing numbers given for the acceptable or “safe” levels create challenges for clinicians interpreting the water test results.
Research studies in animals and humans are still ongoing. The National Academy of Sciences Committee reviewed PFAS studies and produced a report [96] that summarized the findings on health impacts of PFAS exposure as follows [97]:
•There is sufficient evidence of association between PFAS exposure and an increased risk of decreased antibody response in adults and children, dyslipidemia in adults and children, decreased infant and fetal growth, and kidney cancer in adults. (See "Occupational and environmental risks to reproduction in females: Specific exposures and impact".)
•There is limited or suggestive evidence of an increased risk of breast cancer in adults, liver enzyme alterations in adults and children, pregnancy-induced hypertension, increased risk of testicular cancer in adults, thyroid disease and dysfunction in adults, and increased risk of ulcerative colitis in adults.
This leads to the next question, whether exposed individuals should get tests to measure PFAS in their blood. Although some of these chemicals can be measured in the blood and compared with population levels, there have been only limited correlations of measured levels and risk of adverse outcomes. Therefore, we have been hesitant to advise routine blood testing, since it is difficult to interpret, or offer specific advice, other than to stop the exposure. However, the 2022 US National Academies of Sciences report [97,98] suggests a role for PFAS blood testing for those patients “who are likely to have a history of elevated exposure.” This includes those with occupational exposures (such as firefighters), those who live in communities where PFAS contamination has been documented (eg, drinking water that exceeds regulatory limits) or those who live near PFAS-contaminated facilities.
The National Academies of Sciences report suggests the following approach based upon the sum of serum or plasma concentrations of seven PFAS named by the committee:
•For patients with PFAS blood concentrations below 2 ng/mL, no adverse effects would be expected.
•Patients with test results between 2 to 20 ng/mL may face potential adverse effects, especially in sensitive populations (such as pregnant persons). Clinicians should encourage reduction of PFAS exposure. “Following the usual standard of care, clinicians should also prioritize screening for dyslipidemia, hypertensive disorders of pregnancy, and breast cancer based on age and other risk factors” [98].
•Patients with test results above 20 ng/mL may face a higher risk of adverse effects. In addition to the above recommendations (for those between 2 and 20 ng/mL), clinicians should also conduct thyroid function testing and assess for signs of kidney and testicular cancer and ulcerative colitis at all wellness visits.
In counseling patients, it is also important to note that there is currently no way to remove or enhance excretion of the PFAS chemicals from the body. In addition, the costs of the PFAS blood tests may not be paid by health insurance, particularly in the absence of a relevant symptom or diagnosis. One justification for getting some blood testing, particularly for the particular PFAS found elevated in the drinking water, would be to have a baseline measurement noted, so that it would be available if at some later time new information arises that would be useful.
Regardless of any blood test results, known exposure should be stopped or reduced to the amount feasible. Drinking water, for example, can be substituted or filtered.
CLINICAL PRESENTATIONS — Environmental and work exposures can cause or aggravate a variety of common diseases such as asthma, carpal tunnel syndrome, dermatitis, hepatitis B, and cancer. In many cases, the work- or environment-related illnesses do not have unique clinical presentations: asthma caused by latex allergy does not differ from asthma precipitated by a cat allergy; median nerve entrapment related to acute trauma or repetitive motions has the same constellation of symptoms and signs as carpal tunnel syndrome related to pregnancy; headache due to carbon monoxide poisoning can be mistaken for severe tension headache or migraine. Symptoms related to hazardous exposures can appear as complaints involving any body system and mimicking ordinary medical diseases (table 1 and table 2). Some exposures cause immediate or subacute symptoms (such as allergic reactions and acute chemical reactions), while others lead to more delayed effects (such as cancer or pneumoconiosis). The distinguishing feature is the linkage to an environmental or occupational exposure. The occupational and environmental history can be the critical first step in recognizing, treating, and preventing environmental/occupational illnesses and injuries (algorithm 1).
OCCUPATIONAL AND ENVIRONMENTAL HISTORY — The first step in the occupational/environmental history is a survey of all patients, including relevant questions and attention to the chief complaint (or diagnosis) for clues suggesting a relationship to activities at work or at home (algorithm 1) [3,99,100]. Questions may include a list of current and longest-held jobs, a brief current job description, and inquiries about changes in or concerns regarding exposures or hazards at work or at home, including risks related to hot environments.
In looking for a temporal relationship to work, it is better to start with non-suggestive questions such as, "Are your symptoms better or worse at home or at work? Weekends or work days?" rather than more leading questions such as, "Does work make you sick?" Any suggestion that the symptoms may be related to recent or past exposures, or to some change in environment, either at work or at home, then precipitates a more detailed series of questions to obtain additional information about potential exposures and timing of work- or environment-related symptoms.
In some cases, the screening occupational environmental survey reveals suggestive temporal relationships pointing to the role of environmental/work factors: the painter who has been scraping old paint and has abdominal pain (lead poisoning?); the lab technician who gets hand itching and a rash when they put on latex gloves (allergy?); the household members who develop headaches in the fall that are worse in the morning and when at home (carbon monoxide poisoning due to a faulty furnace?).
Some cases of acute poisoning present with the sudden onset of characteristic signs and symptoms ("toxidromes"), due to accidental or deliberate release of toxicants, which need prompt recognition and treatment, frequently before diagnostic laboratory tests of the poison can be obtained [5,101]. As an example, persons presenting with miosis, dim vision, eye pain, rhinorrhea, headache, sweating, and diarrhea should raise strong suspicions of overdose with a cholinesterase inhibitor, such as an organophosphate pesticide or sarin nerve gas. When a religious cult released a toxic nerve gas in the subway system in Tokyo, 5000 persons required emergency treatment, and 11 died [102]. (See "Chemical terrorism: Rapid recognition and initial medical management".)
Finding a clear temporal relationship between symptoms and exposure is useful, but it is also important to realize that in some cases current exposures do not always lead to immediate symptoms. As examples:
●A car painter may have worked for months at their job before developing a dry hacking cough that occurs during or after work. They might be experiencing bronchospasm from exposure to toluene diisocyanate (TDI), a well-known sensitizing agent, and one of the chemical components in the car lacquer that they spray. In the case of allergic responses, it may take months of exposure before sensitization and clinical allergy develops. Once the asthma occurs, symptoms can sometimes extend beyond the work period and then be triggered by a range of irritants. (See "Occupational asthma: Clinical features, evaluation, and diagnosis".)
●Symptoms of hyperreactive airways (persistent dry cough and shortness of breath) may develop after a single large exposure to an irritant such as chlorine gas or sulfur dioxide. This has been termed "reactive airways disease syndrome" (RADS) [103]. Some firefighters and rescue workers exposed to a variety of inhaled materials during and after the collapse of the Twin Towers at the World Trade Center developed severe cough and persistent bronchial hyperreactivity [104-107]. The term "irritant-induced occupational asthma" has less stringent criteria than RADS including cases with induced airway symptoms after one or more exposures [16,108]. (See "Irritant-induced asthma".)
Symptoms related to current exposures may improve on non-work days or vacations early in the course of illness, a helpful clue to the potential relationship with work. However, prolonged exposure can lead to the persistence of symptoms beyond the work week. As an example, aching in the wrist and hand of a stitcher due to repetitive wrist flexion and pinching, or from a data entry worker keying on a poorly positioned keyboard, might initially resolve with rest in the evenings or on weekends. Once carpal tunnel syndrome or chronic tendonitis develops, the symptoms can persist into non-work time and be aggravated by other activities such as sewing, instrument playing, or gardening. Furthermore, other diseases such as cancer or asbestosis may occur with a long latency (15 to 30 years from the time of exposure to the onset of the disease). (See "Asbestos-related pleuropulmonary disease".)
Some diagnoses, termed "sentinel health events" (SHE), are more likely to be linked to current or past jobs. A SHE (occupational) is a disease, disability, or untimely death that is occupationally related and whose occurrence may provide the impetus for evaluation and interventions that prevent future cases [109,110]. A patient diagnosed with a SHE, such as pulmonary tuberculosis, asthma, contact dermatitis, mesothelioma, bladder cancer, peripheral neuropathy, or pulmonary fibrosis, would be another prompt to taking a more detailed occupational/environmental history in pursuit of potential underlying (preventable) exposures. Sometimes, recognition of unusual presentations, particularly when seen in groups of workers, leads to discovery of new diseases, such as a cluster of employees in a nylon flocking plant who presented with interstitial lung disease ("flock workers lung") [111,112] and groups of workers from a plant producing microwave popcorn who developed bronchiolitis obliterans ("popcorn lung") found to be caused by a butter flavoring additive, diacetyl [113,114].
The occurrence of an illness in an unexpected person (eg, bladder or lung cancer in a young nonsmoker) should prompt the clinician to delve further into potential contributing environmental or occupational exposures. In another situation, work or home exposures may appear to worsen an underlying medical illness. Symptoms with no clear etiology may indicate toxicological etiologies.
The practitioner needs to proceed with more detailed questioning once there is a suspicion that symptoms could be related to occupational or environmental conditions. Questions should include the place of employment and products manufactured. The worker should describe the tasks they perform, the agents handled, and the working conditions. Getting more information about chemical exposures can be initiated with obtaining the generic names of the agents used. This can be accomplished by having the patient bring in a label or a Safety Data Sheet (SDS; previously referred to as a Material Safety Data Sheet [MSDS]); the latter is the manufacturer's description of the product's generic name, ingredients, known health hazards, and recommendation for safe handling. These sheets vary in accuracy and completeness [100,115]. The SDS can be obtained from the manufacturer or employer, and some can be found on internet sites. Information about health effects related to these toxins can also be found by consulting other sources such as poison control centers (in the United States, dial 1-800-222-1222), consultants, agencies, and useful references.
Once it is clear what is being handled, the next question is whether or not there is an opportunity for actual exposure. The patient should describe how a substance is handled: What are the operating or cleanup practices? What protective measures are used? What type of ventilation and exhaust is provided? Does the worker need to wear a respirator, and, if so, is it the proper respirator, and is it worn and properly maintained? A good source for information about respirators can be found at the NIOSH website. Then consider the mode of entry: Is it inhaled? Is it ingested by eating at the workplace? Is there skin contact? Is there use of protective clothing or appropriate gloves to prevent skin absorption? Are other workers exposed? Do others have any symptoms?
It is also helpful to consider if the person exposed may be particularly vulnerable to the exposure. A person with kidney disease, as an example, exposed to lead at acceptable (regulatory) air levels, might accumulate higher levels of lead than expected because of decreased ability to excrete it through the diseased kidneys. A pregnant person might be exposed to toxins, such as lead or carbon monoxide, at doses that would not be dangerous to the adult but would be harmful to the developing fetus, who is more sensitive to the adverse effects (see "Overview of occupational and environmental risks to reproduction in females" and "Occupational and environmental risks to reproduction in females: Specific exposures and impact"). An older adult patient living in an upper level of a building without air conditioning may be at risk for heat stress, as is a worker who is doing outside work such as roofing. If individuals are identified with the potential for heat-related illnesses, measures could be suggested that would prevent symptoms [4].
Exposures also can occur inside or outside of the home. Household exposures may result from the use of household chemicals, performance of certain hobbies, home remodeling, or bringing home contaminated work clothing (table 3 and table 4). A household products database is available on the National Library of Medicine website and provides health effect information on over 4000 consumer brands.
The home and schools, as well as the surrounding air, water, and soil, can be contaminated by nearby industrial plants, commercial business, or dump sites or through disasters such as hurricanes, flooding, or earthquakes. Depending upon the patient's complaints, inquiry about home insulation, heating and cooling systems, home cleaning agents, pesticide use, water supply, water leaks, recent renovations, air pollution, hobbies, hazardous waste contamination, spills, floods, or other exposures may be warranted. The potential for exposure to children should be considered if possible when home, school, or neighborhood exposures are identified.
Pediatric environmental health history — A child's physiology and behavior puts them at an increased risk for adverse effects from many toxins. Most attention concerning environmental exposures to children previously centered upon lead and secondhand tobacco smoke. There has been increasing awareness about the potential health effects of other exposures, including chemical allergens and irritants (eg, formaldehyde resins), indoor and outdoor air pollutants, pesticides, and other toxins [93,116]. The pediatric history involves asking screening questions at the initial visit and follow-up visits that are relevant to the child's developmental stage. Questions are directed toward describing the home or other environments frequented by the child, as well as household members' jobs [93]. (See "Secondhand smoke exposure: Effects in children" and 'Other environmental exposures' above.)
DOCUMENTING AND QUANTIFYING EXPOSURE — If the history raises concerns about exposures, it is usually necessary to measure the exposure in order to assess the level of risk and/or relationship to any symptoms. Documenting and quantifying exposures can involve performing biological monitoring tests of the affected person as well as evaluating the work or environmental site. The practitioner may find it helpful to seek assistance from specialists such as occupational/environmental medicine specialists, toxicologists, governmental agencies, and industrial hygienists.
Within the office setting, the patient can be tested for evidence of exposure in body fluids (biological monitoring) or evidence of adverse health effects on target organs. The practitioner must know what agent to look for, the desirable test medium (urine, blood, hair, tissue), appropriate timing, and influences upon test results [117-119].
●Carbon monoxide exposure is measured with a carboxyhemoglobin blood test; measurement of carboxyhemoglobin should be performed as soon as possible after exposure since the half-life of carbon monoxide in the body is approximately six to eight hours when breathing room air. (See "Carbon monoxide poisoning".)
●Arsenic is excreted rapidly in the urine within a few days; it is a good marker for recent but not past exposure. Recent consumption of seafood can lead to increases in total urine arsenic due to the contribution of relatively nontoxic forms of organified arsenic, thereby leading to mistaken interpretations of elevated arsenic levels. The solution is to speciate (or fractionate) urine arsenic into inorganic and organic arsenic if elevated levels are identified. (See "Arsenic exposure and chronic poisoning".)
●Some chemicals are detected by measurement of metabolites. As an example, several biological monitoring tests have been proposed for evaluating exposure to the solvent toluene, including measurements of the urine metabolites hippuric acid, benzoic acid, and o-cresol [117-119]. These tests, however, tend to be less specific, and timing is important. In some cases, environmental sampling is more fruitful for estimating exposure.
●Hair analysis performed by commercial laboratories for multiple toxins and elements have been found to be of poor reliability and accuracy and have little applicability in the primary care setting [120,121]. On rare occasions, however, it might be useful to obtain a hair analysis for a single element performed by an accredited commercial laboratory with experience in performing such analyses.
Laboratory tests may also be performed to look for toxic effects or end-organ damage. As an example, a blood lead concentration could be ordered to assess exposure, and blood urea nitrogen (BUN) and creatinine could be ordered to look for effects upon the kidneys. Pulmonary function tests and a chest radiograph and/or computed tomography (CT) would be ordered to assess the effects of past asbestos exposure on the lungs. (See "Asbestos-related pleuropulmonary disease".)
Some providers (sometimes termed “functional” or “alternative” practitioners) give a chelating agent (such as dimercaptosuccinic acid [DMSA]) prior to measuring urinary metals, compare those results with a healthy, non-provoked population, and then make interpretations about body burden and metal toxicity. This is a practice that is not evidence-based, and, as noted in the American College of Medical Toxicology position statement: "post-challenge urinary metal testing has not been scientifically validated, has no demonstrated benefit, and may be harmful when applied in the assessment and treatment of patients in whom there is concern for metal poisoning" [122,123].
Examination of the environmental or occupational site can be performed by governmental agencies, such as the Occupational Safety and Health Administration (OSHA) or the Environmental Protection Agency (EPA), or by private consultants such as certified industrial hygienists. Air sampling is performed with area or personal sampling devices to get results that can lead to estimates of exposure based upon an average eight-hour exposure. Many regulatory standards such as OSHA permissible exposure limits (PELs) are based upon eight-hour, time-weighted averages. However, many of the OSHA standards have not been updated. Toxins can be measured in air, water, soil, and from surfaces.
In some cases, the correlation between exposure levels (in the environment or the body) and health effects is good, and in other cases it is poor. Lead, as an example, can be measured in air (micrograms/cubic meter) with a reasonable correlation between air levels and blood leads measured in exposed individuals. Although there is considerable individual variation, there is a general correlation between recent lead exposure and acute clinical responses in adults. Generally, there are little or no acute clinical effects from recent exposures leading to blood lead concentration below 20 micrograms/dL in adults; gastrointestinal symptoms may occur with levels of 50 micrograms/dL and above, and anemia seen with levels above 80 micrograms/dL. By contrast, manganese levels (of potential importance since an organic form of manganese, methylcyclopentadienyl manganese tricarbonyl [MMT], has been used as a gasoline additive) measured in the air are poorly correlated with measurement in the blood. In general, blood levels of manganese do not correlate well with the appearance of the adverse side effects of manic-depressive symptoms and parkinsonism. (See "Lead exposure, toxicity, and poisoning in adults".)
Assessment of musculoskeletal stresses can be performed qualitatively, by observing the workers performing job tasks, and more quantitatively with biomechanical analyses performed by an ergonomics expert.
MAKING A CAUSAL CONNECTION BETWEEN EXPOSURE AND ILLNESS — Making the causal connection between an exposure and the patient's symptoms requires consistency between the known adverse effects of the toxic agent and the nature of the illness; the presence of an appropriate temporal relationship between exposure and effect; and a sufficient exposure to cause the presumed effect. There are a number of excellent resources describing the health effects of various exposures [124-128], as well as agencies and consultants to whom the primary care clinician can turn for assistance in this process.
Poison control centers are another resource that provides quick information about chemical toxins (in the United States, dial 1-800-222-1222). There has been a great deal of publicity about health effects and exposure to damp environments and mold, and there are several excellent resources that summarize current information and approaches [78,80,129-131]. (See "Building-related illness and building-related symptoms", section on 'Mold'.)
FOLLOW-UP — It is important to consider whether others have been exposed and need to be evaluated and treated once the diagnosis of a work- or environment-related illness has been made. It may be necessary to make an intervention to decrease or eliminate exposures in order to prevent illness in others. The clinician may find it necessary to alert the company medical department, a company health and safety committee, or the state public health or labor department. It is often necessary to obtain additional exposure information to follow up on the initial leads. The Occupational Safety and Health Administration (OSHA) performs work site inspections on a priority basis or at the request of a current worker or management. Fines may be levied in some cases if OSHA standards are violated.
Other consultative sources include academically affiliated occupational health clinics (Association of Occupational and Environmental Clinics), board-certified occupational and environmental medicine specialists (American College of Occupational and Environmental Medicine), Pediatric Environmental Health Specialty Units, and worker education/advocacy groups such as Coalition for Safety and Health (COSH) groups. The National Institute for Occupational Safety and Health (NIOSH) can provide the practitioner with toxicological information and perform health hazard evaluations of workers to detect work-related health problems. Industrial hygienists from private consulting groups or from workers' compensation carriers can conduct worksite evaluations and monitoring and advise about interventions. The practitioner may find it useful to contact the local state Department of Environmental Protection or city departments of public health for environmental problems.
The practitioner can also help an affected worker obtain workers' compensation when justified. The definition of "work-related" may vary by state but usually implies that it is more likely than not that some activity at work precipitated, hastened, aggravated, or contributed to the injury or illness. The workers' compensation system is state-based; the practitioner needs to become familiar with the state regulations of their practice. Workers' compensation can provide benefits for work time lost, permanent disability, medical care expenses, and rehabilitation.
Efforts to control home environmental exposures can also be helpful. As an example, practitioners can advise asthmatic patients on measures to reduce environmental triggers. For example, a study of children with asthma, interventions that resulted in reducing levels of cockroach allergen and dust mite allergen in the bedroom were significantly correlated with reduced complications from asthma [132]. (See "Allergen avoidance in the treatment of asthma and allergic rhinitis", section on 'Cockroaches' and "Allergen avoidance in the treatment of asthma and allergic rhinitis", section on 'Dust mites'.)
SUMMARY AND RECOMMENDATIONS
●Roles of the clinician – Clinicians need to know how to take a good environmental and occupational history and should have a reasonable understanding of common environmental-related illnesses and injuries as well as basics of exposure assessment. Clinicians also have an opportunity for preventive care related to environmental and climate-related exposures. A patient's reported exposures may prompt important interventions to prevent future illnesses or injuries for the patient and for others. (See 'Roles of the clinician' above.)
●Relationship of exposures to clinical presentation – Although many work-related illnesses and injuries may be easily identified by known precipitants, some may only become apparent after a prolonged period of exposure. Work or environmental exposures, including work-exacerbated asthma (WEA) or occupational exposure to toxic substances, work-related injuries, exposure to air pollution, or injury and illness related to climate change, may be linked to an individual patient's symptoms. (See 'Epidemiology' above and 'Clinical presentations' above.)
●Taking an occupational/environmental exposure history – The first step in the occupational/environmental history is a survey of all patients, including relevant questions (noting current and longest-held job as well as any concerns about exposures at work or at home, including attention to heat) and attention to the chief complaint (or diagnosis) for clues suggesting a relationship to activities at work or at home (algorithm 1). Questions may include a list of current and longest-held jobs, a brief current job description, and inquiries about changes in or concerns regarding exposures or hazards at work or at home. (See 'Occupational and environmental history' above.)
●Documenting and quantifying the exposure – If the history raises concerns about exposures, it is usually advisable to measure the exposure in order to assess the level of risk and/or relationship to any symptoms. Documenting and quantifying exposures can involve performing biological monitoring tests of the affected person as well as evaluating the work or environmental site. (See 'Documenting and quantifying exposure' above.)
●Follow-up after the diagnosis of occupational- or environmental-related illness – It is important to consider whether others have been exposed and need to be evaluated and treated once the diagnosis of a work- or environment-related illness has been made. It may be necessary to make an intervention to decrease or eliminate exposures in order to prevent illness in others. (See 'Follow-up' above.)
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