Environmental Exposures and Health: An Introduction for Clinicians
Level 2, Intermediate
In brief
Environmental exposures contribute substantially to global disease. Air pollution, lead, household smoke from solid fuels, tobacco smoke, radon, arsenic in groundwater and occupational hazards have strong evidence of harm. Endocrine disrupting chemicals, PFAS and microplastics are areas of active research with emerging evidence. A structured environmental history identifies relevant exposures, and practical, proportionate steps can reduce them without creating unnecessary fear.
Every person’s health reflects not only their genes and behaviours but the air they breathe, the water they drink, the homes and workplaces they inhabit and the products they use. The concept of the exposome, proposed in the mid 2000s, describes the totality of environmental exposures across a lifetime, a counterpart to the genome. Some of these exposures are among the largest causes of disease in the world; others are the subject of intense public concern with far less certain effects. Practitioners need to know the difference.
Exposures with strong evidence of harm
Air pollution
Outdoor air pollution, particularly fine particulate matter, is one of the leading environmental causes of death worldwide, contributing to heart disease, stroke, lung cancer, chronic lung disease, lower respiratory infections and adverse pregnancy outcomes. The World Health Organization lowered its guideline for annual fine particulate matter in 2021, reflecting evidence of harm at lower concentrations than previously recognised. Most of the world’s population lives in areas exceeding the guideline. Air pollution is also among the modifiable risk factors for dementia.
Household air pollution
Cooking and heating with solid fuels such as wood, charcoal, dung and coal in poorly ventilated homes exposes billions of people, particularly women and children, to high levels of smoke. The World Health Organization estimates that household air pollution causes several million deaths each year.
Lead
There is no known safe level of lead exposure. In children, lead impairs cognitive development even at low levels. In adults, it raises blood pressure and cardiovascular risk. Sources include old paint and dust, old water pipes, contaminated soil, some occupations, some imported ceramics and spices, and some traditional remedies and cosmetics.
Tobacco smoke
Secondhand smoke exposure increases the risk of heart disease, lung cancer, asthma and sudden infant death.
Radon
Radon, a naturally occurring radioactive gas that can accumulate in homes, is the second leading cause of lung cancer after smoking in many countries. Testing and mitigation are straightforward.
Arsenic
Naturally occurring arsenic in groundwater affects millions of people, notably in parts of South Asia, and causes skin lesions, cancers, cardiovascular disease and diabetes.
Occupational exposures
Silica, asbestos, diesel exhaust, solvents, pesticides and other workplace exposures cause lung disease, cancers and other conditions. Occupational history is essential.
Exposures under active research
| Exposure | Current understanding |
|---|---|
| Endocrine disrupting chemicals, such as bisphenol A and phthalates | Interfere with hormonal signalling in experimental studies; associations with reproductive and metabolic outcomes in humans; regulators in several regions have restricted some uses; effects at typical exposures remain debated |
| PFAS, per and polyfluoroalkyl substances | Persistent chemicals widely detected in blood; associated with changes in cholesterol, immune responses to vaccines and some cancers; the International Agency for Research on Cancer classified PFOA as carcinogenic to humans in 2023 |
| Microplastics and nanoplastics | Detected in human tissues; a study found that people with microplastics in carotid artery plaque had higher rates of subsequent cardiovascular events; causation not established |
| Pesticides | Some organophosphates associated with neurodevelopmental effects; occupational exposures associated with some diseases |
| Noise | Chronic traffic noise associated with cardiovascular disease and sleep disturbance |
| Heat | Extreme heat increases mortality, particularly in older adults and people with chronic disease |
Who is most vulnerable
- Fetuses, infants and children, whose developing systems are more sensitive and who have higher exposures relative to body size.
- Pregnant women.
- Older adults and people with chronic disease.
- People with occupational exposures.
- People in low income communities, who often live closer to pollution sources and in older housing.
Taking an environmental history
A structured history helps identify relevant exposures without overwhelming the consultation. A widely used framework covers several areas:
- Community: proximity to traffic, industry, agriculture or waste sites; local air quality; water source.
- Home: age of housing, heating and cooking methods, damp and mould, water pipes, renovations.
- Hobbies: activities involving solvents, metals, ceramics, firearms, gardening chemicals.
- Occupation: current and past jobs and exposures, protective equipment.
- Personal habits: smoking, vaping and alcohol.
- Diet: fish intake, water source, imported foods or spices, traditional remedies.
- Drugs and products: medicines, supplements, cosmetics and skin lightening products.
Proportionate responses
Environmental health can generate anxiety, and patients may encounter alarming claims about toxins. A proportionate approach focuses on exposures with the strongest evidence and the most practical solutions.
| Priority | Practical steps |
|---|---|
| Tobacco smoke | Smoking cessation; smoke free homes and cars |
| Air pollution | Checking air quality alerts, reducing outdoor exertion on high pollution days, indoor air filtration where affordable, avoiding solid fuel indoors, ventilation when cooking |
| Lead | Testing children in older housing or with risk factors, safe renovation practices, flushing and testing water in older homes, avoiding contaminated products |
| Radon | Testing homes in radon affected areas |
| Water | Testing private wells, particularly for arsenic where relevant |
| Fish | Choosing lower mercury fish, especially in pregnancy |
| Plastics and chemicals | Reasonable, low cost steps: avoid heating food in plastic, prefer fresh foods over heavily packaged ones, ventilate after using cleaning products |
It is equally important to avoid unvalidated tests and expensive detoxification products marketed on the basis of environmental fears, which are discussed in later articles.
An illustrative case
A family with a 2 year old child moves into an old house and begins renovations. The child becomes irritable and constipated, and the mother, who is pregnant, has headaches. The practitioner’s environmental history identifies sanding of old paint during the renovation. The child’s blood lead level is raised, as is the mother’s. Renovation is stopped until professional lead safe remediation is arranged, the family moves temporarily, and the child’s nutrition is reviewed, as iron and calcium deficiency increase lead absorption. Follow up testing shows falling levels. A single question about the home made the diagnosis.
Environment as a determinant of health
Environmental exposures are powerful determinants of health, and some of the largest are also among the most preventable. An environmental history, focused on exposures with strong evidence and followed by practical steps, allows practitioners to protect patients without adding to unnecessary fear.
Environmental health questions
Which environmental exposures cause the most harm?
How should practitioners take an environmental history?
Are microplastics harmful?
References
- Wild CP. Complementing the genome with an exposome: the outstanding challenge of environmental exposure measurement in molecular epidemiology. Cancer Epidemiology, Biomarkers and Prevention. 2005;14(8).
- World Health Organization. WHO global air quality guidelines: particulate matter, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. Geneva: WHO; 2021.
- Lanphear BP, Rauch S, Auinger P, et al. Low level lead exposure and mortality in US adults: a population based cohort study. The Lancet Public Health. 2018;3(4).
- Marfella R, Prattichizzo F, Sardu C, et al. Microplastics and nanoplastics in atheromas and cardiovascular events. New England Journal of Medicine. 2024;390(10).
- Zahm S, Bonde JP, Chiu WA, et al. Carcinogenicity of perfluorooctanoic acid and perfluorooctanesulfonic acid. The Lancet Oncology. 2024;25(1).
- Gore AC, Chappell VA, Fenton SE, et al. EDC 2: the Endocrine Society’s second scientific statement on endocrine disrupting chemicals. Endocrine Reviews. 2015;36(6).
Continue your learning
Taking an environmental history
The environment appears on many patient timelines as an antecedent or trigger. IIFM’s 6 month Functional Medicine and Clinical Nutrition program, particularly its Detoxification module, teaches practitioners to assess exposures proportionately.
This article is for the education of healthcare professionals. It is not a substitute for individual medical advice, diagnosis or treatment, and does not change any practitioner’s scope of practice. Regulation and guidelines differ between countries.