Environmental Exposures and Health

Environmental exposures and health concerns the influence of agents in the general (non-occupational) environment — pollutants in air, water, soil, and food, along with the built environment and climate — on the occurrence of chronic disease. These exposures are typically widespread, involuntary, and low-level, so that even small per-person effects can translate into a large population burden.

Definition

Environmental exposure refers to contact with chemical, physical, or biological agents present in the ambient environment outside the workplace; the topic addresses the epidemiologic study of how such exposures relate to chronic disease.

Scope

The topic frames the methods used to link environmental agents to disease, including the concept of the exposome, the importance of windows of susceptibility such as early life, and the challenge of estimating effects of ubiquitous low-dose exposures. It is a reference treatment of how environmental risks are studied, not advice on personal exposure reduction.

Key concepts

• Exposome
• Windows of susceptibility
• Low-dose / ubiquitous exposure
• Ecologic study design
• Biomarkers of exposure
• Population attributable fraction
• Ultrafine particles

Key theories

Developmental origins of health and disease (DOHaD)

Exposures and conditions during critical windows of development, particularly in utero and early life, can programme tissue structure and function in ways that alter susceptibility to chronic disease decades later, framing the timing of environmental exposure as causally important.

Mechanisms

Environmental agents enter the body through inhalation, ingestion, and dermal contact, and may act through inflammation, oxidative stress, endocrine disruption, or direct genotoxicity. Because everyday exposures are often low-level and nearly universal, contrasts across the population are small, and epidemiologic study relies on biomarkers, spatial exposure models, and large cohorts to detect effects. The exposome concept frames the totality of environmental exposures across the life course as a determinant of disease alongside the genome.

Clinical relevance

Environmental exposures contribute to cancers, cardiovascular and respiratory disease, neurodevelopmental disorders, and other chronic conditions, and identifying them underpins environmental health policy. This entry is a reference account of how those associations are established in populations and is not a basis for individual diagnosis or treatment.

Epidemiology

The Lancet Commission on pollution and health attributed millions of premature deaths each year to environmental pollution, predominantly from non-communicable diseases and falling disproportionately on low- and middle-income countries. Even agents present at very low ambient concentrations, such as ultrafine particles and certain metals, can register measurable population effects because exposure is so widespread.

History

Concern with the environment and health is ancient, but modern environmental epidemiology took shape after mid-twentieth-century episodes such as the London smog of 1952 and recognition of waterborne and chemical hazards. The exposome concept, articulated by Christopher Wild in 2005, reframed the field around measuring the full range of life-course exposures, while developmental-origins research extended attention to early-life windows.

Key figures

• Philip Landrigan
• Christopher Wild
• Günter Oberdörster
• Peter Gluckman

Seminal works

• landrigan-2018
• gluckman-2008
• oberdorster-2005

Frequently asked questions

What is the exposome?

The exposome is the totality of environmental exposures an individual experiences across the life course, proposed as a complement to the genome for understanding the environmental contribution to chronic disease.

Why are low-level environmental exposures still important?

Because such exposures affect almost everyone, even a small increase in individual risk can produce a substantial number of cases at the population level, which is why ubiquitous low-dose agents receive close epidemiologic attention.