Background
Chemical pollution significantly affects human health through two primary mechanisms: direct and indirect exposure, both contributing to a substantial global health burden.
Direct Effects from Exposure
Direct effects occur when humans come into contact with pollutants in the environment—breathing contaminated air, ingesting polluted water, food, or soil, or through dermal contact with contaminated surfaces. These impacts can manifest over the short-term (acute) or over a significant part of the human lifespan (chronic).
Historically, the dangers of direct exposure have been tragically evident. The Great London Smog of 1952 (Laskin, 2006), for instance, was an acute event where high concentrations of particulates and sulphur dioxide led to an estimated 12,000 extra deaths. Chronic exposure cases include the residents of Minamata, Japan, who suffered severe neurological damage from consuming seafood contaminated with methylmercury from factory emissions (James et al., 2020). More recently, the decommissioning of a steel works in Corby, UK, is thought to have resulted in a cluster of birth defects linked to metal emissions. The 1984 leak of methyl isocyanate in Bhopal, India (Broughton, 2005), stands as a devastating example of acute exposure, causing the death of 22,000 people and long-term health issues for hundreds of thousands more.
Today, major contributors to direct mortality include exposure to ambient and indoor air pollution (particulates and ozone) and toxic chemicals (Fuller et al., 2022). The primary chemical drivers are metals and metalloids (like Lead, Mercury, Cadmium, and Arsenic), various organic compounds (such as benzene and dioxins), asbestos, and fluoride (WHO, 2025; Naidu et al., 2021).
Indirect Effects on Health and Well-being
Chemical pollution also harms humans through indirect effects, where the pollutant first impacts the ecosystem, creating a chain reaction that ultimately affects human populations.
One critical example is the contribution of antibiotic pollution in the environment to the antimicrobial resistance (AMR) crisis. This pollution is thought to accelerate the evolution of resistant pathogens, making infections harder to treat and resulting in an additional 1.2 million global deaths in 2019 (Cunningham et al., 2019), a number forecast to rise drastically. This topic is discussed in more detail later on in the module
Another striking illustration is the case of the drug diclofenac in South Asia. Used to treat cattle, the drug poisoned the vultures that scavenged on the carcasses, causing a massive population collapse. The subsequent increase in the feral dog population—many of which carried rabies—led to a rise in human rabies cases. It is estimated that the ecological disruption caused by this one chemical resulted in 500,000 extra human deaths (Frank and Sudarshan, 2022). Beyond direct mortality, the loss of vultures impacted human well-being by disrupting cultural practices, tourism, and local industries (Markandya et al., 2008).
The Global Burden of Pollution
Overall, pollution currently causes an estimated 9 million deaths annually worldwide, a figure that exceeds the combined mortality from AIDS/HIV, malnutrition, drug abuse, and road traffic accidents (Fuller et al., 2022). Around 90% of these deaths occur in Low- and Middle-Income Countries (LMICs), and deaths from modern pollution forms have increased by 66% over the past two decades. The actual burden is likely underestimated due to many unknowns regarding the precise occurrence and toxicological effects of numerous chemicals in the environment.
Recorded Lecture
Alistair Boxall gives an overview of the how chemicals in the environment can affect human health and wellbeing.
Key Reading Materials
Fuller, R., et al. (2022). Pollution and Health: A Progress Update. The Lancet Planetary Health, 6(11), e863–e874. https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(22)00090-0/fulltext
Naidu, R., et al. (2021). Chemical pollution and human health: a growing global concern. Nature Sustainability, 4(11), 933–942. https://doi.org/10.1016/j.envint.2021.106616
WHO (2020) Ten Chemicals of Public Health Concern. Available at: https://www.who.int/news-room/photo-story/detail/10-chemicals-of-public-health-concern (accessed October 2025)
Other Useful Reading Materials
Broughton, E. (2005). The Bhopal disaster and its aftermath: a review. Environmental Health: A Global Access Science Source, 4(1), 1–6. https://ehjournal.biomedcentral.com/articles/10.1186/1476-069X-4-6
Cunningham, C.J.L, et al. (2019). Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis. Lancet 399(10325):629 - 655. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)02724-0/fulltext?uid=7a06dafa-b036-b649-db43-73fd5692a143
Frank, D., and Sudarshan, K. (2022). The Social Costs of Keystone Species Collapse: Evidence from the Decline of Vultures in India. American Economic Review 114(10):3007–40. https://www.aeaweb.org/articles?id=10.1257/aer.20230016
James, A. K.; Nehzati, S.; Dolgova, N. V.; Sokaras, D.; Kroll, T.; Eto, K.; O’Donoghue, J. L.; Watson, G. E.; Myers, G. J.; Krone, P. H.; Pickering, I. J.; George, G. N. (2020) Rethinking the Minamata Tragedy: What Mercury Species Was Really Responsible?. Environ. Sci. Technol. 54, 2726– 2733. https://doi.org/10.1021/acs.est.9b06253
Laskin, D. (2006) The Great London Smog, Weatherwise, 59:6, 42-45. https://doi.org/10.3200/WEWI.59.6.42-45
Markandya, A., et al. (2008). Counting the cost of vulture decline—An appraisal of the human health and other benefits of vultures in India. Ecological Economics, 67(2), 177–184. https://doi.org/10.1016/j.ecolecon.2008.04.020
Netflix. (2025). Toxic Town [Television Series]. available at: https://www.netflix.com/gb/title/81372304