Background
The intersection of global climate change and chemical pollution represents a threat to public health. As discussed in Module 1 of this online primer, it is already estimated that pollution contributes to approximately 9 million deaths globally each year with chemical pollution a significant contributor to this number (Fuller et al., 2022). An even greater number of people will suffer from sublethal impacts of chemical pollution on human health, including cardiovascular disease, diabetes, developmental effects, cancers, reproductive effects and neurological effects. These figures likely underestimate the true scale of the problem. Climate change and other global megatrends are likely to influence the use, exposure and risks of
The Exposure Landscape
Temperature increases, changes in precipitation patterns and the increase in extreme events results from climate change is expected to influence human exposure to chemicals. Climate change is expected to alter chemical use, use patterns and emissions to the environment (Balbus et al., 2012). Rising global temperatures increase the volatilization of chemicals like methane, ammonia, and pesticides into the air, while increased solubility can mobilize heavy metals and persistent organic pollutants (HSA, 2023). Extreme weather events further like floods and heavy precipitation will lead to the remobilization and leaching of contaminants from waste dumps and agricultural land into groundwater and drinking water supplies. Additionally, wildfires and landfill fires triggered by extreme heat will release a mix of chemicals into the atmosphere (HSA, 2023). Sea-level rise and coastal erosion also threaten to flood low-lying hazardous waste sites, introducing industrial chemicals into coastal environments (Brandt et al., 2018).
Biological Vulnerability and Toxicity
Environmental changes resulting from climate change will also alter human vulnerability and chemical toxicity itself. For example, changes in temperature will alter the absorption, metabolism and excretion of chemicals into the human body (Noyes et al., 2009). Changes in UV exposure might enhance the toxicity of polycyclic hydrocarbons to humans (Weistenhofer et al., 2022). The combination of exposure to air pollutants (including particulates, NOx and ozone) with heat stress can exacerbate cardiovascular and respiratory diseases (Areal et al., 2022).
The Broader Megatrend Context
The interaction of chemicals and climate does not exist in isolation and the risks of chemical pollutants will also be influenced by several other global megatrends. The European Commission identify 14 global megatrends, including climate change (European Commission, 2026). These will also influence the risks of chemical pollution to human health. For instance, widening inequalities will mean that low-income communities are disproportionately located near industrial sites, facing higher cumulative exposures. Continuing urbanization can worsen air and water quality, while growing consumption and the changing nature of work (such as the shift to informal "gig" work) can bypass traditional chemical safety standards. Conversely, megatrends like accelerating technological change and new governing systems offer potential mitigation through improved monitoring of chemicals in the environment to support chemicals management, enhanced use of "sustainable by design" chemicals, improved treatment technologies to remove pollution, and the availability of more agile regulatory frameworks.
A Major Research Need
Moving forward, we must stop viewing chemical pollution as a static, isolated issue and instead recognize it as a dynamic risk that will be shaped by the different global megatrends. To truly protect human health, risk assessments must evolve to account for the synergistic pressures of climate change, shifting demographics, and rapid technological turnover on chemical exposure and toxicity. However, the intersection of these megatrends and toxicology remains a significantly under-researched frontier.
Alistair Boxall, who is Professor of Environmental Science at the University of York, talks about how climate change (and other global megatrends) will alter the exposure and impacts of chemical pollution on human health
Key Reading
Areal AT, Zhao Q, Wigmann C, Schneider A, Schikowski T. (2022) The effect of air pollution when modified by temperature on respiratory health outcomes: A systematic review and meta-analysis. Sci Total Environ. 811:152336. doi: 10.1016/j.scitotenv.2021.152336.
Balbus JM, Boxall AB, Fenske RA, McKone TE, Zeise L. (2013) Implications of global climate change for the assessment and management of human health risks of chemicals in the natural environment. Environ Toxicol Chem. 32(1):62-78. doi: 10.1002/etc.2046.
Brand JH, Spencer KL. (2020) Will flooding or erosion of historic landfills result in a significant release of soluble contaminants to the coastal zone? Sci Total Environ. 724:138150. doi: 10.1016/j.scitotenv.2020.138150.
European Commission (2026) Megatrends Hub.
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
UK Health Security Agency (2023) Health Effects of Climate Change (HECC) in the UK: 2023 report. Chapter 12. Impact of climate change on human exposure to chemicals in the UK
Weistenhöfer W, Lutz R, Hiller J, Schmitz-Spanke S, Drexler H. (2022) Syncarcinogenesis of natural UV radiation and polycyclic aromatic hydrocarbons in the development of squamous cell carcinomas of the skin? J Dtsch Dermatol Ges. 20(9):1179-1186. doi: 10.1111/ddg.14818.