A systematic review of observational studies on long-term air pollution exposure and epigenetic alterations in adults.

Background: Evidence suggests that environmental exposures induce epigenetic modifications that can have long-lasting effects on multiple health outcomes, and an in-depth review of the epidemiological evidence is urgent. We aimed to comprehensively assess the associations between long-term exposure to air pollution and epigenetic changes in adults. Methods: We systematically searched EMBASE, MEDLINE, and Web of Science databases for relevant articles published in English from inception through 17 November 2023. We assessed and narratively synthesised eligible studies on ambient (i.e. non-occupational) and epigenetic alterations in adults. We separately documented relevant occupational studies identified by the search. Results: We analysed 52 eligible articles, including 30 ambient air pollution and 22 occupational air pollution exposure studies. Long-term exposure to ambient particulate matter (PM) with aerodynamic diameters of ≤2.5 μm (PM Conclusions: We demonstrated that long-term exposure to air pollution is associated with locus-specific methylation changes and histone modification in adults. Further elucidation of these epigenetic changes through epidemiological and laboratory work could provide new avenues to identify potential biomarkers linked to air pollutant exposure and to clarify their impacts on health outcomes. Registration: PROSPERO: CRD42023480771.