Associations of lifetime exposure to fine particulate matter (PM) and its constituents with increased risk and earlier occurrence of 14 site-specific cancers.

[BACKGROUND] Evidence is limited concerning whether and to what extent fine particulate matter pollution (particulate matter with an aerodynamic diameter less than 2.5 μm [PM]) is linked to the risk and the time to occurrence of site-specific cancers along with the key constituents of PM and the sensitive exposure window.

[METHODS] By using data from 277,446 participants in the UK Biobank, the authors estimated exposures to PM and its 15 constituents during each participant's lifetime and at different life stages using a bilinear interpolation method. The incidence and time to occurrence of 14 cancers were ascertained. Cox proportional hazard models and accelerated failure time models were applied to investigate the associations between air pollutants and incidence risk and occurrence time of 14 cancers.

[RESULTS] During a mean follow-up of 11.15 years, 25,820 patients with incident cancer were identified. Lifetime exposure to PM and to its constituents was associated with an increased incidence risk of 12 of 14 cancers, with hazard ratios and 95% confidence intervals ranging from 1.04 (95% confidence interval, 1.01-1.07) for breast cancer to 1.18 (95% confidence interval, 1.10-1.27) for esophageal cancer. The constituents chloride ion, ammonium, nitrate, and sodium demonstrated the most pronounced effects. The middle-aged and elderly life stage (individuals aged 45 years and older) comprised the sensitive exposure window. The time to occurrence of cancers was earlier by from 0.05 years (ovarian cancer) to 1.95 years (esophageal cancer) because of overexposure to PM levels greater than 5 μg/m.

[CONCLUSIONS] Lifetime exposure to PM and its constituents might increase the risk and accelerate the onset of various cancers. Combustion-sourced and agriculture-sourced components mainly account for this influence, with the middle-aged and elderly life stage (aged 45 years and older) a sensitive exposure window.