Ambient Air Pollution and Cancer Mortality in the Cancer Prevention Study II.

BACKGROUND: The International Agency for Research on Cancer classified both outdoor air pollution and airborne particulate matter as carcinogenic to humans (Group 1) for lung cancer. There may be associations with cancer at other sites; however, the epidemiological evidence is limited.

OBJECTIVE: The aim of this study was to clarify whether ambient air pollution is associated with specific types of cancer other than lung cancer by examining associations of ambient air pollution with nonlung cancer death in the Cancer Prevention Study II (CPS-II).

METHODS: Analysis included 623,048 CPS-II participants who were followed for 22 y (1982-2004). Modeled estimates of particulate matter with aerodynamic diameter <2.5µm (PM2.5 ) (1999-2004), nitrogen dioxide (NO2 ) (2006), and ozone (O3 ) (2002-2004) concentrations were linked to the participant residence at enrollment. Cox proportional hazards models were used to estimate associations per each fifth percentile-mean increment with cancer mortality at 29 anatomic sites, adjusted for individual and ecological covariates.

RESULTS: We observed 43,320 nonlung cancer deaths. PM2.5 was significantly positively associated with death from cancers of the kidney {adjusted hazard ratio (HR) per 4.4 μg/m3 =1.14 [95% confidence interval (CI): 1.03, 1.27]} and bladder [HR=1.13 (95% CI: 1.03, 1.23)]. NO2 was positively associated with colorectal cancer mortality [HR per 6.5 ppb=1.06 (95% CI: 1.02, 1.10). The results were similar in two-pollutant models including PM2.5 and NO2 and in three-pollutant models with O3 . We observed no statistically significant positive associations with death from other types of cancer based on results from adjusted models.

CONCLUSIONS: The results from this large prospective study suggest that ambient air pollution was not associated with death from most nonlung cancers, but associations with kidney, bladder, and colorectal cancer death warrant further investigation. https://doi.org/10.1289/EHP1249.