Traffic-Related Air Pollution and Lung Cancer Incidence: The California Multiethnic Cohort Study


Background: While the contribution of air pollution to lung cancer risk is well characterized, few studies have been conducted in racially/ethnically and socioeconomically diverse populations. Methods: Among 97,288 California participants of the Multiethnic Cohort Study, we used Cox proportional hazards regression to examine associations between time-varying traffic-related air pollutants (gaseous and particulate matter (PM) pollutants and regional benzene) and lung cancer risk (n=2,796 cases; average follow-up=17 years), adjusting for demographics, lifetime smoking, occupation, neighborhood socioeconomic status (nSES), and lifestyle factors. Subgroup analyses were conducted for race/ethnicity, nSES, and other factors. Results: Among all participants, lung cancer risk was positively associated with nitrogen oxide (hazard ratio (HR)=1.15 per 50 ppb; 95% CI: 0.99-1.33), nitrogen dioxide (HR=1.12 per 20 ppb; 95% CI: 0.95-1.32), PM2.5 (HR=1.20 per 10 µg/m3; 95% CI: 1.01-1.43), carbon monoxide (HR=1.29 per 1000 ppb; 95% CI: 0.99-1.67) and regional benzene (HR=1.17 per 1 ppb; 95% CI: 1.02-1.34) exposures. These patterns of association were driven by associations among African American and Latino American groups. There was no formal evidence for heterogeneity of effects by nSES (p heterogeneity>0.31); although participants residing in low SES neighborhoods had increased lung cancer risk associated with nitrogen oxides and no association was observed among those in high SES neighborhoods. Conclusion: These findings in a large multiethnic population reflect an association between lung cancer and the mixture of traffic-related air pollution, and not a particular individual pollutant. They are consistent with the adverse effects of air pollution that have been described in less racially/ethnically and socioeconomically diverse populations. Our results also suggest an increased risk of lung cancer among those residing in low SES neighborhoods.

Authors: Iona Cheng, Juan Yang, Chiuchen Tseng, Jun Wu, Salma Shariff-Marco, Sung-Shim Lani Park, Shannon M Conroy, Pushkar P Inamdar, Scott Fruin, Timothy Larson, Veronica W Setiawan, Mindy C DeRouen, Scarlett Lin Gomez, Lynne R Wilkens, Loïc Le Marchand, Daniel O Stram, Jonathan Samet, Beate Ritz, Anna H Wu
; Full Source: American journal of respiratory and critical care medicine 2022 Jun 1. doi: 10.1164/rccm.202107-1770OC.