Long-term association of air pollution and incidence of lung cancer among older Americans: A national study in the Medicare cohort

• Type of Material: Article
• Authors: Cristina Su Liu, Harvard University; Yaguang Wei, Harvard University; Mahdieh Danesh Yazdi, Harvard University; Xinye Qiu, Harvard University; Edgar Castro, Harvard University; Qiao Zhu, Emory University; Longxiang Li, Harvard University; Petros Koutrakis, Harvard University; Christine Ekenga, Emory University; Liuhua Shi, Emory University; Joel D. Schwartz, Harvard University
• Language: English
• Date: 2023-10-14
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2023 The Author(s). Published by Elsevier Ltd.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): https://doi.org/10.1016/j.envint.2023.108266
• Title of Journal or Parent Work: Environment International
• Volume: 181
• Start Page: 108266
• Grant/Funding Information: This study was supported by National Institutes of Health (NIH) (grant number R01 ES032418 received by JS, R01 AG074357 received by LS, R21 ES032606 received by LS, P30 ES000002 by YW).
• Keywords: Medicare; Air pollution; Lung cancer; Incidence
• Research Categories: Environmental Sciences; Health Sciences, Public Health; Health Sciences, Epidemiology

Abstract

Background: Despite strong evidence of the association of fine particulate matter (PM2.5) exposure with an increased risk of lung cancer mortality, few studies had investigated associations of multiple pollutants simultaneously, or with incidence, or using causal methods. Disparities were also understudied. Objectives: We investigated long-term effects of PM2.5, nitrogen dioxide (NO2), warm-season ozone, and particle radioactivity (PR) exposures on lung cancer incidence in a nationwide cohort. Methods: We conducted a cohort study with Medicare beneficiaries (aged ≥ 65 years) continuously enrolled in the fee-for-service program in the contiguous US from 2001 to 2016. Air pollution exposure was averaged across three years and assigned based on ZIP code of residence. We fitted Cox proportional hazards models to estimate the hazard ratio (HR) for lung cancer incidence, adjusted for individual- and neighborhood-level confounders. As a sensitivity analysis, we evaluated the causal relationships using inverse probability weights. We further assessed effect modifications by individual- and neighborhood-level covariates. Results: We identified 166,860 lung cancer cases of 12,429,951 studied beneficiaries. In the multi-pollutant model, PM2.5 and NO2 exposures were statistically significantly associated with increased lung cancer incidence, while PR was marginally significantly associated. Specifically, the HR was 1.008 (95% confidence interval [CI]: 1.005, 1.011) per 1-μg/m3 increase in PM2.5, 1.013 (95% CI: 1.012, 1.013) per 1-ppb increase in NO2, and 1.005 (0.999, 1.012) per 1-mBq/m3 increase in PR. At low exposure levels, all pollutants were associated with increased lung cancer incidence. Men, older individuals, Blacks, and residents of low-income neighborhoods experienced larger effects of PM2.5 and PR. Discussion: Long-term PM2.5, NO2, and PR exposures were independently associated with increased lung cancer incidence among the national elderly population. Low-exposure analysis indicated that current national standards for PM2.5 and NO2 were not restrictive enough to protect public health, underscoring the need for more stringent air quality regulations.