Methylated PAHs from Household Coal Use and Risk of Lung Cancer Among Never-Smoking Women in Xuanwei and Fuyuan, China

Background: Lung cancer rates for never-smoking women in Xuanwei and Fuyuan, China are among the highest in the world and have been attributed to use of “smoky” (bituminous) coal. However, the key carcinogenic components of coal that drive lung cancer risk here have not been identified. Methods: We conducted a population-based case-control study of lung cancer among 1015 never smoking female cases and 485 comparable controls and linked cancer risk through a multipollutant model to 43 household air pollution (HAP) chemicals and particulates measured in a comprehensive exposure study conducted in the same population. Exposures assessed included methylated polycyclic aromatic hydrocarbons (PAH), which have never been directly evaluated in an epidemiologic study of any cancer. Findings: The strongest detected risk of lung cancer was for 5-methylchrysene, a mutagenic and carcinogenic PAH. In contrast, neither benzo(a)pyrene, a standard marker of PAH exposure used in risk assessment, nor fine particulate matter (PM2.5), commonly used to evaluate health outcomes from outdoor air pollution, were associated with risk of lung cancer in multipollutant models. Interpretation: This is the first study to comprehensively evaluate lung cancer risk from HAP constituents estimated over the entire lifecourse. Given the global ubiquity of coal use domestically for indoor cooking and heating and commercially for electric power generation, our study suggests that more extensive monitoring of coal combustion products including methylated PAHs may be warranted to more accurately assess health risks and develop prevention strategies from this exposure. Funding Statement: Funding provided by the intramural research program of the National Cancer Institute. Declaration of Interests: Authors have no conflicts of interest to declare. Ethical Approval Statement: The study protocol was approved by the institutional review boards of the National Cancer Institute (NCI) and China National Environmental Monitoring Center.