Coal types vary around the world because of geochemical differences in their source deposits; however, the influence of
coal emissions from different deposits on human health remains unexplored. To address this issue, we conducted the first study of the relationship between
coal use from various deposits and
lung cancer risk in Xuanwei and
Fuyuan, counties in China where
lung cancer rates are among the highest in the world among female never-smokers due to use of bituminous ("smoky")
coal for heating and cooking. We conducted a population-based case-control study of 1031
lung cancer cases and 493 controls among never-smoking women in Xuanwei and
Fuyuan. Logistic regression models were used to estimate associations between
coal use from various deposits across the lifecourse and
lung cancer risk. There was substantial heterogeneity in risks by
coal deposit (p = 7.8E-05). Compared to non-smoky
coal users, risks by smoky
coal deposit ranged from OR = 7.49 (95% CI: 3.43-16.38) to OR = 33.40 (95% CI: 13.07-85.34). Further, women born into homes that used smoky
coal and subsequently changed to non-smoky
coal had a higher risk (OR = 10.83 (95% CI: 4.61-25.46)) than women born into homes that used non-smoky
coal and changed to smoky
coal (OR = 4.74 (95% CI: 2.03-11.04, pdifference = 0.04)). Our study demonstrates that various sources of
coal have considerably different impact on
lung cancer in this population and suggests that early-life exposure to carcinogenic emissions may exert substantial influence on health risks later in life. These factors should be considered when evaluating the health risks posed by exposure to
coal combustion emissions.