Smoky coal, tobacco smoking, and lung cancer risk in Xuanwei, China.

Lung cancer rates in Xuanwei are the highest in China. In-home use of smoky coal has been associated with lung cancer risk, and the association of smoking and lung cancer risk strengthened after stove improvement. Here, we explored the differential association of tobacco use and lung cancer risk by the intensity, duration, and type of coal used. We conducted a population-based case-control study of 260 male lung cancer cases and 260 age-matched male controls. Odds ratios (OR) and 95% confidence interval (CI) for tobacco use was calculated by conditional logistic regression. Use of smoky coal was significantly associated with an increased risk of lung cancer, and tobacco use was weakly and non-significantly associated with lung cancer risk. When the association was assessed by coal use, the cigarette-lung cancer risk association was null in hazardous coal users and elevated in less hazardous smoky coal users and non-smoky coal users. The risk of lung cancer per cigarette per day decreased as annual use of coal increased (>0-3 tons: OR: 1.09; 95% CI: 1.03-1.17; >3 tons: OR: 0.99; 95% CI: 0.95-1.03). Among more hazardous coal users, attenuation occurred at even low levels of usage (>0-3 tons: OR: 1.02; 95% CI: 0.91-1.14; >3 tons: OR: 0.94; 95% CI: 0.97-1.03). We found evidence that smoky coal attenuated the tobacco and lung cancer risk association in males that lived in Xuanwei, particularly among users of hazardous coal where even low levels of smoky coal attenuated the association. Our results suggest that the adverse effects of tobacco may become more apparent as China's population continues to switch to cleaner fuels for the home, underscoring the urgent need for smoking cessation in China and elsewhere.

Kim C ，Chapman RS ，Hu W ，He X ，Hosgood HD ，Liu LZ ，Lai H ，Chen W ，Silverman DT ，Vermeulen R ，Tian L ，Bassig B ，Shen M ，Zhang Y ，Ma S ，Rothman N ，Lan Q ... -  《-》

[Molecular epidemiology study in Xuanwei: the relationship among 
coal type, genotype and lung cancer risk].

Li J ，He J ，Tang R ，Hu W ，Lan Q ，He X ，Li Y ，Zhang Y ... -  《-》

[Risk Factors of Lung Cancer in Xuanwei, Yunnan Province, China].

Liu L ，Wan X ，Chen G ，Ma X ，Ning B ，Yang G ... -  《-》

Lung cancer risk by geologic coal deposits: A case-control study of female never-smokers from Xuanwei and Fuyuan, China.

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.

Wong JYY ，Downward GS ，Hu W ，Portengen L ，Seow WJ ，Silverman DT ，Bassig BA ，Zhang J ，Xu J ，Ji BT ，Li J ，He J ，Yang K ，Tian L ，Shen M ，Huang Y ，Vermeulen R ，Rothman N ，Lan Q ... -  《-》

Variation in lung cancer risk by smoky coal subtype in Xuanwei, China.

Lung cancer rates in Xuanwei County have been among the highest in China for both males and females and have been causally associated with exposure to indoor smoky (bituminous) coal emissions that contain very high levels of polycyclic aromatic hydrocarbons. There are numerous coal mines across the County. Although lung cancer risk is strongly associated with the use of smoky coal as a whole, variation in risk by smoky coal subtype has not been characterized as yet. We conducted a population-based case-control study of 498 lung cancer cases and 498 controls, individually matched to case subjects on age (+/-2 years) and sex to examine risk by coal subtype. Odds ratios (ORs) and 95% confidence intervals (CIs) for coal subtype were calculated by conditional logistic regression, adjusting for potential confounders. Overall, smoky coal use was positively and statistically significantly associated with lung cancer risk, when compared with the use of smokeless coal or wood (OR = 7.7, 95% CI = 4.5-13.3). Furthermore, there was a marked heterogeneity in risk estimates for specific subtypes of smoky coal (test for heterogeneity: p = 5.17 x 10(-10)). Estimates were highest for coal of the Laibin (OR = 24.8, 95% CI = 12.4-49.6) and Longtan (OR = 11.6, 95% CI = 5.0-27.2) coal types and lower for coal from other subtypes. These findings strongly suggest that in Xuanwei and elsewhere, the carcinogenic potential of coal combustion products can exhibit substantial local variation by specific coal source.

Lan Q ，He X ，Shen M ，Tian L ，Liu LZ ，Lai H ，Chen W ，Berndt SI ，Hosgood HD ，Lee KM ，Zheng T ，Blair A ，Chapman RS ... -  《-》