Lung Cancer and Indoor Exposure of Unvented Coal and Wood Combustion Emissions in Xuan Wei, China

摘要

Residents of Xuan Wei County in China have unusually high lung cancer mortality that cannot be attributed to tobacco use or occupational exposure. They are exposed to smoke from unvented, open pit coal or wood fires (often used for cooking and heating). The variation in lung cancer rates among communes within the county suggests that indoor combustion of smoky coal may be the prime determinant of lung cancer. To characterize the air in Xuan Wei homes, samples of the air particles and semivolatile organics were collected from homes located in communes with different lung cancer rates. Samples collected in the commune in which the lung cancer rate is high and smoky coal is the predominant fuel contained high concentrations of submicron particles with high organic content; organic extracts of these samples were mutagenic. Samples from homes in a wood-burning commune, which has a low lung cancer rate, consisted mostly of larger particles of lower organic content and mutagenicity. The smoky coal sample was also a more potent skin tumor initiator compared to the wood or smokeless coal sample and was a mouse skin carcinogen.