Risk factors for lung cancer in non-smokers in Xuanwei County of China.

Tobacco smoking and some types of occupational exposures have consistently been considered as important etiologic factors of lung cancer in industrial countries. At the First World Conference of Lung Cancer (Wyndwer, 1983), it was stressed that more attention should be paid to finding out the causes of lung cancer in non-smokers. In Xuanwei County, Yunnan Province, annual lung cancer death rate was 27.7 per 100,000 in males, among China's highest, and 25.3 per 100,000 in females, the China's highest. The female's lung cancer death rate in Xuanwei County was even much higher than that of the same period in USA white women (ECACM, 1979; Mulvihill, 1976). Marked district variation in cancer mortality exists within Xuanwei County. The county can be divided into high-, medium- and low-mortality areas. Over 90% of the population are farmers. The local residents traditionally burned three major kinds of fuels: "smoky" coal, "smokeless" coal and "wood", for heating and cooking. The three lung cancer high mortality areas, including "Chengguan", "Rongcheng" and "Laibin" communes, mainly burned the "smoky" coal from Laibin smoky-coal mine. The fuel was burned in a shallow, unventilated fire pit in the floor of the dwelling. Fuel burning in shallow unventilated pits has resulted in high indoor air pollution levels. The concentrations of airborne particles (pm 10) inside houses during smoky coal and wood combustion were very high. Indoor concentration of suspended particulates and dichloromethane extractable organics were 24.4mg/m3 and 17.6mg/m3 in burning of "smoky" coal; 22.3mg/m3, 12.3mg/m3 for burning wood; and 1.8mg/m3, 0.5mg/m3 for burning of smokeless coals.(ABSTRACT TRUNCATED AT 250 WORDS)