Case-control study of lung cancer among sugar cane farmers in India

Objectives-To investigate the risk of lung cancer among sugar cane farmers and sugar mill workers. Methods-A case-control study was conducted based in six hospitals in the pr edominantly sugar cane farming districts of the province of Maharashtra in India. Newly diagnosed, histologically confirmed cases were identified from these hospitals between May 1996 and April 1998. Other cancers were chosen as controls and matched to cases by age, sex, district of residence, and t iming of diagnosis. Results-Adjusting for confounders, an increased risk of lung cancer was fou nd for workers ever employed on a sugar cane farm (odds ratio (OR) 1.92, 95 % confidence interval (95% CI) 1.08 to 3.40). Increased risks were found fo r work involving preparation of the farm (OR 1.81, 95% CI 0.99 to 3.27) and burning of the farm after harvesting (OR 1.82, 95% CI 0.99 to 3.34). Non-s ignificant increases in risks were found for harvesting the crop (OR 1.41, 95% CI 0.70 to 2.90) and processing the cane in the mills (OR 1.70, 95% CI 0.20 to 12.60). Conclusions-Exposure to fibres of biogenic amorphous silica (BAS) formed fr om silica absorbed from the soil and deposited in the leaves of the sugar c ane crop or crystalline silica formed as a result of conversion of BAS to c ristobalite at high temperatures may account for the increased risks of lun g cancer among sugar cane farmers.