Dose-response relationship between cooking fumes exposures and lung cancer among Chinese nonsmoking women

The high incidence of lung cancer among Chinese females, despite a low smoking prevalence, remains poorly explained. Cooking fume exposure during frying could be an important risk factor. We carried out a population-based case-control study in Hong Kong. Cases were Chinese female nonsmokers with newly diagnosed primary lung cancer. Controls were female nonsmokers randomly sampled from the community, frequency matched by age groups. Face-to-face interviews were conducted using a standardized questionnaire. The "total cooking dish-years," categorized by increments of 50, was used as a surrogate of cooking fumes exposure. Multiple unconditional logistic regression was used to estimate the odds ratios (OR) for different levels of exposure after adjusting for various potential confounding factors. We interviewed 200 cases and 285 controls. The ORs of lung cancer across increasing levels of cooking dish-years were 1, 1.17, 1.92, 2.26, and 6.15. After adjusting for age and other potential confounding factors, the increasing trend of ORs with increasing exposure categories became clearer, being 1, 1.31, 4.12, 4.68, and 34. The OR of lung cancer was highest for deep-frying (2.56 per 10 dish-years) followed by that of frying (1.47), and stir-frying had the lowest OR (1.12) among the three methods. Cumulative exposure to cooking by means of any form of frying could increase the risk of lung cancer in Hong Kong nonsmoking women. Practical means to reduce exposures to cooking fumes should be given top priority in future research.