Main messages c Urinary 1-hydroxypyrene and malondialdehyde levels in Chinese restaurant workers reflect occupational exposure to polycyclic aromatic hydrocarbons from cooking oil fumes and oxidative stress. c Kitchen staff experience high exposure to cooking oil fumes in Chinese restaurants. Policy implications c Exposure to cooking oil fumes should be monitored in Chinese restaurants. c Further surveys should be undertaken in Chinese restaurants to examine the relationship between exposure to cooking oil fumes and disease. c Work place exposure to cooking oil fumes should be minimised. they realise the hazards of COFs as a result of having attended government training programs. On the other hand, home cooking for a few minutes versus cooking in a restaurant for hours may be another reason why home cooking is not a significant predictor for COF exposure. The likelihood of second-hand smoke exposure at work is small because all 19 surveyed restaurants were non-smoking areas, including both the kitchen and dining areas. Thus, restaurant workers who smoked usually did so outdoors or in designated smoking areas. Second-hand smoke exposure did not significantly influence urinary 1-OHP levels because our definition tended to over- estimate workers’ second-hand smoke exposure. This finding agrees with a previous study on urinary 1-OHP in police officers.27 This study also found, using MDA as an indicator, that oxidative stress in restaurant workers is positively associated with urinary 1-OHP levels and work hours per day. Thus, urinary 1-OHP was a good exposure biomarker for urinary MDA or oxidative stress. One limitation of this study was the lack of PAH exposure data for non-occupational settings, such as from vehicle traffic emissions. However, each day the restaurant workers spent more than 10 h in the restaurants, including work and rest periods, compared to less than 1 h in traffic. Therefore, the contribution of traffic sources to the PAH exposure of restaurant workers is believed to be small. Another limitation of this study is the lack of information regarding individual susceptibility to COF exposure in our subjects, which we believe could bias our work. Regardless of this limitation, this study concluded that 1-OHP was a good predictor of urinary MDA in male workers in Chinese restaurants. CONCLUSIONS The study findings indicate that urinary 1-OHP and MDA reflect occupational exposure to PAHs from COFs and oxidative stress in male workers in Chinese restaurants. O r ig in al a rt i cl e Funding: We are grateful for funding from the Institute of Occupational Safety and Health, Council of Labor Affairs, Taiwan (grant number: IOSH95-M304). Competing interests: None. 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