Original article 1 Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan; 2 Department of Biomedical Laboratory Science, Kaohsiung Medical University, Kaohsiung, Taiwan; 3 Division of Environmental Health and Occupational Medicine, National Health Research Institute, Miaoli, Taiwan Correspondence to: Dr Chang-Chuan Chan, Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Rm 722, No 17, Xu-Zhou Road, Taipei, 10020 Taiwan; ccchan@ntu.edu.tw Accepted 29 February 2008 This paper is freely available online under the BMJ Journals unlocked scheme, see http:// oem.bmj.com/info/unlocked.dtl 732 Urinary 1-hydroxypyrene and malondialdehyde in male workers in Chinese restaurants C-H Pan,1 C-C Chan,1 Y-L Huang,2 K-Y Wu3 ABSTRACT Objectives: To assess internal dose and oxidative stress in male restaurant workers exposed to polycyclic aromatic hydrocarbons (PAHs) from cooking oil fumes (COFs) in Chinese restaurants. Methods: The study participants included 288 male restaurant workers (171 kitchen and 117 service staff) in Chinese restaurants in Taiwan. Airborne particulate PAHs were measured over 12 h on each of two consecutive work days and then identified using high performance liquid chromatography. Urinary 1-hydroxypyrene (1-OHP) measurements were used to indicate COF exposure, and urinary malondialdehyde (MDA) was adopted as an oxidative stress marker. Multiple regression models were used to assess the relationship between MDA and 1-OHP levels after adjusting for key personal covariates. Results: Summed particulate PAH levels in kitchens (median 23.9 ng/m3) were significantly higher than those in dining areas (median 4.9 ng/m3). For non-smoking kitchen staff, mean MDA and 1-OHP levels were 344.2 (SD 243.7) and 6.0 (SD 8.0) mmol/mol creatinine, respectively. These levels were significantly higher than those for non-smoking service staff, which were 244.2 (SD 164.4) and 2.4 (SD 4.3) mmol/mol creatinine, respectively. Urinary 1-OHP levels were significantly associated with work in kitchens (p,0.05). Furthermore, urinary MDA levels were significantly associated with urinary 1-OHP levels (p,0.001) and working hours per day (p,0.05). Conclusions: These findings indicate that urinary 1-OHP and MDA levels reflect occupational exposure to PAHs from COFs and oxidative stress in workers in Chinese restaurants. Cooking oil fumes (COFs) are created and released into the environment when food is fried, stir fried or grilled using cooking oil at high temperatures. The degradation of sugar and fat, and the pyrolysis of proteins and amino acids during high tempera- ture treatment of food can produce harmful degraded materials1 such as polycyclic aromatic hydrocarbons (PAHs),2 aromatic amines,3 nitro- polycyclic aromatic hydrocarbons,4 benzene5 and aldehydes.6 7 Traditional Chinese cooking makes frequent use of stir frying and deep frying which generate significant amounts of COFs.8 Because the adverse health effects of COFs are related to long-term exposure, a biological mon- itoring approach assessing the internal dose of an individual is the preferred approach for examining occupational exposure to COFs. One indicator of COF exposure for restaurant workers is the presence of metabolites of PAHs, such as 1- hydroxypyrene (1-OHP). Studies have identified urinary 1-OHP as a good biological marker of PAH exposure in fire-fighters,9 iron foundry workers10 and coke oven workers.11 12 This study investigates whether urinary 1-OHP and work in kitchens are good indicators of COF exposure in workers in Chinese restaurants. Increased induction of lipid peroxidation of lung epithelial cells and oxidative stress following exposure to COFs have been reported in an in vitro8 and a cross-sectional study,13 respectively. Notably, two studies conducted in Western coun- tries identified an increased risk of lung cancer in male restaurant cooks, even after adjusting for tobacco use.14 15 Oxidative stress is defined as a disequilibrium between pro-oxidant and anti-oxi- dant systems in intact cells resulting from oxygen- using metabolic reactions; the pro-oxidant and anti-oxidant systems continuously generate and detoxify oxidants during normal aerobic metabo- lism. Lipid peroxidation is a type of oxidative stress and can be defined as the oxidative deterioration of lipids containing carbon–carbon double bonds. Plasma malondialdehyde (MDA) is a biological marker of lipid peroxidation resulting from oxida- tive stress.16 Previous studies have demonstrated relationships between lipid peroxidation and ather- osclerosis,17 aging,18 rheumatoid arthritis,19 diabetes mellitus20 and cancer.21 Studies also demonstrated that MDA, a stable aldehydic product of lipid peroxidation contained in biological samples such as urine, hair or blood, can reflect global oxidative status in the human body.22 23 This study assesses internal dose using urinary 1-OHP and oxidative stress using urinary MDA in male restaurant workers exposed to PAHs from COFs in Chinese restaurants. METHODS Study subjects In 2005, 372 male restaurant workers employed for at least 1 year in 19 Chinese restaurants in Taiwan were contacted via two trade unions. A total of 288 restaurant workers who completed both a ques- tionnaire survey and a health check-up were then recruited (response rate 77%). The 85 non-partici- pating workers could not attend pre-arranged health check-ups owing to work commitments. Trained interviewers met the participants between July 2005 and December 2005 and using a questionnaire collected data on age, work experi- ence, main cooking methods used, height, weight, employment in kitchen work versus other restau- rant employment, health status and life style (including smoking, cooking at home, second-hand smoke exposure and use of respiratory protection devices). The variables smoking, cooking at home and second-hand smoke exposure were defined as Occup Environ Med 2008;65:732–735. doi:10.1136/oem.2007.036970