Shields P G, Xu G X, Blot W J, Fraumeni J F, Trivers G E, Pellizzari E D, Qu Y H, Gao Y T, Harris C C
Laboratory of Human Carcinogenesis, National Cancer Institute, Bethesda, Md 20892, USA.
J Natl Cancer Inst. 1995 Jun 7;87(11):836-41. doi: 10.1093/jnci/87.11.836.
The lung cancer incidence in Chinese women is among the highest in the world, but tobacco smoking accounts for only a minority of the cancers. Epidemiologic investigations of lung cancer among Chinese women have implicated exposure to indoor air pollution from wok cooking, where the volatile emissions from unrefined cooking oils are mutagenic.
This study was conducted to identify and quantify the potentially mutagenic substances emitted from a variety of cooking oils heated to the temperatures typically used in wok cooking.
Several cooking oils and fatty acids were heated in a wok to boiling, at temperatures (for the cooking oils) that ranged from 240 degrees C to 280 degrees C (typical cooking temperatures in Shanghai, China). The oils tested were unrefined Chinese rapeseed, refined U.S. rapeseed (known as canola), Chinese soybean, and Chinese peanut in addition to linolenic, linoleic, and erucic fatty acids. Condensates of the emissions were collected and tested in the Salmonella mutation assay (using Salmonella typhimurium tester strains TA98 and TA104). Volatile decomposition products also were subjected to gas chromatography and mass spectroscopy. Aldehydes were detected using high-performance liquid chromatography and UV spectroscopy.
1,3-Butadiene, benzene, acrolein, formaldehyde, and other related compounds were qualitatively and quantitatively detected, with emissions tending to be highest for unrefined Chinese rapeseed oil and lowest for peanut oil. The emission of 1,3-butadiene and benzene was approximately 22-fold and 12-fold higher, respectively, from heated unrefined Chinese rapeseed oil than from heated peanut oil. Lowering the cooking temperatures or adding an antioxidant, such as butylated hydroxyanisole, before cooking decreased the amount of these volatile emissions. Among the individual fatty acids tested, heated linolenic acid produced the greatest quantities of 1,3-butadiene, benzene, and acrolein. Separately, the mutagenicity of individual volatile emission condensates was correlated with linolenic acid content (r = .83; P = .0004). Condensates from heated linolenic acid, but not linoleic or erucic acid, were highly mutagenic.
These studies, combined with experimental and epidemiologic findings, suggest that high-temperature wok cooking with unrefined Chinese rapeseed oil may increase lung cancer risk. This study indicates methods that may reduce that risk.
The common use of wok cooking in China might be an important but controllable risk factor in the etiology of lung cancer. In the United States, where cooking oils are usually refined for purity, additional studies should be conducted to further quantify the potential risks of such methods of cooking.
中国女性肺癌发病率位居世界前列，但吸烟导致的肺癌仅占少数。针对中国女性肺癌的流行病学调查表明，中式烹饪产生的室内空气污染与肺癌发病有关，其中未精炼食用油的挥发性排放物具有致突变性。
本研究旨在识别并量化多种食用油在中式烹饪常用温度下加热时释放的潜在致突变物质。
在中式炒锅中将几种食用油和脂肪酸加热至沸腾，烹饪油的加热温度范围为240摄氏度至280摄氏度（中国上海的典型烹饪温度）。所测试的油包括未精炼的中国菜籽油、精炼的美国菜籽油（即加拿大油菜籽）、中国大豆油和中国花生油，此外还有亚麻酸、亚油酸和芥酸。收集排放物的冷凝物，并在沙门氏菌突变试验中进行测试（使用鼠伤寒沙门氏菌测试菌株TA98和TA104）。挥发性分解产物也进行了气相色谱和质谱分析。使用高效液相色谱和紫外光谱检测醛类物质。
定性和定量检测到了1,3 - 丁二烯、苯、丙烯醛、甲醛及其他相关化合物排放，未精炼的中国菜籽油排放往往最高，花生油排放最低。加热未精炼的中国菜籽油产生的1,3 - 丁二烯和苯排放量分别比加热花生油高出约22倍和12倍。降低烹饪温度或在烹饪前添加抗氧化剂（如丁基羟基茴香醚）可减少这些挥发性排放物的量。在所测试的单个脂肪酸中，加热亚麻酸产生的1,3 - 丁二烯、苯和丙烯醛量最多。单独来看，单个挥发性排放冷凝物的致突变性与亚麻酸含量相关（r = 0.83；P = 0.0004）。加热亚麻酸产生的冷凝物具有高度致突变性，而亚油酸或芥酸产生的冷凝物则不然。
这些研究结合实验和流行病学研究结果表明，使用未精炼的中国菜籽油进行高温中式烹饪可能会增加肺癌风险。本研究指出了可能降低该风险的方法。
在中国，中式烹饪的普遍使用可能是肺癌病因中一个重要但可控的风险因素。在美国，食用油通常经过精炼以保证纯度，应开展更多研究以进一步量化此类烹饪方法的潜在风险。
