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Frying and Cooking Fumes

One wouldn’t expect that frying a steak exposes the cook to the same chemical that is used in mothballs, but it does. Researchers at the Norwegian University of Science and Technology were interested in exploring the potential risk of exposure to cooking fumes because previous work had established that heating meat to high temperatures results in the formation of compounds capable of causing cancer in test animals, and possibly in humans.

One wouldn’t expect that frying a steak exposes the cook to the same chemical that is used in mothballs, but it does. Researchers at the Norwegian University of Science and Technology were interested in exploring the potential risk of exposure to cooking fumes because previous work had established that heating meat to high temperatures results in the formation of compounds capable of causing cancer in test animals, and possibly in humans. For example, Taiwanese women experience a high rate of lung cancer even though only ten percent of them smoke. But a study has shown that the longer women spent cooking food, the higher their risk of lung cancer. Women who waited until the oil was very hot before cooking the food increased their risk compared with those who cooked at a lower temperature. Lung cancer rate is also high among Chinese chefs who cook in a wok, often in a confined space. The Norwegian researchers sought to study this risk further by fitting cooks with a gas collecting tube on their shoulder as they pan fried steaks either in margarine or soya oil for fifteen minutes, repeating the procedure five times in a row with twenty five minute breaks in between. This scenario approximated that in a restaurant kitchen. Of particular interest were polycyclic aromatic hydrocarbons, or PAHs, since these are established animal carcinogens. Napthalene, a compound that for commercial purposes is isolated from coal tar, belongs to this category, and in fact was the only PAH detected. Of course the presence of naphthalene means nothing unless the amount detected is compared with known safety standards. Such standards have been established because naphthalene has long been used to repel moths, although it has now mostly been replaced by 1,4-dichlorobenzene. The amount of naphthalene detected was less than one one hundredth of the Norwegian environmental exposure limit, but that did not stop newspapers from flashing headlines such as “frying steak may increase your risk of cancer.” The study did not show anything like that. First of all, the study involved exposure to fumes in a commercial environment, not a home kitchen. Furthermore, there was no investigation of health effects at all, just of amounts of chemicals in the air, which turned out to be way less than acceptable standards, although more were formed when cooking on a gas rather than an electric stove. Chances are that frying steaks will not even keep moths away, never mind causing an inhalation problem for cooks, at least as far as PAHs are concerned.

Inhalation of tiny bits of particulate matter generated by frying may be a different story, and there is also the possibility that some aldehydes detected by the Norwegian scientists may have a mutagenic effect. It should also be mentioned that the researchers did not study the polycyclic aromatic hydrocarbon content of the steak itself, which would be a more relevant experiment. Eating the steak is undoubtedly more risky than cooking it. I guess one could make an argument for steak tartare, in which case you don’t have to worry about compounds like naphthalene being present, only about bacteria making you sick.

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