Frying linked to dangerous fumes
Frequent cooking using frying methods could lead to increased exposure to potential cancer-causing chemicals,according to a new study
While cigarette smoking remains the primary cause of lung cancer, the disease is unusually common among female non-smokers in Southeastern Asia, including the Chinese population in Singapore. Professor Koh Woon Puay from the Saw Swee Hock School of Public Health (SSHSPH) and the Duke-NUS Graduate Medical School, together with a team of US investigators, recently published a study looking into the phenomenon and its relation to cooking.
One hypothesis is that fumes generated from Chinese-style cooking, typically frying with a wok, may be a risk factor for lung cancer. The heated oil used in wok cooking, including the common techniques of stir frying and deep frying meat, produces vapours which contain a variety of potentially mutagenic and carcinogenic compounds. Women do most of the cooking in traditional Chinese households, including in Singapore. Examining this hypothesis, the study found that Singapore Chinese women who regularly cooked at home displayed elevated levels of potential toxicants and carcinogens in their urine, indicating a possible exposure to such substances found in fumes produced during cooking.
Prof Koh and her team gathered data and analysed urine samples from 328 Singaporean Chinese women, who were lifetime non-smokers, over a period of two years. These women, who did varying amounts of cooking, were each asked to answer questions related to their cooking habits and other factors. About 79 per cent used frying methods only and 13 per cent used frying methods along with other non-frying methods.
The results showed that there were higher levels of potential cancer-causing agents in the urine of women who cooked at home more than five times a week compared to those who did not cook. This study thus provided indirect evidence for an increased exposure to potential lung cancer-causing agents in the cooking fumes among women who cooked regularly.
The research builds on an earlier study in 2010 which found higher levels of urinary mercapturic acid metabolites of benzene, acrolein and crotonaldehyde in Chinese women who regularly cooked at home using a wok. It is also a follow-up to previous studies showing the presence of these compounds in the fumes released during high temperature cooking, including common methods of stir frying, pan frying and deep frying.
Such potential cancer-causing substances in the cooking fumes may alter DNA and cause mutations which could lead to cancer. For non-smokers, lung cancer is often only detected at the advanced stages as it is a diagnosis that many would not have expected.
Although any direct causal relationship with cancer has yet to be determined, Prof Koh advised taking precautionary measures. "The present study, together with our past epidemiologic studies, demonstrates the need for preventive measures such as improving ventilation or using an exhaust hood to reduce exposure to cooking fumes from frying, said Prof Koh.
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