Why cooking meat with gas raises the risk of cancer

15:17 18 February 2010

Chefs who cook meat on a gas hob are more likely to develop cancer, as opposed to ones who use electric, a Norwegian study has found.

Fumes given off when cooking at high temperatures have been shown to alter DNA in a way which could be linked to an increase the risk of lung cancer.

The International Agency for Research on Cancer recently classified high-temperature frying as 'probably carcinogenic to humans'. This rank is the same category as diesel and some insecticides.

The researchers stated that an increased risk of respiratory tract cancer in cooks and bakers has been reported as well as compounds found in the breathing zone of cooks when frying.

The study, which was published journal Occupational and Environmental Medicine, involved frying 17 beef steaks on a gas or electric hob consecutively for 15 minutes using margarine or soya bean oil.

The setting of the experiment was a specially built kitchen which was geared up to act like a commercial restaurant's, complete with extractors over the hob.

The study revealed that the levels of polycyclic aromatic hydrogcarbons produced during the experiments were below accepted occupational safety thresholds.

However, they noted that there were other particles found in the fumes for which there is no established safe level.

Ann Kristin Sjaastad, lead author from Norwegian University of Science and Technology, in Trondheim, wrote in the journal: "The measured levels of total particles and PAHs for the cooks in our study are far below the Norwegian occupational exposure limits for nuisance dust.

"However, cooking fumes consist of a mixture of toxic and mutagenic compounds, including mutagenic aldehydes and heterocyclic amines with no known dose-response relationship, so exposure to cooking fumes should be reduced as much as possible.

"Our study shows that using a gas stove instead of an electric stove results in higher levels of PAHs, aldehydes and particles.

"This is presumed to be due to the higher temperature of the gas flame resulting in more thermal degradation products. The higher level of ultrafine particles may also be due to the gas flame itself and not just a result of the cooking process."

Dr Deborah Jarvis, who works at the National Heart and Lung Institute and within the Medical Research Council and Health Protection Agency Centre for Environment and Health at Imperial College London, said: “There have been large scale studies to see whether people who cook with gas have more breathing problems - such as coughs, infections and asthma - than those who cook with electricity. Results from these studies are inconsistent.

"This new study may help us understand why these inconsistencies occur. The public health message to the general public remains the same – keep your kitchen well-ventilated when cooking, and make sure all your gas appliances are well maintained.”

Prof Roy Harrison, Professor of Environmental Health, Birmingham University, was less impressed: “There are no big surprises in this work. Cooking, and especially frying, have long been known to be a source of carcinogenic chemicals and ultrafine particles. The health consequences, if any, remain uncertain.”