Researchers say cooking fumes contain carcinogens

NTNU researchers have now documented what has long been suspected: The fumes from normal cooking contain both tars and high amounts of chemical compounds called aldehydes.

Posted by Synnøve Ressem

Hazardous fumes

Avoid the cooking fumes from your frying pan, especially if the ventilation is poor.

Your Saturday night steak might not taste quite so good after you read this article. Or you might think more carefully about how you prepare it – and perhaps consider replacing your ventilation fan.

NTNU researchers have now documented what has long been suspected: The fumes from normal cooking contain both tars and high amounts of chemical compounds called aldehydes. Both can cause cancer.

Ultrafine misery

The study included older ventilators (from the 1990s) and newer models mounted on the wall, along with modern approaches, where the ventilation hood is over a kitchen island, and the fan contains a charcoal filter.

The results were unambiguous. “We don’t recommend the fans fitted with carbon filters, because they absorb only large particles and spew the small ones back. The results were better when the fans vented directly to the outside, and the best results came when the fans were placed between two walls, between two cupboards or up to a corner.

This helped to increase suction. It is also very important to let the fan run for fifteen minutes after you’re done cooking,” say project manager Kristin Svendsen and PhD candidate Ann Kristin Sjaastad.

The measurements registered ultrafine particles down to 0.1 microns. These ultrafine particles are suspected of being particularly harmful to the lungs. The smaller they are, the easier and deeper they can be taken into the lung tissue.

The researchers were surprised to discover how fast the filters clogged. The filters showed obvious changes after just two kilograms of meat had been cooked.

Old fat, bad fat

Tests of the frying fat also showed surprising results. Margarine was compared with different types of cooking oil. In the first tests, margarine produced the worst fumes. Subsequent experiments showed the worst fumes came from oil.

“It appears that there is a correlation between the freshness (of the cooking fat) and the amount of hazardous substances in the fumes,” say Sjaastad and Svendsen.

The researchers took as their starting point normal cooking habits in private households. Both Sjaastad and Svendsen have changed their approach to cooking as a result. They fry food as little as possible. And they clean the filter in their exhaust hoods more often now. Much more often.

Synnøve Ressem works as a science journalist at GEMINI magazine, and has been a journalist for 23 years. She is employeed by the Norwegian University of Science and Technology in Trondheim.

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