Carcinogenic Compound in Your Home. Even If You Don't Smoke

• Gas stoves emit benzene, a carcinogenic compound that spreads throughout the home, even outside the kitchen, increasing the risk of cancer
• A study using the CONTAM model showed that the highest exposure occurs with intensive cooking and lack of ventilation, especially in small apartments
• Effective preventive measures include the use of ventilation, high-efficiency hoods and switching to electric or induction cookers.

The transition from coal-fired heating to coal-based city gas was a major breakthrough at the beginning of the 20th century, not only in the lives of housewives. Coal and its combustion products were dirty, carbon monoxide poisoning occurred, and coal stoves and irons were difficult to use. Gas workers organized gas cooking demonstrations, gas-filled balloon flights, and other marketing activities. Promotional slogans such as "Illuminate with gas" or "Cook with gas" appeared.

Gas provided not only the energy needed for cooking or baking, but also for lighting, heating water in the bathroom, ironing, and even powering the refrigerator. Over time, "town gas", containing poisonous carbon monoxide, was replaced by more calorific natural gas. However, electricity replaced gas in most applications - the main ones that survived were cheaper to use than electric water heaters and gas cookers.

Over the years, more and more scientific studies have emerged indicating the harmfulness of gas combustion products:

• benzene,
• formaldehyde,
• nitrogen dioxide,
• carbon monoxide.

For example , children exposed to the gas are more likely to develop asthma, and benzene is linked to cancer , especially leukemia.

Now, researchers from Stanford University (USA) have used the National Institute of Standards and Technology’s multi-zone indoor air quality model CONTAM to accurately estimate indoor benzene concentrations and their spread in test homes. CONTAM simulated benzene concentrations in 24 building layouts ranging from 690 to 2,840 square feet, or 64 to 264 square meters.

Gas and propane stoves emit benzene, a known carcinogen, when burned. This study assessed population-level benzene exposure and associated health risks for 6.3 million U.S. residents exposed to the top 5 percent of gas stoves emitting benzene.

According to the World Health Organization (WHO), any level of benzene in air is dangerous .

It can cause:

• tiredness,
• somnolence,
• headaches and body aches,
• trembling,
• memory loss,
• eye irritation,
• skin allergies.

The obtained benzene emission data were integrated with data on the U.S. housing stock. Health risks were assessed using the USEPA health risk assessment methodology in scenarios with low, medium, and high cooker use with ventilation (open windows and/or hoods) and without ventilation.

Low usage meant five minutes of cooking on medium heat on one burner in the morning and two burners in the evening.

Average use included thirty minutes per burner on medium heat - one burner in the morning and two in the evening - without using the oven.

High usage - medium flame for 41 minutes per burner, two in the morning and four in the evening, with 134 minutes of oven use at 180 degrees Celsius in the evening.

Leaving windows open all day caused 95 to 99 percent of benzene to dissipate with heavy and moderate use. Benzene levels dropped by up to 42 percent with moderate use—one hour in the morning and afternoon, and two hours at night.

The results show that emissions from gas cookers significantly increase the risk of cancer in homes with medium or high use of gas cookers and insufficient ventilation. The highest cumulative benzene exposure was found in bedrooms, even though they were the furthest from the kitchen - because people spent more than 9 hours a day there. This shows that pollution is not only present in the cooking area .

With heavy use of gas stoves, CONTAM predicted high benzene concentrations for many of the 24 home layouts considered. Contaminants were effectively dispersed throughout the home after one or two hours of cooking, leading to significant concentrations in rooms outside the kitchen. Benzene exposure was highest in small homes (900 square feet or 83 meters) and with heavy use of unvented gas stoves.

The lifetime cumulative cancer risk (ILTCR) often exceeded safe values, especially for children, whose ILTCR was 1.85 times higher than that of adults in most scenarios with high and medium use of gas stoves.

The modeling revealed that high-emission gas stoves can spread benzene throughout the home , increasing cancer risk outside the kitchen, especially in small or unventilated homes. Americans spend 90 percent of their time indoors, where they are exposed to air pollution. Gas stoves are used by 47 million households in the U.S., and hundreds of millions worldwide.

Adequate ventilation (using open windows, hoods, or both) was found to mitigate risk, with high-efficiency ventilation hoods significantly reducing benzene exposure in kitchens . The authors emphasize the importance of combustion-related indoor air pollutants for public health protection, especially in households with limited ventilation.

The authors suggest that as remedies that may reduce the risk of cancer:

• switching to electric or induction cookers,
• opening all windows for a longer period of time,
• using high-performance hoods when cooking.

However, with high levels of benzene outdoors, political action is now necessary, comment the authors of the study.

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