Using gas stoves can raise levels of the carcinogen benzene throughout the home to dangerous levels for hours after use, according to a newly released study.

Published last week in the journal Environmental Science & Technology, the study was the first to measure benzene emissions from gas stoves and ovens, and it found that the concentrations of the toxic chemical went far above the benchmark deemed unsafe by the Environmental Protection Agency.

“We found that a single gas burner on high, or oven set to 350 Fahrenheit, for 45 minutes raised kitchen benzene concentrations above the upper estimate of benzene concentrations found in secondhand smoke in about a third of the cases that we measured,” Yannai Kashtan, a graduate student at the Stanford University Doerr School of Sustainability and lead author for this research, said in a Tuesday afternoon press briefing.

The data was collected from 87 homes across 11 counties in California and three in Colorado.

Researchers found that the chemical slowly spread throughout the home, leading to high concentrations for hours after cooking.

“Within half an hour, levels start to go up down the hall,” Rob Jackson, a senior fellow at the Stanford Woods Institute for the Environment, and a coauthor of the study, said at Tuesday’s briefing. “It takes in some cases six hours or more for benzene to go back down to background levels.”

Mounting evidence

According to the Centers for Disease Control and Prevention, acute benzene poisoning can cause symptoms such as drowsiness, dizziness, rapid or irregular heartbeat, headaches and even death at very high levels. Long-term exposure to benzene can decrease the number of red blood cells, leading to anemia, can weaken the immune system and can cause cancers such as leukemia.

A 2018 systematic review of the research, published in the Global Pediatric Health, also found that diagnoses of asthma and the frequency of reported asthma symptoms are higher in children who have been exposed to benzene in the air.

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A hot topic

Gas stoves have lately been the source of much political controversy, as other recent studies have found that the release of pollutants such as carbon monoxide and nitrogen dioxide from gas stoves increases the rate of childhood asthma.

That led one member of the U.S. Consumer Product Safety Commission to publicly muse about regulating gas stoves, including potentially banning their sale at some future date, triggering outrage from Republicans and conservatives and prompting the commission’s chairman to disavow any such plan.

The Department of Energy (DOE) proposed in late January to require increased energy efficiency from gas stoves, which would reduce pollution from them. In May, House Republicans held a hearing inveighing against that proposal and earlier this month, they passed bills intended to thwart any potential gas stove regulation.

“Gas stoves have received a lot of attention recently, and one of the reasons they are such a potential health concern is they are the only fossil fuel appliance to vent pollution indoors,” Jackson said. “We would never willingly stand over the tailpipe of a car breathing in its pollution, but we do willingly stand over our stoves, breathing in pollution they emit.”

The gas industry and its GOP allies in Congress say regulations taking gas stove models off the market unfairly limit consumer choice.

“Fifty percent of the market will not comply with DOE’s rule. That is a substantial amount of gas cooktops,” said Matthew Agen, chief regulatory counsel for energy at the American Gas Association. “A large percentage of the desirable products with the features that people are looking for will be wiped out.”