Study compares stove pollution with cigarette smoke – 06/29/2023 – Health

The use of a single burner on a gas stove can raise the concentration of benzene, a substance linked to the risk of cancer, in homes above that found in passive tobacco smoke, according to a new study.

For the peer-reviewed study, researchers at Stanford University’s Doerr School of Sustainability measured benzene emissions from stoves in 87 homes in California and Colorado.

They found that natural gas and propane stoves emit benzene in concentrations often above health standards set by the World Health Organization and other public bodies.

In about one-third of homes, a single gas burner at maximum level or an oven set to 180°C for 45 minutes raised benzene levels above the upper range of indoor concentrations seen in secondhand tobacco smoke, the researchers found. They noted that similar concentrations, when identified in 2020 near schools in Greater Los Angeles and Colorado’s Front Range, led to investigations by local authorities.

“I found it surprising,” said Yannai Kashtan, lead author of the study, “that the concentrations that triggered a public outcry when they were detected outdoors are the same as those we found repeatedly indoors, just from stoves.”

A growing body of research has documented significant indoor air pollution and negative health effects caused by gas stoves. They also emit other harmful pollutants like nitrogen dioxide, carbon monoxide and formaldehyde, and they can still leak methane, a potent greenhouse gas, even when turned off. A study published in December estimated that 12.7% of childhood asthma in the United States was linked to gas stoves.

But the most recent study, published last week in the journal Environmental Science and Technology, was the first to focus on quantifying the benzene that comes out of the stove flame in the combustion process.

The United Nations International Agency for Research on Cancer and the US Environmental Protection Agency define benzene as a human carcinogen. Breathing in the chemical can increase your risk of leukemia and lymphoma, among other serious health effects. Doctors say that no level of exposure is safe.

The Stanford team measured emissions from the food itself, frying some fish as well as bacon, and found negligible benzene emissions. Household emissions from electric and induction cooktops are also negligible, according to Stanford research and other studies.

Concerns about the health effects of gas stoves have already led some US cities and states to try to phase out gas connections in residential buildings. The federal government is moving to tighten efficiency criteria for gas stoves.

Still, the issue has become politicized. On the last day 14, the US Republican deputies approved a bill that prevents federal funds from being used to regulate gas stoves as dangerous products. The measure was not expected to pass the Senate, but it highlighted the division on the issue among the country’s politicians, despite the science.

Kashtan, a doctoral candidate who is the principal investigator on the Stanford paper, noted that the study focused on single-family homes in California and Colorado, which tend to be larger than apartments in big cities like New York. More recent tests by the Stanford team detected higher concentrations of some pollutants from gas stoves in small kitchens in New York and found that these pollutants spread quickly throughout the home and sometimes lingered for hours.

Janice Kirsch, an oncologist and former investigator of a large-scale childhood leukemia study who was not involved in the Stanford research, said the levels of benzene researchers found coming out of gas stoves in people’s homes were alarming.

“We knew that when you burn methane you get benzene. But actually taking the measurements is innovative, and the levels are higher than expected. It’s much more dangerous,” Kirsch said. “Benzene is the stuff nightmares are made of.”

Of particular concern to her is that more and more research shows that people are being exposed to harmful chemicals both outside the home, from things like traffic, factories or smoke from wildfires, and inside.

But at home, at least, people have a little more control over their exposure. “It gives us a way forward,” said Kirsch. People could buy relatively inexpensive induction hobs, she said, or use toasters and electric kettles when possible. “And ventilate,” she said. “We need to ventilate.”

Translated by Luiz Roberto M. Gonçalves