By Hiroko Tabuchi June 17, 2023
Using a single gas-stove burner can raise indoor concentrations of benzene, which is linked to cancer risk, to above what’s found in secondhand tobacco smoke and even to levels that have prompted local investigations when detected outdoors, according to a new study.
For the peer-reviewed study, researchers at Stanford’s Doerr School of Sustainability measured benzene emissions from stoves at 87 homes in California and Colorado and found that natural gas and propane stoves emitted benzene that frequently reached indoor concentrations above health benchmarks set by the World Health Organization and other public agencies.
In about a third of the homes, a single gas burner on high or an oven set to 350 degrees Fahrenheit 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 the Colorado Front Range, led to investigations by the authorities there.
“I found it startling,” said Yannai Kashtan, the lead author of the study, “that concentrations that were enough to trigger a public outcry when they were detected outside are concentrations that we’ve found repeatedly inside, just from stoves in people’s homes.”
A mounting body of research has documented significant indoor air pollution and negative health effects from gas stoves. Gas stoves emit other harmful pollutants like nitrogen dioxide, carbon monoxide and formaldehyde and can also leak methane, a potent greenhouse gas, even when they are turned off. A study published in December estimated that 12.7 percent of childhood asthma in the United States was linked to gas-burning stoves.
But the latest study, published this week in the journal Environmental Science and Technology, was the first to focus on quantifying the benzene that comes off a stove’s flame in the process of combustion.
The United Nation’s International Agency for Research on Cancer and the U.S. Environmental Protection Agency define benzene as a human carcinogen. Breathing in the chemical can increase the risk of leukemia and lymphoma among other serious health effects. Doctors say no level of exposure is safe.
The Stanford team measured emissions from the food itself, frying up some fish, as well as bacon, and found negligible benzene emissions. Emissions in the home from electric and induction stoves are also negligible, the Stanford research and other studies have found.
Background: Stoves have become a ‘culture war’ issue. Concerns over the health effects of gas stoves have already prompted some cities and states to seek to phase out gas connections in residential buildings. The federal government is moving to strengthen efficiency standards for gas stoves.
Still, the issue has become politicized. On Wednesday, House Republicans pushed through a bill that would prevent federal funds from being used to regulate gas stoves as a hazardous product. The measure wasn’t expected to pass the Senate, but underscored the divisiveness of the issue among the nation’s politicians, despite the science.
Mr. Kashtan, a Ph.D. candidate who is the lead Stanford researcher, noted that the study focused on single-family houses in California and Colorado, which tend to be larger than apartments in big cities such as New York. More recent testing by the Stanford team detected higher concentrations of some pollutants from gas stoves in tiny New York kitchens and found that those pollutants quickly traveled throughout the home and lingered, sometimes for hours.
Dr. Janice L. Kirsch, an oncologist and former investigator on a large-scale study of childhood leukemia who was not involved in the Stanford research, said the levels of benzene the researchers found coming off gas stoves in peoples’ homes were alarming.
“We knew that when you burn methane, you get benzene. But to actually do the measurements is groundbreaking, and levels are higher than what was expected. It’s way more dangerous,” Dr. Kirsch said. “Benzene is the stuff nightmares are made of.”
What concerned her particularly was that mounting research showed how people were being exposed to harmful chemicals both outside their homes, from things like traffic, factories or wildfire smoke, and indoors.
But inside, at least, people have somewhat more control over their exposure. “That gives us a way forward,” Dr. Kirsch said. People could buy relatively inexpensive induction hot plates, she said, or use toaster ovens and electric kettles when possible. “And ventilate,” she said. “You have to ventilate.”
I’m not a republican or climate denier or anything and I’m a big proponent of environmental causes, like to an extent that might be annoying for many… but there just isn’t good enough data for me to stop preferring to cook with gas.
Elevated levels of benzene higher than those of second hand smoke do not indicate that it’s anywhere near the same level of cancer-causing as cigarette smoke - it sounds like cherry-picking.
To run a gas stove you need great ventilation in your kitchen, there hasn’t been some insane risk of cancer from cooking in commercial kitchens or well-ventilated home kitchens with gas stoves that I’m aware of. I’d be willing to bet that increased incidence of asthma would also be the result of improper ventilation as well.
I currently have an electric stove and I hate it after having gas stoves for years. Will be going back to gas ASAP.
That said everybody has their own preferences and risk-tolerances and can do whatever they want, it’s just going to take more data for me to be willing to get an induction stove when it comes time to upgrade instead of a gas one. Electric cook tops just objectively suck.
Thanks for sharing your thoughts so completely.
I don’t thing I have a problem with professional kitchens but I do with homes and more strongly apartments and lower income housing.
The supporting infrastructure for good ventilation can be refused to minimum requirements.
What type of stove do you have and what is the thing you can’t cook the way you like?
Please forgive me for the length of my other reply, this topic (the use of scary sounding data to make people do things they don’t want to, stop doing things they do want to, or spend money) has been getting under my skin lately and also I have a lot of free time because of a guild strike timing up poorly with a career change. Also I couldn’t sleep.
It was too much and I fault nobody for not reading it and will accept any heckling that results.
I’m actually super stoked on your reply.
I’m in mobile so getting to the full reply isn’t ideal until I’m at my computer.
One thing I’ll say is that this is probably the best and most civil discussion I’ve had in the internet in years.
Cheers!
Right now I’m cooking on just a regular electric stove and cooktop. I can cook whatever I want, but heat up time, temperature change time, top temperature, and temperature control are lacking. I get better results consistently on anything other than an electric cooktop. Induction stoves do handle all these things well, but there are some major quality of life issues with any glossy flat-top for me (other people may not have these issues).
Likewise, in terms of energy efficiency, for heating anything gas has always been superior to electric. That’s why radiant heat or gas is a more efficient and environmentally sound way to heat your house than electric.
Hear me out here because you’re going to think I’m an absolute moron dying on a lot of stupid hills… but this is why I’ve become disillusioned with a lot of health and environment science that gets published to get end-users to make lifestyle changes.
Lately for steaks and burgers I’m cooking outside on a charcoal grill because it just makes them taste better than my stove does… high heat / short time and the grease drips out a bit which makes me feel healthier… but it involves standing next to burning charcoal and smoke which, terrible right? Standing next to a grill inhaling all that? Burning all that charcoal into the atmosphere?
Here’s an article telling people to stop grilling with charcoal, which points out that grilling with propane is like driving your car 8 miles and charcoal 22. Here’s a uh… Ted talk? Which explains how it’s bad because of deforestation also.
But then here’s a pie-chart showing the leading causes of deforestation: chart
How many people are worrying that much about driving their car 22 miles? All these little things that bring joy to your life have less of an impact than the person who wrote the article’s daily commute in a lot of cases, industrial agriculture, suburban sprawl and the demand for paper make these environmental impacts seem like absolutely nothing. There are so many things bad for the world and ourselves out there, yet somehow it’s always us at home that need to buy new things and change our lifestyle? I do make lifestyle changes, but primarily in ways that improve my quality of life.
Sometimes it’s good science and bad reporting, we have known for a long time now how terrible cigarettes are for your health. Obviously smoking cigars or pipe tobacco means you’ll get oral, throat, or lung cancer too right? A quick google shows me dozens of articles and studies telling me so. But then you dig deeper and find that when the FDA did a review of all the available studies they found this:
Because the desired outcome was to just be able to say it’s a public health risk, they say in their conclusion that it is, but their actual data shows that non-inhalers that smoke 1-2 cigars a day have an only slightly elevated risk that does not meet the conventional criteria for statistical significance. Very few people smoke more than 1-2 cigars a day and inhaling them is painful and insane. Almost nobody reported on the study that way, instead it was reported as “See, they cause cancer” by almost all major media, except a handful of conservative publications which really ruffles my pretty far left feathers
People should cook on what they think makes their food taste best. Nobody should replace what they own because of 8.4% of children (percent of child population with asthma) having a gas stove in the house was associated with a 20% increase in diagnosis, which we are unsure if the gas stove was causal or just an irritant that led to diagnosis of existing condition. There are also studies that found no link
In my opinion, for the vast majority of people, properly installed and ventilated it’s a non-issue. Just a lot of stove selling and fear-mongering.