High levels of the carcinogen benzene were discovered in homes where gas stoves were used by researchers from Stanford University.
Homes are polluted with benzene by gas stoves, with more of the known carcinogen being emitted than what is present in secondhand smoke, as indicated by a recent study.
The study, recently published in Environmental Science & Technology, represents the first examination of benzene levels inside homes equipped with gas stoves. This comes as the debate over state and local initiatives to phase out these appliances intensifies.
The air in homes with gas ovens and cooktops in California and Colorado was sampled by researchers, and it was compared to that in homes with electric ones. The analysis revealed that gas-burning appliances emitted 10 to 25 times more benzene than electric stoves.
During a virtual meeting with reporters on Tuesday, Rob Jackson, a Stanford University professor of Earth system science, mentioned,
“We would never willingly stand over the tailpipe of a car, breathing its pollution. But we do willingly stand over our stoves, breathing the pollution they emit.”
In California, deliberations are underway regarding the potential phasing out of gas stoves and gas-fueled space and water heaters in homes. Several cities in the state have already prohibited the installation of gas appliances in future new homes or have provided incentives for developers to opt for electric appliances instead.
However, in April 2023, a gas ban for new buildings in Berkeley, the nation’s first such measure, was overturned by a federal appeals court. Some legal scholars have suggested that the decision by the 9th U.S. Circuit Court of Appeals could deter other states and cities from considering similar bans.
At the national level, political tensions have been stirred by the issue. Two bills were passed by the GOP-controlled House to prevent federal agencies from regulating gas stoves. One of these bills is intended to hinder a Department of Energy proposal that would result in half of the gas stove models in the market being eliminated. The other bill, which garnered support from 29 Democrats, seeks to prevent the Consumer Product Safety Commission from prohibiting gas stoves.
Neither of these bills is likely to be passed by the Democratic-controlled Senate. The latter legislation also faced opposition from the Biden administration, which asserted in a statement that the bill
“would undermine science-based Consumer Product Safety Commission decision-making and impede sensible efforts to assist Americans in reducing their energy expenses.”
During the press conference on the Stanford study held on Tuesday, the health risks associated with benzene were underscored by the researchers.
According to Dr. Jan Kirsch, a retired oncologist, scientists have been aware for a century that high doses of benzene, such as those encountered by certain workers in the oil and gas industry, can induce cancer. She mentioned that metabolites of benzene accumulate in bone marrow and lead to genetic and chromosomal changes.
However, she noted,
“there is increasing evidence that even lower doses, unlike those found in industry settings, can also trigger these harmful effects.”
The study revealed that benzene emitted from gas stoves was dispersed throughout homes, with instances where levels of this carcinogen in bedrooms were raised hours after the stove had been turned off.
The benzene concentrations observed in kitchens following stove usage often exceeded the peak levels reported to the EPA at the perimeters of oil refineries in California and Colorado, as noted by Yannai Kashtan, the study’s lead author.
According to Jackson, the vents commonly installed in microwave ovens above gas burners essentially only circulated the benzene emissions. While an external vent hood can reduce benzene concentrations, he added, it doesn’t necessarily bring them below health standards.
Kirsch acknowledged that the study might cause concern for individuals who have been using gas stoves for extended periods, particularly parents.
“The intention is not to induce panic,” she remarked. “The intention is, when there are risks involved, to mitigate them.”
Jackson suggested that opting for a zero-emissions induction stove is a favorable choice when replacing a gas stove. More cost-effective alternatives include a countertop induction cooktop, a slow cooker, or an electric toaster oven. He emphasized the importance of opening windows when using a gas appliance.
Exposure pathways to the carcinogen benzene are well-established from tobacco smoke, oil and gas development, refining, gasoline pumping, and gasoline and diesel combustion. Combustion has also been linked to the formation of nitrogen dioxide, carbon monoxide, and formaldehyde indoors from gas stoves. To our knowledge, however, no research has quantified the formation of benzene indoors from gas combustion by stoves.
Across 87 homes in California and Colorado, natural gas and propane combustion emitted detectable and repeatable levels of benzene that in some homes raised indoor benzene concentrations above well-established health benchmarks. Mean benzene emissions from gas and propane burners on high and ovens set to 350 °F ranged from 2.8 to 6.5 μg min−1, 10 to 25 times higher than emissions from electric coil and radiant alternatives; neither induction stoves nor the food being cooked emitted detectable benzene. Benzene produced by gas and propane stoves also migrated throughout homes, in some cases elevating bedroom benzene concentrations above chronic health benchmarks for hours after the stove was turned off.
Combustion of gas and propane from stoves may be a substantial benzene exposure pathway and can reduce indoor air quality.