The sealant used on kitchen cabinets can release PCBs, according to a new study.
Polychlorinated biphenyls (PCBs) are chemicals that were once used in the manufacture of insulation, electrical equipment, and other items but are no longer used because they are carcinogens. They were banned in the 1970s, and they tend to be found in Superfund sites, or those areas identified by the Environmental Protection Agency as contaminated with hazardous waste.
In an analysis published this week in the journal Environmental Science & Technology, University of Iowa researchers tested 16 homes and found that three types of PCBs (there are more than 200 in existence) were elevated in some of the homes. After testing stoves, floors, walls, and cabinets, they determined that kitchen cabinets in homes built or remodeled in the last five years were a problem, but not those in older homes.
"We only noticed it in new or newly installed kitchen cabinets so probably —although we don’t really know for sure — over time it decreases," senior study author Keri Hornbuckle, professor of civil environmental engineering at the University of Iowa in Iowa City, told BuzzFeed News.
The researchers think that the problem stems from a chemical called 2,4-dichlorobenzoyl peroxide, which can be found in the polymer resin used as a cabinet sealant. PCBs are most likely produced accidentally in the resin's manufacturing process. The homes had a variety of cabinets, and the manufacturing process is common, so the researchers think this might be a problem with many different types of cabinets.
"It may be a concern for those who have new kitchen cabinets but may not a concern for people who have had their kitchen cabinets for a while," Hornbuckle said.
"Although PCBs are banned from purposeful commercial production and sales, they weren’t banned from being produced accidentally," Hornbuckle said.
It's not clear what, if any, health risks are associated with the PCBs released by new kitchen cabinets.
PCBs, without a doubt, are hazardous to health. But it's not clear if the amounts found in the study pose any health risk.
"There have been lots of studies on their toxicity and it’s pretty clear that these are among the worst environmental contaminants out there," Hornbuckle said. They are known carcinogens and neurotoxins, and can affect hormones and fat metabolism, she said.
But the health impact is unknown. "We are engineers and chemists and not toxicologists so I want to be kind of cautious," she said. "I don’t think anyone knows, in part because this source, and the mechanism of inhaling them, hasn’t been studied enough," she said.
Other PCB researchers who were not involved in the study agreed that finding the chemicals in homes is not great — but exactly how bad it is is unclear.
Dr. Jens Peter Bonde, a professor of occupational and environmental medicine in the department of public health at the University of Copenhagen, called it surprising and "disturbing" that the chemicals were found in cabinets, but he didn't consider them a health risk.
The "levels are extremely low and we have no evidence of health effects at these low levels, but studies are still ongoing," Bonde said in an email. "We may be surprised once more."
This isn't the first time PCBs have been found to contaminate air.
Traditionally PCBs were thought to be mostly a risk from eating them, such as by consuming fatty fish from PCB-contaminated lakes and rivers. But increasingly researchers are finding the chemicals in the air.
They've been found as a byproduct of the manufacture of brightly colored paint pigments, for example, and in schools that have older PCB-containing caulking material and light fixtures.
"We have these two major groups of PCBs," Wendy Heiger-Bernays, clinical professor of environmental health at Boston University School of Public Health, told BuzzFeed News.
One group was used in electronics manufacture and can contaminate food and bodies of water, and others have been found in the air, particularly in schools. "The Hornbuckle group has taken it one step further and asked — if they are in schools, are they in other places?"
Heiger-Bernays, who studies PCB contamination in New Bedford Harbor was confident that the findings were accurate. "Keri Hornbuckle is fantastic at the work she does," she said.
However, the PCB levels found in the new study were lower than those found in schools by "orders of magnitude," said Heiger-Bernays.
"I can’t say this poses a health risk and I can’t quantify this health risk. I can’t do that and nobody can do that," she said. "But I can say that these levels are concerning and that we need to decrease our overall exposure to PCBs."
So how can you avoid PCBs? Better ventilation is key.
"I think it’s important for people from a practical perspective to open their windows and ventilate," said Heiger-Bernays, who said she would crack a window while in the kitchen, even in the winter.
While it's not true everywhere, in most places in the US outdoor air can be less polluted than indoor air, at least in terms of these types of chemicals, said Hornbuckle. "Improving ventilation in your home can reduce the concentration and exposure," she said. “When it’s nice out, open your windows," she said.
And although some new cabinets might not have the chemical, it can be hard to tell.
"It’s likely that there are cabinet companies and cabinet commercial products that don’t have this signal in them," said lead study author Nicholas Herkert, a graduate student at the University of Iowa. "Based on this initial finding, we just don’t know what products have them and which ones don’t."