A popular scientific study found that black plastic in common household items often contains harmful flame retardants. But now researchers say the findings contain a significant mathematical error.
A Canadian chemist first raised the alarm in a December 11 interview with the National Post. Essentially, exposure to a flame retardant from black plastic appeared to be approaching the Environmental Protection Agency (EPA)’s limit for what the agency deemed safe. However, the numbers were off by a factor of 10—the EPA’s limit of safe exposure was higher than originally reported, meaning black plastic isn’t posing such a glaring threat to people’s health.
The original team of researchers published a correction in the journal Chemosphere on December 15, walking readers through the error.
Despite this, experts agreed that avoiding black plastic kitchen utensils, takeout containers, toys, and other products is still a smart idea—particularly if that plastic is touching food.
“It doesn’t change the overall trust of the paper. The point they made was a legitimate point: that these substances should not be in these items,” said Joe Schwarcz, PhD, professor of chemistry and director of the Office for Science and Society at McGill University, who found the error.
“Nevertheless, when you publish a scientific paper you have to be precise, especially when you are alerting people to potential toxins,” he told Health.
In the original study, researchers wanted to investigate whether toxic flame retardants could make their way into household items through electronic waste recycling.
They tested 203 products—from plastic spatulas to a children’s toy necklace—for two types of flame retardants known to cause health problems: brominated flame retardants (BFRs) and organophosphate flame retardants (OPFRs).
Manufacturers put these flame retardants in black plastic used in electronics to prevent fires. However, when these products are recycled, flame retardants can get into new items without people or manufacturers knowing.
The researchers found that 85% of the products they tested contained flame retardant chemicals in general, and 65% contained a mixture of both classes of flame retardants. The highest amounts of flame retardants were found in a sushi tray, a toy car, and a kitchen peeler.
Fourteen of the 203 tested products contained decabromodiphenyl ether (BDE-209), a flame retardant banned by the EPA that has been linked to cancer. This chemical was the subject of the correction.
The researchers’ error was not related to the presence or the amount of BDE-209 in the items—rather, the researchers miscalculated the amount of the chemical that the EPA deems safe, called a reference dose.
For an adult who is 60 kilograms (about 132 pounds), the EPA’s reference dose for oral exposure to BDE-209 is 420,000 nanograms per day. But researchers accidentally had that figure as 42,000 nanograms per day.
So because the data showed that people using black plastic could be exposed to 34,700 nanograms of BDE-209 per day, researchers were alarmed. It looked like people were dangerously close to the threshold of safe exposure to the flame retardant. However, with the corrected figure, this BDE-290 exposure isn’t closely approaching the reference dose.
Despite the error, the study’s findings and recommendations still stand, said lead study author Megan Liu, science and policy manager at Toxic-Free Future. BDE-209 was just one of 11 different flame retardant chemicals found in the plastics, she said, and it’s concerning that there are flame retardants present in these products at all.
“We remain very concerned that highly hazardous toxic flame retardants—especially ones that build up in people or the food chain—were found in black plastic kitchen utensils, food serviceware, toys, and hair accessories,” Liu told Health. “They have no reason to be in these products to begin with and should be prohibited.”
In 2021, the EPA banned BDE-209 from being manufactured, processed, or distributed in the U.S. And the agency phased out the class of chemicals it belongs to—polybrominated diphenyl ethers (PBDEs)—over a decade ago, calling PBDEs “persistent, bioaccumulative, and toxic to both humans and the environment.” More recently, a study published in April found that participants with the highest levels of PBDEs in their blood had a 300% greater chance of dying from cancer.
“Kitchen spatulas and stuff like that do not need flame retardants,” said Schwarcz.
In fact, using any sort of plastic in the kitchen can be dangerous, regardless of whether it contains flame retardants, said Jaime Ross, PhD, assistant professor of neuroscience at the University of Rhode Island.
“Even if there were zero flame retardants, I still wouldn’t use plastics to cook with because the heat can cause the plastics to degrade and allow a vector for the microplastics and nanoplastics to be consumed,” she told Health. “We know that heat and plastics don’t go well together.”
A report published earlier this year found plastics contain more than 16,000 chemicals, and 4,200 have been linked to negative effects on human health or the environment.
“Plastics are a chemical,” said Ross. “Any time you ingest any type of plastic, you give the potential for it to move around your body and get into deeper tissues, including the brain.”
