A couple of months ago, people were ditching their black kitchen utensils, following a slew of reports like, “Throw Out Your Black Plastic Spatula – It’s probably leaching chemicals into your cooking oil” and “Here’s why everybody is currently avoiding black plastic kitchen utensils“.
The articles referenced a study which tested hundreds of household items made of black plastic — like kitchen implements and children’s toys — and found toxic additives including hazardous flame retardants.
The authors reported the levels of some contaminants as being so high, they almost reached the safe daily limit for human exposure.
But there was a problem. The scientists involved in the study made a major miscalculation.
So before you bin your black kitchen utensils here’s what you should know.
What is black plastic and why is it bad?
Black plastic kitchenware like spoons, spatulas and reusable containers can become contaminated with toxic chemicals because they can be made from recycled electronic products.
Some electronics like computers, TVs, speakers and coffee machines, have casings made of black plastic and are treated with flame retardants to prevent electrical fires.
This kind of plastic should not end up in the recycling stream, but when products are incorrectly disposed of, that’s exactly what happens.
Why are people throwing out their black kitchen utensils?
Environmental chemistry journals aren’t known for going viral but that’s what happened with the catchily titled, “e-waste to living space: Flame retardants contaminating household items add to concern about plastic recycling“.
The article was published in a peer-reviewed journal, Chemosphere.
The study looked at 203 black plastic household products sold in the United States including kitchen utensils, takeaway containers, hair accessories and toys.
Black plastic kitchen utensils are common as they are often the cheapest. (ABC News: Billy Cooper)
The researchers found flame retardants in 85 per cent of the items and most of these retardants were made from a chemical called Decabromodiphenyl ether (referred to as BDE-209).
BDE-209 is listed on the Rotterdam and Stockholm Conventions — global treaties to protect human health and the environment from hazardous chemicals. Australia is a party to both these agreements which means importing the chemical is strictly regulated.
It can only be imported into Australia or manufactured here for essential uses, for example aircraft parts, or when the chemical is present in finished goods that are already in use. These exceptions don’t apply when BDE-209 is unintentionally present at very low levels.
BDE-209 cannot easily break down in the environment and has been found in the Parramatta River, Port Phillip Bay and the Brisbane River.
There is also evidence it can accumulate in the human body, leading to a variety of possible health outcomes still being studied — which may include cancer.
What the study got wrong
In a correction posted late last month, the authors of the study admitted they made a clanger of a mathematical error, miscalculating the safe level of exposure to BDE-209 by about 10 times.
This made it appear the exposure risk per day from a kitchen utensil almost matched the safe total daily limit set by the EPA. In reality, it was actually less than a tenth of the limit, indicating that the risk to the public was far lower than initially reported.
The paper was co-authored by three researchers, two of whom at the time of publishing worked for Toxic-Free future, an American organisation that advocates for safer household products.
In the correction the authors said, “this calculation error does not affect the overall conclusion of the paper”.
Lead author and science manager at Toxic-Free Future Megan Liu told the ABC the study was not about determining risk, but identifying whether harmful flame retardants were contaminating household products.
“Our study and other similar studies make it clear that more regulation is needed to end the use of hazardous additives in products and ensure that replacements are made with safer materials and chemicals,” she said.
How could the authors get it so wrong?
The mistake is “insanely embarrassing”, says Dr Ian Musgrave, a molecular pharmacologist with expertise in toxicology at the University of Adelaide.
“It also shows the peer reviewers were not paying enough attention,” he said.
Toxic-Free Future apologised for the error in a statement and said they were grateful to the scientists who found it.
The journal that published the initial study, Chemosphere, has since been booted from The Web of Science which is a database of scholarly articles from peer-reviewed journals.
The company that runs the database said the journal wasn’t removed because of this one paper but because it failed to meet its editorial standards more broadly.
Dr Ivan Oransky co-founded Retraction Watch which tracks mistakes in scientific papers. He said Chemosphere retracted 20 articles last December and its publisher had become aware of “compromised peer-review processes.”
Do I need to throw away my black plastic utensils?
Nothing definitive is known about how BDE-90 and other flame retardants in the same category (called PBDEs) affect humans, as most studies were done on animals.
Some studies suggest PBDEs can disturb the human endocrine system but the findings are inconsistent.
Testing on rats and mice found PBDEs can affect neurodevelopment and could lead to liver tumours when given in large doses for over 90 per cent of their life, Dr Musgrave said.
The International Agency for Research on Cancer said PBDEs were “not classifiable as to carcinogenicity” to humans due to inadequate evidence.
But researchers recently published a study suggesting a link between PBDEs and cancer mortality.
Flame retardants that have been found in some kitchen utensils are hazardous chemicals. (Giulio Saggin, file photo: ABC News)
The safe limit of BDE-90 exposure per day, which is set by the US EPA, is around 100 times less than the dose given to mice which produced no adverse health effects, Dr Musgrave said.
The researchers in the corrected paper found the potential BDE-90 exposure from the utensil was 10 times less than that safe limit.
“It’s basically safe and if you’ve got a perfectly fine black plastic spoon there’s no point throwing it out,” Dr Musgrave said.
Chief investigator at the Australian Laboratory for Emerging Contaminants, Brad Clarke, suggested a more cautious approach.
“I removed all the black plastics in our house in 2019. I now have wood, stainless steel and silicone,” Dr Clarke said.
“We call it the precautionary principle in environmental science. We might not know, but we could reasonably predict an outcome.”
He said more regulatory oversight of plastic recycling was needed.
“In the worst case of the circular economy, things end up in the loop that shouldn’t be there and then we actually start increasing the levels of these chemicals as we keep recycling them.”
Dr Clarke said he would now like to see a study on the black kitchen utensils sold in Australia, many of which are manufactured in Asia, to see if they too contain these flame retardants.
There’s been a lot of attention on these items since the Chemosphere study was published. (ABC News: Billy Cooper)
BDE-209 can currently be used for essential purposes in Australia which includes aircraft parts, car parts, electronic equipment and textiles (like curtains) that need to be anti-flammable.
But most of these exemptions for BDE-209 will expire in January 2027, a spokesperson for the Department of Climate Change, Energy, the Environment and Water told the ABC.
The exception for car parts will continue until 2036 and BDE-209 will be permitted in aircraft parts until the plane reaches the end of its service life.