Black plastic kitchen utensils, such as spatulas and chips, suddenly became suspicious last October. In a publication in Chemosphere three researchers had calculated that black recycled plastic contained dangerous levels of a chemical, BDE-209. The article received a lot of media attention, including from The New York Times and CNN. By heating or licking the black plastic, people could ingest too much of this potentially toxic substance. The tenor of many news articles: you better replace your black plastic utensils.
Until chemist Joe Schwarcz read the scientific publication and discovered a calculation error. “I follow everything about plastics, that is one of my areas,” he said on December 11 in return for National Post. Schwarcz, director of the Office for Science and Society at McGill University in Montreal, also called himself “a stickler” when it comes to numbers. And they turned out to be incorrect.
In the scientific publication, the researchers focused on flame retardants, a large group of chemicals, some of which are carcinogenic. They can also disrupt hormone functions and impair growth and reproduction. Certain groups of flame retardants are used in electrical products and electronics, including in the plastic housing, to slow the spread in the event of a fire. That plastic (including the chemicals contained in it) is subsequently recycled, for example into black kitchen utensils.
Certain flame retardants
The researchers determined the concentration of certain flame retardants (brominated and organophosphate flame retardants) in 203 products, including spatulas, chips, a pasta scoop, but also trays for sushi and fast food, and children’s toys (a mini billiards table, party beads, a pirate hook). They found quite high concentrations of flame retardants in quite a few products. Also BDE-209, which is being phased out in the United States, Europe and China. In some cases, people could ingest 34,700 nanograms of BDE-209 per day, the researchers calculated. And that, converted for a person weighing 60 kilos, was close to the maximum allowable dose of, the researchers wrote, 42,000 ng/day. But they had made a calculation error there, Schwarcz discovered. Because 60 × 7,000 ng (the maximum allowable ingested dose per kilo of body weight) is not 42,000, but 420,000!
The researchers published on December 15 a correctionin which they express their regret for the mistake they made. They adjusted a sentence in their article. The calculated daily intake did not approach the maximum allowable dose, but was tenfold under.
But it does not change the conclusion, the researchers write. Through recycling, harmful flame retardants can end up in products where they are not needed at all. More regulation is needed to stop the use of these types of dangerous additives and use safer substitutes.