Chlorinated paraffins, a class of chemicals banned a decade ago for their cancer-causing effects, have been found in a wide range of household products in Canada, according to researchers at the University of Toronto.

In 2013, Canada and several other countries banned the manufacture, use, or import of the chemicals, which are used as plasticizers and flame retardants. The ban was because of their toxicity and persistence, and they were among the chemicals listed for elimination under the Stockholm Convention on Persistent Organic Pollutants in 2017. But they can still be found at high concentrations in indoor air samples and dust. So Steven Kutarna, an environmental chemist at UofT, and his colleagues went looking for potential sources.

They tested a wide array of everyday household items, including clothing, carpets, electronics, personal care items, and toys purchased in Canada. With the ban in place for 10 years, they weren’t expecting to find much, especially in new products. But they were in for a surprise. “We found them in almost all the products we tested,” says Kutarna.

The banned chemicals were detected in 84 out of 96 products tested. Most had just trace amounts, but high concentrations – in some cases up to 1% by weight – were found in headphone wires and children’s toys. The work was published in Environmental Science: Processes and Impacts.

Marta Venier, an environmental chemist at Indiana University, has previously found other potentially harmful chemicals in children’s clothing. She says it’s worrying to see another group of chemicals in products that should not be there. And while it is difficult to say what harm they might cause, the relatively high levels are still cause for concern, especially since there are likely other chemicals present as well such as per- and polyfluoroalkyl substances (PFAS).

“When you add it all up, these products have a chemical soup in them that is persistent and leads to continual exposure, with potentially toxic effects,” she says.

And despite the ban, it’s clear that the presence of these chemicals is no accident. It can take a while for regulations to have an effect, but 10 years is a long time by any standard. “When you get into these percentage levels, they’ve been added on purpose,” says Venier. “It’s not contamination or bad luck.”

Kutarna says it is difficult to trace the source of the chlorinated paraffins, because there is not a lot of manufacturing information available. But it is likely that even the manufacturers are unaware that the raw materials they use to make their products contain banned ingredients. Testing for them is technically challenging, and suppliers are not required to list the chemicals they use. “There is no international standard for reporting these compounds,” says Kutarna.

To improve safety, Kutarna would like to see additional transparency in the supply chain and improved adherence to Canadian and international rules. “We need to enforce the rules that are on the books, and make sure these chemicals are reported all along the supply chain,” he says.