The study that found black plastic utensils had a major math error

The editors of the environmental chemistry journal Chemosphere have published a striking correction to a study reporting toxic substances. Flame retardants from electronics end up in some household products made of black plastic.including kitchen utensils. The study caused a flurry of media reports a few weeks ago he urgently implored people to get rid of your kitchen spatulas and spoons. Wirecutter even offered a buying guide for what to replace them with.

the correctionreleased Sunday, will likely take some of the heat off the beleaguered utensils. The authors made a mathematical error that skewed the estimated risk of kitchen utensils by an order of magnitude.

Specifically, the authors estimated that if a cookware contained medium levels of a key toxic flame retardant (BDE-209), the cookware would transfer 34,700 nanograms of the contaminant per day based on regular use when cooking and serving hot food. The authors then compared that estimate to a reference level of BDE-209 considered safe by the Environmental Protection Agency. The EPA’s safe level is 7,000 ng (per kilogram of body weight) per day, and the authors used 60 kg as the adult weight (about 132 pounds) for their estimate. Therefore, the EPA’s safe limit would be 7,000 multiplied by 60, which would be 420,000 ng per day. That’s 12 times more than the estimated exposure of 34,700 ng per day.

However, the authors omitted a zero and reported that the EPA safe limit is 42,000 ng per day for a 60 kg adult. The error made it appear that the estimated exposure was almost at the safe limit, although in reality it was less than a tenth of the limit.

“We miscalculated the reference dose for a 60 kg adult, initially estimating it at 42,000 ng/day instead of the correct value of 420,000 ng/day,” the correction reads. “As a result, we revised our statement of ‘the calculated daily intake would be close to the US BDE-209 reference dose.’ to ‘the calculated daily intake remains an order of magnitude lower than the US BDE-209 reference dose.’ We regret this error and have updated it in our manuscript.”

Conclusion without changes

While an error of an order of magnitude seems like a significant error, the authors don’t seem to think that will change anything. “This calculation error does not affect the overall conclusion of the article,” the correction reads. The corrected study ends by stating that flame retardants “significantly contaminate” plastic products, which have a “high potential for exposure.”

Ars reached out to lead author Megan Liu but did not receive a response. Liu works for the environmental health advocacy group Toxic-Free Future, which led the study.

The study highlighted that flame retardants used in plastic electronics can, in some cases, be recycled into household items.