Your Black Plastic Utensils (Probably) Aren’t Killing You
If you’ve recently thrown out your black plastic spatula, as several news articles have urged us to do (“ Your Favorite Spatula Could Kill You ” is the real headline), you might want to see if you can dig it back out of the trash. They were based on research whose most dramatic conclusion turned out to be a miscalculation.
To be fair, the general idea hasn’t been debunked; plastic contains many chemicals whose potential health effects are not yet well understood. And the black spatula study did reveal a serious problem in plastic production. But the problem is literally 1/10 bigger than the news would have us believe.
Why black plastic can be a health problem
The original study , which has some positives even if the math error is corrected, focused on the use of flame retardants in plastics. Fire retardants are exactly what they sound like: chemicals that make it harder for materials to catch fire. Electronic components such as computers are often manufactured using fire retardants for safety purposes.
Flame retardants, especially a family called brominated flame retardants, are suspected of causing potential health problems (such as cancer) and can accumulate in the environment. If they are used in production, they should be stored away from areas where people may consume them. And that’s where this study comes to the rescue.
The authors suspected that black plastic from electronics was being recycled into other items, such as kitchen utensils. And they found that this was indeed the case.
What’s Wrong with the Recent Study?
As Canada’s National Post reported , chemist Joe Schwartz took a closer look at the study’s numbers and discovered an error—one you’ve probably made in your high school science papers. (I know it did.) It has to do with the dosage of the chemical BDE-209. A reference dose means—very roughly, and there is a nuance to this definition —the amount of a chemical that is considered safe for consumption every day.
The authors of the article looked at the reference dose of BDE-209, which was 7,000 nanograms per kilogram of human body weight. They multiplied this by a 60-kilogram person (132 pounds, the size of a small adult) and then compared it to their findings of 34,700 nanograms per day of exposure to kitchen utensils. Wow! 34,700 is pretty darn close to the reference dose of 42,000 nanograms per day! This is definitely a cause for concern.
But this math was missing a zero. The reference dose actually increases to 420,000 nanograms. That is, 34,700 nanograms is not 83% of the reference dose, but 8.3%. This is still potentially a concern, but not to the same extent. The journal published a correction in which the authors say, “We regret this error and have updated it in our manuscript. This calculation error does not affect the overall conclusion of the article.”
The overall conclusion was that “when toxic additives are used in plastics, they can significantly contaminate products made from recycled materials that do not require fire resistance.” The authors also called for increased research and regulation to ensure plastic products are made from safer materials. And these sound like fair remarks.