By Mark Jones
2024 was the year of spatulageddon. Plastic spatulas were trashed due to reports of dangers lurking within. The journal article that raised concern contained an error, an obvious error. A correction was made, but there’s more to the story.
The study causing spatulageddon was published in the journal Chemosphere. The corresponding author is affiliated with Toxic-Free Future. The study found brominated flame retardants where they shouldn’t be, in objects used to touch food. A now banned compound, BDE-209, was deemed particularly worrisome. “Estimation of exposure to BDE-209 from contaminated kitchen utensils indicated users would have a median intake of 34,700 ng/day, exceeding estimates for intake from dust and diet” according to the authors. They went on to conclude, “Products found in this study to contain hazardous flame retardants included items with high exposure potential, including food-contact items as well as toys.”
Pretty alarming stuff. A PR push by Toxic-Free Future resulted in headlines like “Black Plastic Kitchen Tools Might Expose You to Toxic Chemicals. Here’s What to Use Instead” from the New York Times and “Throw Out Your Black Plastic Spatula” from The Atlantic. Spatulageddon was on.
Early in 2024, the Freakonomics podcast introduced me to the concept of convenient errors. Leif Nelson of Data Colada explained that a one decimal point error, potentially a typo, may well escape notice if it is the direction supporting the hypothesis. That is exactly the type of error made here. Authors missed an easily detectable factor of 10 error. Reviewers missed it. Editors missed it. Once stories started to appear, sharp-eyed readers found it.
Digging into the error left me disheartened. To determine whether BDE-209 presented an acceptable or unacceptable risk, the EPA reference dose of 7,000 ng/kg of body was used. A reference dose is the maximum amount that will not cause harm. 7,000 ng/kg body weight per day for a typical 60-kg adult is 420,000 ng/day. A convenient error was made. 42,000 ng/day was mistakenly used. Instead of concluding levels below the reference dose were okay, 80% was reported as too close for comfort and a reason for concern. Once corrected, the exposure estimate drops to a more comfortable 8%.
The estimated exposures are well below the corrected reference dose. The correction attached to the article does not back away from the conclusion that recycled plastic in food contact applications is an unreasonable risk. Others have questioned how the conclusions remain valid.
I am doubtful the paper would have been noticed with the correct reference dose. A headline claiming levels claiming spatulas are okay wouldn’t garner much attention. The convenient error got the work noticed.
But there is even more reason to doubt the conclusions. 203 items were collected and screened. Only 20 testing above 50 ppm bromine were analyzed for flame retardants. 183 items didn’t have concerning levels. The ambiguously worded abstract states that flame retardants were found in 85% of the samples when, in reality, they were detected in only 17 of 203 samples, only about 8%. The ratio is similar for kitchen items. Only 9 of 109 measured high enough for additional testing. Over 90% were okay.
Previous work by other researchers formed the basis for exposure estimates based on exposure to hot oil. That work concluded handling of objects was unlikely to cause exposure. A relationship connecting BDE-209 concentration to exposure upon heating in oil was developed and the 20 samples tested included food service ware, toys, kitchen utensils, and hair accessories. Only a subset of kitchen utensils are used with hot oil. Utensils like peelers never contact hot oil. 34,700 ng/day is calculated using the average of all 20 of the BDE-209 measurements, including the hair accessories, toys, and peelers. The highest measured spatula gives an exposure estimate less than 0.4% of the EPA reference dose. Spatulageddon should never have happened.
A couple of things are clear. Most concerning is this story illuminates failures of peer-review. Convenient errors slip through even when obvious. More subtle errors are surely being missed. Once ominous sounding science hits the press, getting it corrected in public opinion is unlikely. Recycling does create risks that aren’t present with virgin material. We have to trust actors in the recycle chain are keeping those risks tolerable. This study shows we are recycling with tolerable risks. Lastly, if you didn’t throw out your black spatula … don’t.
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Filed Under: Commentaries • insights • Technical thinking
