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Your black kitchen utensils are fine

Remember the scare over black kitchen utensils? Andrew Gelman points to this piece about it in the National Post:

The study estimated that using contaminated kitchenware could cause a median intake of 34,700 nanograms per day of Decabromodiphenyl ether, known as BDE-209 . . . [which] “would approach” the reference dose given by the United States Environmental Protection Agency.

....The paper correctly gives the reference dose for BDE-209 as 7,000 nanograms per kilogram of body weight per day, but calculates this into a limit for a 60-kilogram adult of 42,000 nanograms per day. So, as the paper claims, the estimated actual exposure from kitchen utensils of 34,700 nanograms per day is more than 80 per cent of the EPA limit of 42,000.

In reality, 7,000 x 60 = 420,000 nanograms. So the kitchenware contains 8% of the recommended max. Not even close to worrying.

Andrew gently says the peer reviewers are busy people and mistakes can happen, but the authors are more at fault: "I guess that part of the problem is that the incorrect number fit their story so well. When you come up with a result that doesn’t accord with the story you want to tell, you’re inclined to check it. If the result is a perfect fit, you might not even give it a second look."

I'm less gentle. This is a wild-ass screw-up of 8th grade math. It's barely conceivable that this paper could have been seen by at least half a dozen people with PhDs and not a single one noticed an error that literally jumps off the page and hits you in the face. Come on. 7,000 x 60? Even the most rudimentary sense of magnitude tells you this has to be six figures.

The authors call this a typo, which it isn't. If it were just a transcription error they'd have the proper estimate (8%) and recommendations with just a puzzling missing zero. This mistake carried through the whole paper.

The worst part, maybe, is that the authors don't care. They've submitted a correction, but stand by everything else on the grounds that anything above 0% is unacceptable. This is ridiculous. If that were so, there'd be no point in even doing the study. We already knew there was some BDE-209 there.

Oh well. Just another black eye for activist-supported research. The hits keep rolling in.

39 thoughts on “Your black kitchen utensils are fine

  1. rich1812

    As a frequent reviewer of academic papers, the reviewers shouldn't be left off the hook. Part of their job as reviewer is to catch glitches like this, and being busy isn't an excuse.

    1. deathawaits

      Hey Rich, could you review my paper? Oh wait, you seem to be on honest reviewer, so yeah I will find someone else.

      In July 2023, the Chemosphere was put on hold in the Web of Science Master Journal List due to concerns about the quality of its content. As of May 2024, more than 60 papers had been marked with expressions of concern.

      1. FrankM

        Umm....no. You don't get to pick your reviewers. That's done by the editor of the journal. And reviews are confidential - the reviewers are not disclosed to the author of the paper.

    2. FrankM

      I have also been a reviewer of academic papers, and I find it hard to believe that the reviewers missed that. It's pretty obvious. One would assume that the reviewers are numerically literate.

      1. Vog46

        Hmmm
        "One would assume that the reviewers are numerically literate."

        OR, they ran out of fingers to use - (like I do sometimes)

  2. lancc

    Yeah, the reviewers are supposed to check the fine print and consider whether the data and conclusions make sense. That part about determining that the data make sense includes reviewing the calculations. Otherwise, why have reviewers?

  3. Salamander

    Then there are the credulous reporters, who express scorn and fear of anything arithmetic-related. I've heard this too often on NPR (NPR! where you'd think they would assume an educated audience!!).

    In one appalling story years ago, a reporter was interviewing the mathematician/programmer responsible for the Mathematica software, and asked him whether science or math had ever discovered a solution to "the quadratic equation" and could his software do it.

    It being radio, you could hear the man's jaw drop.

  4. skeptonomist

    They do rely on it:

    "Applying the transfer rate derived in those experiments (11.7%) to the median concentration of BDE-209 in the cooking utensils in this study, we obtained an estimated daily intake of 34,700 ng/day from the use of contaminated utensils (see SI for methods). This compares to a ∑BDE intake in the U.S. of about 250 ng/day from home dust ingestion and about 50 ng/day from food (Besis and Samara, 2012) and would approach the U.S. BDE-209 reference dose of 7000 ng/kg bw/day (42,000 ng/day for a 60 kg adult) (United States Environmental Protection Agency, 2008)."

    This is the punch line of the entire paper, and it clearly misrepresents the results.

    The authors have the responsibility to get these things right before submission.

    1. Yehouda

      No, this is not the punch line.
      The punch line, by definition, is either in the abstract or the conclusions.
      And is clear from your quote, they don't actually use the number, they just mention it.
      And they don't represent it as their results, either.

      1. rick_jones

        They "use" the number in so far as they draw _a_ conclusion about exposure levels based on it. Perhaps it isn't "the" conclusion. I'd love to know where/how to find the full thing pre-this breaking.

        1. Yehouda

          "They "use" the number in so far as they draw _a_ conclusion about exposure levels based on it"

          That is simply a false statement. They did not draw any conclusion based on it.

          The reference I give above is the actual paper, though in principle may be fixed. The bad number is still in.

          1. rick_jones

            Perhaps you and I are using different definitions of "conclusion." They took their estimated intake, and the incorrect multiplication, and concluded in the layman's sense of the word at least that the intake approached the reference dose. They didn't just state the estimated intake and the reference dose and leave the rest to the reader. They went ahead and wrote "and would approach the U.S. BDE-209 reference dose"

                1. Yehouda

                  "1
                  a:
                  a reasoned judgment : inference

                  The obvious conclusion is that she was negligent.

                  b:
                  the necessary consequence of two or more propositions taken as premises

                  especially : the inferred proposition of a syllogism"

                  Neither of these fits here.
                  I give up.

                  1. ScentOfViolets

                    What an obnoxious little shit are. No, the definitions given fit the sense of how he's using the word as I understand it. But you unilaterally say he's not, then refuse to explain why, and finally declare victory and run away.

          2. KenSchulz

            They drew the conclusion that exposure would ‘approach the reference dose’. That’s a pretty strong suggestion that use of black utensils is concerning.

  5. Hank

    Well, damn, I'd like a refund for throwing my black kitchen utensils away. But, I really did need an upgrade and am happy with the silicon ones I replaced them with.

  6. rick_jones

    Kuang et al. estimated daily exposure to BDE-209 from contaminated utensils after conducting migration experiments simulating the use of these utensils in hot oil. Applying the transfer rate derived in those experiments (11.7%) to the median concentration of BDE-209 in the cooking utensils in this study, we obtained an estimated daily intake of 34,700 ng/day from the use of contaminated utensils (see SI for methods).

    Plastic utensils in hot oil?!? And what of Kuang et al I could read, didn't say how hot and for how long. I assume that lurks in the full PDF.

    1. rick_jones

      https://www.nbcnews.com/select/shopping/black-plastic-cooking-utensils-rcna183495

      If you don’t want to give up your black plastic utensils — after all, they’re some of the most affordable — there are things you can do to mitigate their risk. The easiest thing would be to avoid using anything made from recycled plastic. Unfortunately, most utensils aren’t labeled with the type of plastic used. With that in mind, it is possible to lower the risk factors even if your ones are made from recycled materials. “You want to minimize the chances of harmful chemicals leaching from them,” says Li. “Leaching is more likely to happen under three main conditions: high temperatures, because heat makes molecules move more actively, increasing the chances of chemicals migrating out of the plastic; long-time cooking, where longer exposure gives more time for chemicals to leach; and oily environments, since many harmful substances are lipophilic, meaning they can dissolve more easily in fats or oils.”

      I guess that explains why oils were used.

  7. SwamiRedux

    Come on Kevin, it's obvious they got confused by the SI units. What's this "nanogram" "kilogram" nonsense? True patriots use the Imperial system.

    Wait, there's something wrong with my last sentence.

  8. jeffreycmcmahon

    I feel tiresome doing this over and over again, but this has been today's episode of "That thing you're worried about (poisonous cookware)? It's not a big deal to Kevin Drum (this time for legitimate, quantifiable reasons)"

    1. Crissa

      You can find toxic substances in anything except a few kinds of ceramics and glassware - but even they're not free of hazards and chemical coatings.

  9. Justin

    Enemy Drones in New Jersey and plastic utensils!

    Practicing the assassination of… someone! And poison too!

    Oh the humanity!

  10. Salamander

    Okay, so the solution is obvious. Your (black, silicone, whatever) spats leach Chemicals that Will Kill You. So will your non-stick pans, which is why you bought your Deadly Plastic spats to begin with, so they wouldn't damage The Deadly Non-Stick Surface.

    Go back to cast iron, steel, aluminum etc pans and similar spatulas.

    1. ScentOfViolets

      Actually, Eggs taste ever-so-much-more-better when fried in a cast iron skillet, and, I would wager, there are more than a few households that keep a small one for just that reason. Fun fact: Do you know what's better than a cast iron skillet for frying eggs? A gold skillet. A small, but extremely heavy gold skillet as demonstrated in a National Geographic from many years ago.

      On Edit: I'm guessing the people who own one skew older if for no other reason than they inherited it from their mother.

      1. ScentOfViolets

        That was disproven decades ago, like , sometime in the 90's. That's not quite correct, of course. The sciencey way to say this is that as of 2024 there is no study that associates Alzheimer's with aluminum.

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