Guest Column by Sarah B.
[From your Host: This excellent essay arrived on an Open Forum, and as I sometimes do, has been elevated from Comment of the Day status to a Guest Column. I’ll even forgive Sarah for making me look bad in comparison to such thoughtful, eloquent and perceptive work.]
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“The embarrassment is that chemistry was treated as a mere technicality rather than the foundation of the entire conclusion. The embarrassment is that skepticism—real skepticism, the disciplined refusal to accept claims without robust evidence—was framed as denial rather than diligence.”
This is, in my opinion, the money quote from The Brain, Microplastics, and the Collapse of Scientific Restraint.
This particular article discusses the extraordinary claim that our brains contain a huge amount of microplastics. The problem with this claim is that the study has a fatal methodological flaw. The study relies on spectroscopy and detecting signatures of chemicals to determine a sample’s composition. However, the fats in the brain break down into similar compounds as polyethylene, which means without further differentiation methods, there is no way to tell if the “microplastics” the study detected were actually just normal lipids found in the brain. The whole article is worth reading, as it does an excellent job of explaining the issue.
I recently saw a post on Facebook that decried the idea that experts could be challenged by some novice watching a few YouTube Videos and reading a few scientific papers. This led to a long discussion in the comments, which was unfortunately extremely one-sided. Most everyone agreed that trying to correct an expert in their field was utter hubris.
“Take something you are good at, like maybe changing transmissions. Imagine someone who has watched a few YouTube videos comes up and tells you that you are doing it all wrong. How would you respond?”
The main problem with this is that, in terms of changing a transmission, we can obviously see who is right and who is wrong. The car will run, or the car will not. Indeed, if you truly are an expert in changing transmissions, you can step up and, in simple terms, explain why your process is the correct one, what is wrong with the YouTube watcher’s process, and even perhaps teach your skeptic how to do it correctly.
With any field of expertise, we have to remember that experts are people too, and all humans have flaws. Experts can be tempted by money, power, prestige, and politics. There are also limitations that even experts struggle to overcome. For example, in many branches of research, there are serious problems (often ethical in nature) in creating a good control group.
Ethics Alarms 
As always, Sarah B’s comments are well worth reading, often more than once so the most important points have a better chance of sticking
One of my least liked phrases in a news or news-analysis article is “according to experts”, because there ‘experts’ and then there are experts.
Sarah refers to reviewing studies — note the plural usage more than once in the article. I was reminded of what a doctor (who once labeled me as contentious) said, “You can’t look at just one study, you have to look at them all.”
Also note that “TLDR”. When Sarah B contributes here, I say “MABLBMR.” Maybe a bit long, but must read.
Thank you, Sarah.
OK, I read the paper. It does not actually use IR to determine the concentration. That wouldn’t work because the only IR peaks for polyethylene would be the C-H stretches around 2900 cm-1. Instead, they are using pyrolysis-GC/MS. This paper is basically a paper promoting this technique as useful, not so much one on the amount of plastics in people’s bodies. The reason I say that is because the results span an order of magnitude and they claim their repetitions of the same sample are at least +- 25%. Also, the introduction says so.
The problem with pyrolysis is that it is not the most causality-based technique. Basically, you heat the sample up until it decomposes and hope it decomposes repeatably. You find ‘signature’ compounds formed by the decomposition and hope nothing else in the sample (this is key) decomposes to that compound (or something that looks like that compound in your analysis) and that the species you are trying to detect does repeatedly form that compound in repeatable amounts.
A typical use of pyrolysis is to analyze cured paint. You can’t dissolve most cured paint, so it is hard to analyze. So, you take some paint chips, heat them up until they decompose, and see what they form when they decompose. Well, you don’t know what they form, you know the m/e ratio of the particles they form. If another sample decomposes the same way, you assume they are the same.
From a review standpoint, I have numerous problems with this paper. Most importantly, I didn’t see figures of the mass envelopes of the species they were detecting to indicate these plastics. Did they just use 1 peak and not the envelope (you should make sure the isotopic distribution is right) and did they analyze the fragmentation pattern of the peak they indicated to make sure it really is the species they think it is? Those questions weren’t answered in the paper or in the supplemental information. A second issue I have (maybe because I am not a MS specialist) is that the m/e ratios used for several of the fragments doesn’t match the mass of the fragment. Are they using a fragment of that fragment, or are they using the +2 ion? If so, I would like an explanation of why, the justification, and I would like to see the spectra. This is especially true of the polyethylene result. If you are looking just at a peak of 83, here are some common compounds with m/e of 82-84 (you often see +/ one H in MS).
https://webbook.nist.gov/cgi/cbook.cgi?Value=82-84&VType=MW&Formula=&AllowExtra=on&Units=SI
I didn’t look much at their statistical analysis of the results, because frankly, I don’t care. I would have liked to see some negative controls. I understand their position is that you can’t get human tissues without microplastics, but you could have taken a mixture of purified common fats, proteins, and nucleic acids, mixed them together with water and typical salts, and pyrolyzed them to prove that none of the peaks you are analyzing occur. This didn’t appear to have happened.
So, that is my review and recommendation for clarifications before publication. However, I wasn’t asked to review it. This points to the bigger issue. I notice that thorough reviews are not being done on many articles before publication. I gave a paper to my junior class last year and asked them to find the glaring error. They noticed “Hey, what is that big solution in the middle of the device in Figure 3?” I knew what it was, but it wasn’t actually mentioned anywhere in the article. My colleagues are doing the same thing with their classes. Second and third rate people have a hard time making criticisms like the ones I made above. The reason is, they are afraid people will realize that they don’t know as much as they pretend. I made the above criticisms because I didn’t understand how they did several things (mainly focusing on the MS identification of the plastics). As a reviewer, I should point out things that I don’t understand about the paper. I am not a specialist in these areas and it is possible that a MS expert would comprehend a standard way of reporting MS data that I don’t. As a reviewer, the author would then explain that to me and if I accept that explanation, I should drop my criticism, although I might suggest they clarify for non-specialists, especially because this is published in Nature, not in a MS journal. However, if I am not confident enough in my knowledge and ability, I may not make that criticism at all for fear of looking foolish.
Excellent comment, worthy of COTD.
My basic takeaway is this: critical thinking is good, and expert opinions are only as good as the quality of evidence provided in support.
These days, that is apparently a novel position.
I just read a snarky X post where the writer said that based on the response to the Epstein files release, the collective IQ of the Internet is 70.
Sounds a bit high to me…
And Sarah B wrote that while raising 5 children. “While raising 5 children” sounds to me like raising them at home(presumably homeschooling) which if so is not less than a gargantuan task. Think herding chickens, squirrels and cats while composing one’s thoughts and typing at the same time.
I now understand more clearly the basis of my own skepticism.
Thanks Sarah B, while I drink my 3rd cafe with French sea salt and a tablespoon of ghee because I like the outcome of the LMHR(carnivore) study.
Jack, thank you for the honor. But in regards to your flattery about my eloquence, you write a minimum of three posts a day. This took me a week. I don’t see the comparison favor myself at all.