Avoiding and reducing microplastic false positives from dry glove contact
pubs.rsc.orgThere is growing evidence that there is much less to worry about on microplastics on several fronts.
1. A whole cohort of core studies have been judged to have invalid methodology due to not recording baseline microplastic levels (https://www.pnas.org/doi/10.1073/pnas.2411099121)
2. Young-onset cancers (especially colorectal cancer) which were inferred to be caused by a rise in microplastics are being linked explicitly to other mechanisms and cohorts. (https://ascopubs.org/doi/10.1200/JCO.2025.43.16_suppl.3619)
> A whole cohort of core studies have been judged to have invalid methodology due to not recording baseline microplastic levels (https://www.pnas.org/doi/10.1073/pnas.2411099121)
This does not say that and it's irresponsible to summarize it that way. That's a letter addressing a specific study from 2024 (which did record baseline levels because that's a standard experimental design step), arguing that it used an inadequate control so may have had background contamination when reporting the level of microplastics found in bottled water.
A "cohort of core studies" were not involved, and nothing was "judged to have invalid methodology". The study authors also replied, arguing that their choice of blanks was actually the better one: https://www.pnas.org/doi/10.1073/pnas.2415874121
There's been a slightly weird trend of people on HN that seem so eager to judge the microplastic story as overblown and unsupported that they're overstating and overextrapolating the smallest counter evidence into its own competing narrative, as if what we needed were more narratives. Resist this! That's not how good science or science communication is done.
I respectfully disagree, this was a commonly cited technique for measuring microplastics, which is why it calls into question many studies. Thanks for calling me weird :) I guess the suggestion though is I'm paid by big plastic or something, no infact I'm just a guy reading papers who is scared of death like everyone else.
> I respectfully disagree, this was a commonly cited technique for measuring microplastics, which is why it calls into question many studies.
What exactly was a commonly cited technique and where is this citation?
Regardless, you said "invalid methodology due to not recording baseline microplastic levels" when that was not the case and wasn't the letter's objection to the study's methodology.
> Thanks for calling me weird :) I guess the suggestion though is I'm paid by big plastic or something, no infact I'm just a guy reading papers who is scared of death like everyone else.
I said the trend was weird, but feel free to pick another adjective. Self contradictory, for instance. Sick of people overextrapolating from these "bombshell" microplastic papers, I will now overextrapolate from these "bombshell" methodological papers.
Look at the publications of the author of that letter and Cassandra Rauert, the lead author of the paper on detecting plastics in human blood that you linked below. Both of them have several publications on the almost universal contamination of the planet with microplastics and are clearly worried about the impact of this. Them insisting on and helping with better science from their colleagues is not laying the question to rest, it's a call to more rigorous action (literally[2]). It is scientific malpractice to call that "growing evidence that there is much less to worry about on microplastics".
I've heavily couched my language and not claimed authority. If you are looking for examples of irresponsible communication, look inward. You've mixed real quotes from me with ones you've injected ""bombshell"". I purposefully did not use such language. I get this is an issue that can emote, and I respect your view. Perhaps you've underestimated how much of your view I share.
I think those papers mostly show that parts of the microplastics literature were overstated or methodologically weak, not that microplastics are harmless.
The PNAS paper is a pretty good critique of contamination/baseline issues, and I agree some of the “microplastics are causing young-onset cancer” claims got ahead of the evidence.
But the broader concern still exists: people are clearly exposed constantly, particles are being found in human tissue, and there are plausible mechanisms for harm. So no, there is not "much less to worry".
I agree that there is not evidence to "not worry", but many explicit worries are being accounted for.
Also - in terms of human tissue:
"The problem is that some small molecules in the fumes derived from polyethylene and PVC can also be produced from fats in human tissue. Human samples are “digested” with chemicals to remove tissue before analysis, but if some remains the result can be false positives for MNPs. Rauert’s paper lists 18 studies that did not include consideration of the risk of such false positives." (https://www.theguardian.com/environment/2026/jan/13/micropla...)
and Rauert's paper (https://pubs.acs.org/doi/10.1021/acs.est.4c12599)
"Exercise induced gastrointestinal injury"!
Can't read the full study, but it seems to be specifically about people who run ultramarathons. Which sounds like a very small subset of the general population. I doubt that tiny cohort is in any way responsible for the overall increase in bowel cancer in younger people.
Actually this is the shocking part - it actually is enough to move the needle. Incidents of young people with cancer is small so a 100% increase can be driven by a small absolute number of patients. There has been an absolutely enormous increasing in high endurance sport something more like 20x (or 1900% increase) and ultramarathon/marathon runners are 7.5x more likely to get colon cancer, so this leads to a surprisingly large relative increase in colon cancer.
I feel the field of microplastics has done itself no favours by referring to everything < 5mm as a microplastic particle. 5mm is huge. In american terms, it's amost as wide as a .22 calibre bullet, or a popcorn kernel
Summary: dry contact with nearly any laboratory glove will lead to sample contamination and over estimation of microplastics. They found one type of clean room gloves that contaminate less.
Is there any indication on how bad this really is?
Around 2000 to over 7000 false positives per mm^2 based on the type of glove. Essentially, regular lab gloves shed enough particles to swamp microplastic measurements to warrant switching to clean room gloves for this type of analysis.
Shouldn't any lab analysis have control samples to detect environment contamination like this?
It's difficult to avoid contamination, since everything (samples, containers, equipements, etc) will have been in contact with glove at least once, and good decontamination is very hard.
Yes, exactly, that's why you use control samples to get the baseline.
You see how it's a bit of a self-starting problem?
Let's say you want to determine the amount of microplastics in ocean water samples.
You'd create a control by creating saline solution with distilled water and sodium chloride. Then you treat both the control and your sample(s) the same way in the analysis.
Surely something should tick you off when the microplastic levels aren't much lower in your control compared to your actual sample?
They are handling both the control and the sample with gloves. Which is the same way. They are contaminating both. It's useless to argue about how contamination could have theoretically been avoided in an alternate past in hindisght. You don't realize there's a potential contaminant until you do and then you mitigate it. I'm sure they are smart enough now that they realize they are systematically introducing contaminants, they will be able to figure out how to control for it.
>They are handling both the control and the sample with gloves. Which is the same way. They are contaminating both.
That's the point. If the control also gets contaminated then they should get >0 results in the control (when basically zero was expected) and that should have raised awareness of this problem pretty much immediately.
Freshly cleaved mica has an extremely clean and flat surface.
This shouldn't really be a problem. Just use aseptic techniques to avoid glove contact (direct, indirect, and airborne) with the test material.
Now, I'm worried about people preparing my food with gloves.
Am I the only person who's a bit disturbed by that (new?) trend of chefs always wearing black latex gloves? As a person who dislikes having sticky hands I can appreciate the appeal but something about it seems a bit off.
“Are you wearing gloves? That’s disgusting. Use your bare hands, you animal.”
Actually bare hands ok while working in food production if correctly washed with an antimicrobial agent, and assuming one doesn't pick his nose on the job.
Picking noses presumably isn't a unique problem to bare hand prep, unless the ungloved finger is somehow a more tempting scoop?
I find that picking your nose can be a unconscious thing you do, but the sensation of sticking a glove into your nose quickly makes it very not unconscious very fast
But of course, hopefully the person in question will choose to change the glove.
Otherwise yes, glove wearing dogma is overdone, however still, should probably wear them.
Yeah, I wouldn't care if someone cooks with bare hands, assuming they actually wash their hands properly. I'm only unhappy when I see them taking their nasty smartphone out of their pocket and doing something with that, then continuing to cook without washing their hands (or without putting on new gloves). Gross!
Just like high end chefs do. It works fine.
"I only allow robots with stainless steel tools to prepare and serve my food."
“He wants metal; they always do.”
— Segregationist, Isaac Asimov, 1967: <https://archive.org/details/Fantasy_Science_Fiction_v035n04_...>