Called it!
> To be honest, after reading some of these microplastics papers I'm starting to suspect most of them are bullshit. Plastics are everywhere in a modern lab and rarely do these papers have proper controls, which I suspect would show that there is a baseline level of microplastic contamination in labs that is unavoidable. Petri dishes, pipettes, microplates, EVERYTHING is plastic, packaged in plastic, and cleaned using plastic tools, all by people wearing tons of synthetic fibers.
> We went through this same nonsense when genetic sequencers first became available until people got it into their heads that DNA contamination was everywhere and that we had to be really careful with sample collection and statistical methods. [1]
I haven't really read the studies but shouldn't they have negative controls to negate these effects? Wouldn't that let the author's correct for a baseline contamination level in the lab?
That was the difficulty with DNA: how do you make that control if everything is contaminated and minor variations in protocol (like wafting your hands over the samples one too many times) changes the baseline?
It took years to figure out proper methods and many subfields have their own adjusted procedures and sometimes even statistical models. At least with DNA you could denature it very effectively, I’m not sure how they’re going to figure out the contamination issue with microplastics.
I have worked at a sequencing center before. DNA contamination is easier to mitigate because the lab disposables aren't made out of what you are testing. Disposables are almost always plastic and tend to have minimal DNA contamination. Environmental DNA contamination is largely mitigated with PCR hoods and careful protocols/practices. However, these procedures don't mitigate DNA contamination at the collection level, which is likely where the statistical models you mentioned help.
I can't imagine wafting your hands over the tubes would change the plastic amounts substantially compared to whatever negative controls the papers used. But again, I am not an expert on this kind of analytical chemistry. I always worry more about batch effects. But it does seem like microplastics are becoming the new microbiome.
On the one hand, hundreds or perhaps thousands of studies might be wrong. On the other hand, this one might be wrong. Who's to say?
Not even that! This study doesn't even say contamination is causing overestimation. It says that it's possible.
But as mentioned elsewhere in the thread, everyone knows that it's possible and take measure to mitigate it.
A paper that said those mitigations were insufficient or empirically found not to work would be interesting. A paper saying "you should mitigate this" is... not very interesting.
> Not even that! This study doesn't even say contamination is causing overestimation. It says that it's possible.
From the article:
> They found that on average, the gloves imparted about 2,000 false positives per millimeter squared area.
I dunno, that seems like a lot of false positives. Doesn’t that strongly imply that overestimation would be a pretty likely outcome here? Sounds like a completely sterile 1mm^2 area would raise a ton of false positives because of just the gloves.
The way you mitigate this is by using negative samples. Basically blank swabs/tubes/whatever that don't have the substance you're testing in it, but that is handled the same way.
Then the tested result is Actual Sample Result - Negative Sample Result.
So you'd expect a microplastic sample to have 2,000 plus N per mm^2, and N is the result of your test.
That has happened many times in scientific research. The aforementioned fad in DNA sequencing was one such case where tons of papers before proper methods were developed are entirely useless, essentially just garbage data. Another case is fMRI studies before the dead salmon experiment.
> Plastics are everywhere in a modern lab and rarely do these papers have proper controls, which I suspect would show that there is a baseline level of microplastic contamination in labs that is unavoidable. Petri dishes, pipettes, microplates, EVERYTHING is plastic, packaged in plastic, and cleaned using plastic tools, all by people wearing tons of synthetic fibers.
Maybe so, but plastics are also everywhere in our daily lives, including on the food we eat and in the clothes we wear. As we speak I just took some eggs out of a plastic carton, unwrapped some cheese from plastic wrap, and got oatmeal out of a plastic bag. The socks and pants I'm wearing are made of polyester.
If plastics cause contamination in a lab, would you not also expect similar contamination outside of the lab?
You would, but if you do studies that claim that microplastics accumulate in our bodies or even in out brains it makes a difference.
I think you underestimate how much plastic is consumed in a lab doing experiments or analysis. I suspect it's an order of magnitude or two more than people are regularly exposed to at home or other non-industrial settings.
When I was an automation engineer at a lab, each liquid handler alone could go through several pounds of plastic pipette tips in a single day. All of that is made out of plastic and coated in a different thin layer of plastic to change the wettability of the tip. Even the glassware often comes coated in plastic and all these coatings are the thin layers most likely to create microplastics from abrasion (like the force of the pipette picking up the tip!). Throw all the packaging on top of that and there is just an insane amount of plastic.
The only place I've seen more plastic consumed is industrial and food manufacturing where everything is sprayed and resprayed with plastic coatings to reduce fouling.
> That’s not to say that there is no microplastics pollution, the U-M researchers are quick to say. > > “We may be overestimating microplastics, but there should be none. There’s still a lot out there, and that’s the problem,”
shouldn't you be particularly attentive to your bias then? an article came out that _seems_ to confirm your previous belief that you arrive at without really testing? like everyone itt that is looking like the comments of an steven crowder comment section in a post about climate change