> 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.