First, I would not say "debunked" is the most appropriate term. The studies were not shown to be false, but the article highlighted that come doubts have been cast due to potential contamination confounds. The letter (Challenges in studying microplastics in human brain https://www.nature.com/articles/s41591-025-04045-3) will get integrated into methods research. See here for current citations: (https://scholar.google.com/scholar?start=0&hl=en&as_sdt=2005...). Sciencing is actually harder than it looks from the outside, and therefore research fields goes through iterations of refinement. As the article you linked to included this quote: (Prof Lamoree “It’s still a super-immature field and there’s not many labs that can do [these analyses well]. When it comes to solid tissue samples tissues, then the difficulty is they are usually taken in an operating theatre that’s full of plastic.”).

Second, I do not think anyone is claiming that microplastic pollution is not ubiquitous, because that is obvious. That microplastics get consumed is also probably not that controversial. The extent to which microplastics get consumed but do not exit the other end of the pipe is an empirical question that has methodological challenges.

Third: I think there are some subtleties here involving the size of plastic particles. Microplastics is a catch-all term these days, but a more formal definition puts microplastics at plastic particles that range from 5 mm to 1 μm (micrometer), while nanoplasticsare 1 μm down to 1 nm (nanometer). micro- and nano- plastics can require different techniques to detect.