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Comment by gruez | Hacker News Reader

>If I go to Google Scholar and search for things like "nano micro plastics", "cytotoxicity", "oxidative stress", "immunotoxicity", "inflammation response", etc., I get back an enormous amount of (very) recent studies with conclusions I personally find concerning.

How many of them were in-vitro (ie. done in a petri dish) studies, were using absurd dosages, or cohort studies (ie. "microplastics are associated with poor health outcomes but we're not sure whether that's because microplastics are causing the poor health outcomes or people with poor outcomes also consume lots of microplastics)? My impression is that the studies on micprolastics is poor (mostly for the above reasons), which also explains why the EU concluded there was "little is known" about the risks.

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How many studies show no adverse effects, or even a single positive one?

Is it zero? ;)

How does this address my concern, which is that you can't draw much conclusions from a bunch of poorly conducted studies? For instance let's say you want to figure out whether wifi is bad for you. You do a search and find "an enormous amount of (very) recent studies with conclusions I personally find concerning", but the methodology for those studies are poor, eg. "let's microwave some mice and see what happens" (microwave is approximately the same frequency range as wifi, but orders of magnitude more power), or "let's see whether sitting next to a wifi router is associated with being fat" (people who work desk jobs tend to sit near wifi equipment). Since wifi doesn't do anything, we shouldn't expect a study to find a single positive effect, and thanks to the file drawer effect we'd expect the "no adverse effects" studies to be selected against. Furthermore because the studies are engineered to maximize effect over a short timeframe (eg. microwaving rats), it's not surprising that there are no studies showing no effects, because the studies were designed from the outset to produce some effect.

If you have a substance that you'd expect not to have positive effects (ie. not something like a vaccine), and all you have is a bunch of shitty studies that purport to show a negative effect, the correct conclusion is "we don't know either way", not "it's bad because there's studies that say it's bad but no studies that say it's neutral/good".

If you search Google scholar you’d find well over 20,000 studies. That’s more than “a bunch”, and I’d love to see how you know all of them are flawed.

Forgot to say, if it wasn't obvious: I'm not a microbiologist.

There are a few recent invivo studies on marine life showing several negative effects. I've seen also a few reviews from the past two years, for example: https://www.sciencedirect.com/science/article/pii/S258900422...

There is a lot of interest in microplastics lately so I guess we will soon know how harmful they really are.

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