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Comment by gruez | Hacker News Reader

>Seems like we've known about various problems with many plastics for a good while, [...]. Can we please realise that this is probably affecting everyone

Except the science on microplastics seem... far from conclusive?

>Microplastic pollution has been associated with various adverse health conditions, including respiratory disease and inflammation, but it is not known whether there is a causative effect.[23] There is concern microplastic pollutants may act as a vector for antibiotic resistant genes and bacteria.[116]

>According to a comprehensive review of scientific evidence published by the European Union's Scientific Advice Mechanism in 2019, "little is known with respect to the human health risks of nano- and microplastics, and what is known is surrounded by considerable uncertainty". [...]

https://en.wikipedia.org/wiki/Microplastics#Human_health

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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. It's hard to quantify the actual impact in the general population. At the same time everyone is looking for explanations for the raise of early onset cancers.

>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.

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.

The roman science on lead was far from conclusive to them as well...

They didn't have the scientific method back then so it's unclear what phrases like "conclusive" in today's context would even mean to them. That said, wikipedia suggests they know of the dangers:

>In the 2nd century BC the Greek botanist Nicander described the colic and paralysis seen in lead-poisoned people.[32][5] Dioscorides, a Greek physician who lived in the 1st century AD, wrote that lead makes the mind "give way".[122][263]

>Julius Caesar's engineer, Vitruvius, reported, "water is much more wholesome from earthenware pipes than from lead pipes. For it seems to be made injurious by lead, because white lead is produced by it, and this is said to be harmful to the human body."[264] Gout, prevalent in affluent Rome, is thought to be the result of lead, or leaded eating and drinking vessels. Sugar of lead (lead(II) acetate) was used to sweeten wine, and the gout that resulted from this was known as "saturnine" gout.[265]

Just having the scientific method doesn't mean we know what's true. We just know what's easy to observe. The vast majority of what there is to know about human health hardly have a clue (e.g. psychology).

By the same token we also don't really know what the long-term effects of having plastic in your testicles are over your lifespan, because we don't have an easy way to get this data on a million people and look for correlations. Absence of evidence isn't evidence of absence.

>Absence of evidence isn't evidence of absence.

Where did I claim otherwise? If you read my comments more carefully you'd see I never made such claim. For instance in my original comment said "the science on microplastics seem... far from conclusive". That's not the same as claiming there's evidence that there's no negative effects from microplastics. Moreover, that comment is in reply to a comment which says that there is evidence that microplastics was causing "various problems" and was "probably affecting everyone".

But that's the problem with science. (I love science!)

In general, for many horrific (from an individual standpoint) problems, the time delta between "hmm, that's potentially a concern, I wonder if there's a causal relationship" to "we've conclusively proved that will kill you, and horribly" is longer than it would take to die of old age...

...but the point may be moot, because you already died a long time ago from that thing there wasn't yet conclusive evidence about.

And yet, when I was a kid, they said eating eggs would kill you horribly. So... hard problem.

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