Let's assume you're right, and there's 3.5 grams of plastic in your brain (there isn't, but let's run with it).
You've been secretly living with this horrible condition for long enough for it to happen -- remember, this is happening a nanogram at a time, for years and years! This is not a fast process!
Are you dead? No? Hm.
Perhaps you ought to rethink your priors. I'm not saying you're absolutely wrong -- maybe the right answer really is that "0 is the right number". But maybe the answer is that it doesn't matter that much, and you're exaggerating the impact. More to the point, when you simply leap to the most exaggerated conclusion from a bad paper with sketchy methodology, you're not doing science, or being data-driven -- you're just panicking.
Why assume? There's multiple studies showing microplastics in human brains. Are they all "sketchy" too?
What organ in the body hasn't been shown to be contaminated? Significant and increasing levels have been found in lungs, livers, kidneys, spleens, intestines, hearts, placentas, blood, fat tissue, lymph nodes... All sketchy studies in your view? No? Then why the exception for brains?
Microplastics have been found from the top of Everest to the bottom of the Mariana Trench. They're in 60-80% of all wild species examined. Sketchy? Exaggerated? Bring the data if you have it. It would want to be very strong stuff..
To loudly cast doubt on a study like this, and claim you know the weight of microplastic in people's brains is under 3.5g, you'd want to bring some substance... You haven't brought any; none at all.
> Are you dead? No? Hm.
Do I really need to explain that health is a spectrum - that 'alive' is not equivalent to healthy? That "not immediately sick" isn't the same as thriving? Binary thinking isn't very helpful on issues like this, and it's hard to believe you're arguing in good faith when you say things like this as if you've made a substantive point.
> Perhaps you ought to rethink your priors.
Which priors are those - that I don't want foreign substances accumulating in my brain, much less most brains on the planet?
Why would I? This is a plausibly catastrophic scenario, and you've brought absolutely no evidence that it isn't. None. At all.
> maybe the answer is that it doesn't matter that much, and you're exaggerating the impact.
I don't want to roll the dice on this one, and I think that's the only sensible approach. We have all sorts of alternatives; they're just not quite as 'cheap'.
People have posted elsewhere in the thread about a growing body of scientific links between nasty health outcomes and higher levels of microplastic in people's fleshy bits. You ignored that though... Why? ... Do you have a vested interest? Are you scared that this could actually be an issue, and you don't want to face it? What are your priors - that if you haven't keeled over yet then you're healthy?
> maybe the right answer really is that "0 is the right number"
It is. There's no conceivable advantage from having more than that.
> maybe the answer is that it doesn't matter that much, and you're exaggerating the impact
It's baffling to me that anyone would assume that it's fine and dandy that we're finding increasing amounts of plastic in human brains, or even deny it. To me, that's a ludicrous leap of faith; requiring an utterly unhinged level of naivety or optimism.
> maybe ... you're just panicking.
... You remind me of that old cartoon about climate change - "What if it’s a big hoax and we create a better world for nothing?"
The correct amount of brain plastic is 0 grams. Zero. This is a problem and it's very clearly getting worse.
Why would I have to explain that to someone with a PHD in biology? So weird.