The average brain weighs 1300-1400 grams. If 0.5% of that is plastic by weight, your brain contains 6.5 - 7 grams of plastic. The average plastic credit card weighs 5 grams.
https://www.theguardian.com/environment/article/2024/aug/21/microplastics-brain-pollution-health
From my understanding of the study they used an unverified method on a small part of the brain to get the amount of plastic in the entire brain. Which can be misleading because if you only look at the parts of the brain that are microplastics, the brain is 100% plastic. There hasn't been widespread replication of the results yet either nor has the paper been peer reviewed.
I'm sceptical especially with the microplastic doomer narrative going around. As far as I know the danger of microplastics on the human body is yet to be determined. But it's definitely alarming I just don't think it's responsible to be saying there's a credit card in your brain.
That first paragraph is fair enough.
I'd disagree that the microplastic doomer narrative is incorrect, the plastic in the brain is just the newest tidbit. It's already in our kldneys, testicles, placentas, blood, semen, livers and lungs. Even if this study is wrong (which I don't think it is, because its on trend with plastic contamination growth in the rest of our bodies) about how much plastic there is specifically in brains, there's still easily a credit cards worth in our bodies.
Microplastics are killing worms, it is contaminating soil, it is hurting crops, it is killing fish, and studied effects of plastic on other mammals are bad, to the point it seems pointless to confirm it hurts humans in specific ways before doing something about it.