Have we been able to link any real harm to microplastics? I know it sounds bad intuitively. But can we draw a link to any diseases? What if this just amounts to fear mongering?
No but that's a silly standard. I can't go back in time and blood test my infant self. We have microplastics everywhere because of their widespread use. That's been occurring for a few generations now. There is no rational reason to think that we only accumulated them when we first noticed them. No the rational explanation is its been that way as long as we've been mass exposing ourselves to plastics which is right around the end of the second world war. And if car tires are as big of a contributor as some studies indicate then its been even longer because vulcanized rubber is a prewar invention.
Then there is nothing to worry about because everything since WW2 has been fine as far as cognition and general health is concerned. Although, IQs and sperm quality have been declining for a while now but it's probably unrelated to all the plastic pollution.
I think there likely is little cause for concern. Is it contributing to poor health? Maybe but if it is then its a small contribution. There are much bigger issues like poor diet and lifestyle. HFCS for example was easy to link to poor health and it should probably be outlawed.