One of the challenges is that little is known about the impact of microplastics on human health and the toxic effects that may vary depending on the type, size, shape, and concentration.
I think everyone agrees that microplastic accumulation is not good, but how much effort should we dedicate to eliminating them. Like if we banned plastic food packaging, but used something that increased the risk of food poisoning by 0.001% would that have a net positive impact on our society's health?
Plastic isn't a chemical. It's a weasel word. Microplastic isn't a thing either.
At least the fucking BPA stuff from last decade was a real chemical. But fucking plastic? There's no chemical called plastic.
Now if you want to study the effects of polyethylene and/or polyurethane, sure. Except Polyurethane is better known as glue and paint so good fucking luck getting that out of our houses.
We moved to polyurethane paints because they were probably healthier than lead based paints btw. Where's the proof that the... Next paint chemical whatever it ends up being... Is safe?
Isuppose you're right that there is not a strict definition but I've never spoken with person that didn't understand microplastics to mean something like:
micro particles
(too small for a person to notice ingesting but visible with a magnifying glass or optical microscope)
::: of [solid but easily deformable] hydrocarbon polymers [intended] to be biochemically inert/benign.
Health agencies have historically adjudicated whether particular hydrocarbon polymers are safe for human exposure based on biochemistry (ie are they poisonous?). Assuming that if they were biochemically inert they're safe. But obviously it's unsafe to fill your lungs with inert particles of any size... you'll suffocate. So is it a problem that our blood has unprecedented levels of inert micro particles? It's probably not good. How much can a person ingest before serious issues?
Nobody really knows. Maybe microplastics cause autism, I don't think anybody knows. We'll probably have to do some heinous animal trials to figure it out. And look how much time I've spent talking about something other than climate change.
There is no proof. There is never proof. Moving toward "thing that's probably killing us less" is still worth it imo. It's not uncommon for the solution to one problem to be a cause or catalyst for another problem. That doesn't mean we shouldn't try to solve problems.