[coldtea]

>It reminds me of when everyone was afraid of BPA

That's still the case.

>And what defines a “microplastic”? There’s so many different types of plastics that all have different effects on the body

It's not that hard to constrain it to synthetic organic polymers (aka plastics) that are small enough (smaller than 5.0 mm).

Even if there are some exceptions also considered plastics, this already covers 99% of the ones to worry about.

And the effects we worry about are from the presense of millions of hard synthetic micromaterials like that in the bloodstream, organs, and even the brain.

That's enough of a concern for the whole class, before we start to care about them "all having different effects on the body" (which is barely a given).

[krisoft]

> smaller than 5.0 mm

There are no "millions" of 5mm plastic pieces in your bloodstream. That's about a rice grain. If there would be even a single one between 5mm and 1mm it would cause an almost immediate obstruction.

[coldtea]

What part of "smaller than" was difficult to parse?

Microplastics can be defined as < 5mm (e.g. EPA uses that definition), doesn't mean the larger ones are in the bloodstream, or even less so, the brain.

But such "sizable" ones in the environment can and are be broken down, digested, shed smaller micro- and nanoplastics by the loads, and so on.

[rocqua]

Do you happen to know whether the worry is about the inertness of microplastics, and hence the physical damage of the particles. Or is it in the plastics being chemically interactive with tissue?

[coldtea]

Both cases are considered harmful, the surer and heavier more general case being for the former.

The inertness alone means boost in inflamattion, damaged cells, etc. Just consider that asbestos is biologically/chemically inert too - the issues come from inflammation, scarring, dna damage, etc.

But (and varying per microplastic case on lots of factors: composition, dyes used, etc), the chemical interaction can also play a role.