[parentheses]

I agree with your question:

> whether the exposure you'd receive from occasional microwaving would be enough to ever cause any meaningful health problems

Another question worth asking:

How much of the ~20 ng/kg/day makes its way to the kidney cells? Said another way, if one were to consume a liquid concoction with a certain concentration of nano/micro-plastics, what would the total negative effect be? How much would simply be excreted? That answer for babies vs adults may also vary.