I am also very good at winning made-up conversations.

I think this is kinda the plot of Megamind.

You'd be surprised. Most people would be more inclined to do something evil if asked by someone they trust, and you may have more trust in someone who speaks your language.

This sentence has never been uttered honestly.

The problem there is confounding factors. Microplastic exposure is largely based on geography and socioeconomic class, which are both heavily correlated with health outcomes and have been since before microplastics.

Basically, we don't know. The problem is we haven't found any population of humans without blood microplastics, so we can't compare a population with them to one without.

If there are ill effects, they seem to be small, considering life expentancy has continued to rise across the globe despite the increase in microplastics (with a hiccup due to Covid). Possibly a study could be made that compares a population of animals raised on a very specific, filtered diet free of microplastics to one that receives the same diet but unfiltered (and perhaps even a third population with a diet that is deliberately laced with higher doses of microplastics). No guarantees that this will translate to humans, but it would be a start. In any case research is ongoing.