There has yet to be a solid study showing negative health effects from plastic. Yes, it is EVERYWHERE now, and that's definitely not a good thing. But it's not like we have any real signs of it causing disease or cancer.
Unless something has come out in the last year or two, yes it is. There are all sorts of studies showing micro plastics have gotten pretty much everywhere in our bodies, in the soil, in the rain, but no major study has yet to correlate that with any kind of health issues
Humans may experience oxidative stress, cytotoxicity, neurotoxicity, immune system disruption, and transfer of MPs to other tissues after being exposed to them.
I mean, there's a few hints now like the other person posted, but I think it's fair to say we can't say for sure it's comparable to other modern health hazards.