One of the biggest reason plastics are used is because they're inert.

in this case, fluorescent polystyrene particles

Did they neglect any effects of the fluorescent dye instead?

The fact that plastics are everywhere, and we have been exposed to them for several generations, should be seen as evidence of their harmlessness; we would've seen many obvious effects if they weren't. I see this as very similar to the sometimes argued link between cellphone radiation (or RF in general) and cancer.

This is simply more fearmongering from those who stand the most to profit from it...