The question on how toxic it is is always about the concentration and exposure time. Even the most toxic substances in a low enough concentration is pretty harmless and even absolutely non toxic stuff in high enough concentration can kill you if you are exposed long enough to it.
And the concentration emitted during normal printing, specially in a closed case isn’t really high, same like laser printers who emit quite a bit of dangerous small particals. But usually concentration remains not really high and exposure time tends to be short.
So I think a closed printer with a filter inside the case should reduce toxic materials enough to be non dangerous inside a home. If you plan a whole printfarm in your house, things might change though.