

I just pulled this out from my ass, but I would guess yes, they do. But you rinse your mouth after brushing your teeth so I would guess it’s not that bad? Since you’re (mostly) not ingesting the microplastic particles from the toothbrush. But again I’m going off of nothing.
To people thinking of enforcing UTC around the globe:
obligatory: https://qntm.org/abolish
Before I read this article, I also thought it would be a great idea to get rid of timezones entirely and just use UTC for everything. To quote from the link,
(copied from one of my 9-month old comments)