Most plastic that we use shows evidence of endocrine disruption activity and it isnt just BPA as a byproduct of the manufacture of certain plastics. We know it is bad for the environment too. Microplastics are pervasive and also known to have negative health and environmental consequences.
Don't forget to specify with soap and to do it after bathroom visits and before meals, otherwise they'll just wash their hands once per month and use dirt to wash with.
The answer would probably be something sensible, within our ability and something we would be capable of.
We already know how to do this .... we as a collective global civilization just actively refuse to do any of it unless we were forced to, either by war or by the realization that it will mean our extinction.
It's not that we are a thousand years dumber than our descendants .... we are just as intelligent and insightful as our ancestors a thousand years ago ... it's just that our short sightedness and greed gets the best of us.
In many ways we are still a lot like our prehistoric ancestors from 100,000 years ago who believed that our family should control all the unlimited amount of bananas in the jungle.