https://phys.org/news/2019-10-nanoparticles-bigger-impact-environment-previously.html I remember hearing about this a very long time ago, comparing nanoparticles to asbestos. Since then the amount we use just seems to go up every year. As well as our understanding of how potently harmful they could be. I can see this becoming like the problem of plastic in the oceans where the problem will become dire before any action is taken.