The fact that they have always been around suggest that there is no change to us as a result of their introduction. Plastics, however, have not always been around...
put another way: would you go out and smoke cigarettes and expect no additional harm, because you are already exposed to environmental pollutants?
The study shows that microplastics may block. It doesn't show that micro-natural-substances may not also block.
I'd like to see more actual science, and less fear mongering.
Besides, if other microparticles are dangerous, I’d rather not have even more of those, especially ones that haven’t been through thousands of years of human evolution.