That's one of my pet peeves on hn, the comments on microplastics studies, or I guess any in-progress science in general. If it's a study on the level of microplastic contamination the environment, or levels and sources of exposure, or to what extent it enters the body, people complain that we don't know yet if they cause harm. When is a study on potential harm, people complain that other substances might also cause harm. They complain generally that the studies don't have total answers, without understanding that this is how science gets us to the big picture.