Obviously parent post is not making the point you're trying to argue, only making the point that the measurement is flawed. If you are going to address their argument do it in good faith and address the strongest point. This isn't reddit
I did address their point. The tendency with climate change, micro plastics, etc. is to deny, deny, deny, until it is too late. Perhaps we should err on the side of caution. In this situation its much better to err on the side of being overly cautious.
Experts wrote the research paper. Until otherwise demonstrated I will give them, the experts, the most generous interpretation per site guidelines. The experts addressed the concern by OP but OP calls it “brushing off”.
People can nitpick anything. The question remains, just how much microplastics are OK? If the answer is small then the study has merits despites its alleged issues.