Why do you think there are no federal regulations governing the amount of PFAS/PFOAS allowed in drinking water?

One possible reason is that the adverse effects of PFAS/PFOAS on human health and the environment were not well understood until recently. It is possible that the scientific research on these chemicals has not yet provided sufficient evidence to warrant the establishment of federal regulations. Additionally, some industries may have resisted regulation to avoid the cost of implementing more stringent controls. However, some states have taken action to establish their own regulations on PFAS/PFOAS in drinking water.