If this were true, then there would be higher than normal rates of autism within suspect water system districts. Did anyone even suggest this or offer data showing incidents of autism spiked in certain areas? Didn’t think so.
It sure doesn’t look like it and the level of chemicals given to animals could only be found is some water in China.
Yes. That has been done for more than a decade...articles like this and this provide information on it.
Of course, epidemiology and risk assessment can be difficult. You can't just say "a certain area" because there can be multiple factors involved, and teasing them all out is an immense effort. It's easy to come up with hypothetical examples, such as...
...let's say a chemical causes problems in children who also are deficient in Vitamin D. The problem might show up in one town, but another town down south might show no spike. Perhaps they then think it's just the vitamin D...until they find that there's no spike in another northern town. Or there is, because of air pollution. Or...