Well your a trained scientist (as am I) so you actually have an understanding of biological systems that other people don't. I agree that the EPA or FDA cutoff

Well your a trained scientist (as am I) so you actually have an understanding of biological systems that other people don't. I agree that the EPA or FDA cutoffs give a false sense of risk. If an acceptable limit is set at 50 ppm, then 49 ppm will pass and 51 ppm will fail. The actual biological impact between the two? Impossible to measure. Hell, the instruments and sampling technique used in testing likely have an accuracy of +/- several ppm.