That's one. And as I mentioned above, the uncertainty factors are pretty wild. Because some individuals within a species may more vulnerable to a toxic than t

That's one. And as I mentioned above, the uncertainty factors are pretty wild. Because some individuals within a species may more vulnerable to a toxic than those tested, the standard practice is to move the decimal point for the lowest/no observed effect dosage one place to the left. And when you're using animal studies, it's standard practice to account for inter-species variability by moving the decimal point to the left another digit. If your data was at all suspect, they will apply another uncertainty factor (though usually less than a full order of magnitude). And always, the adjustment is in the direction of being more conservative, notwithstanding the fact that humans are frequently more resilient to toxic exposures than small animals, not less. An order of magnitude is a big deal when dealing with very small exposures. Two orders of magnitude starts to become completely unmoored from reality. How conservative we are in the face of that intra/inter-species uncertainty is couched as "science," but it is TOTALLY a policy call. And it has real world impacts. For large manufacturers, an adjustment factor of half that much frequently means the difference between no pollution controls and tens (if not hundreds) of millions of dollars in pollution controls. I find that where you land on that uncertainty has nearly perfect correlation with your politics.