For endocrine effects, yet another 162,000. And so on. Sometimes low doses are more toxic than high doses, yet this type of study is almost never conducted. The reason appears to be that at higher doses defense mechanisms kick in. Industry almost never does tests to determine low dose effects, so when they say low doses cause no effects in animals, it is almost always because they haven't looked.
People are often more sensitive to toxic substances than test animals.
The dose that caused permanent loss of IQ was only found through tracking of injured children. Chemicals are almost never studied for toxic effects at low doses. Animal tests are conducted at high doses for reasons of statistical power. A low dose effect that occurs in just one out of every 1,000 people could be missed completely by animal studies which use only 500 animals at relatively high doses. An effect that occurred in 1 in 1,000 people would injure 270,000 people in the U.S. population.