Misconception: Cancer risks to humans can be assessed by standard high-dose animal
cancer tests. In cancer tests, animals are given very high, nearly toxic
doses. The effect on humans at lower doses is extrapolated from these results,
as if the relationship were a straight line from high dose to low dose.
However, the fact that half of all chemicals tested, whether natural or
synthetic, turn out to cause cancer in rodents implies that this is an artifact
of using high doses. High doses of any chemical can chronically kill cells
and wound tissue, a risk factor for cancer .
"Our conclusion is that the scientific
evidence shows that there are high-dose effects," Ames says. "But
even though government regulatory agencies recognize this, they still decide
which synthetic chemicals to regulate based on linear extrapolation of high
dose cancer tests in animals."