Take common pharmaceutical products, for example. Two years earlier the same researchers had reported breast cancer promotion in rodents fed clinically-relevant doses of antidepressant drugs, which are marketed as Elavil and Prozac. Millions of women in the U.S. are taking these drugs today. A review of 51 studies of women taking hormone replacement therapy showed that those who never took hormones had a breast cancer rate ranging from 18 to 63 per 1000 women. The danger largely disappears 5 years after discontinuing use.
Hormones are big business.
Despite evidence that synthetic hormones caused cancer in rodents and rabbits, American drug companies began selling synthetic hormones in 1934 in cosmetics, drugs, food additives, and animal feed. Three years later, in 1941, NCI published a second study confirming that DES caused breast cancer in rodents. DES is 400 times as potent as natural estrogen and can be made for pennies per pill. It was therefore phenomenally profitable and researchers aggressively sought new uses. It wasn't long before researchers discovered that they could make chickens, cows and pigs grow faster if they fed them hormones, and a huge new market for hormones opened up.