How come people are concerned about hormones in cow's milk

Aren't they hormones designed for cows, not people? Why would they affect humans at all?

that's faulty logic. after all DDT was "designed" as a pesticide to kill insects in crops. after extensive use, it was found that there was a detrimental effect on wildlife and humans as the dead insects were consumed and passed up the food chain from the residual effect. it's ridiculous to assume that a synthetic hormone has a target and would never affect anything beyond that.

http://www.kleinpeterdairy.com/Main.aspx