What is the evidence that atrazine affects the risk of mammary cancer in experimental animal studies?

Atrazine was fed at high levels over long periods of time to female rats in several studies. Atrazine caused a higher number or earlier appearance of mammary tumors in one type of female rat.

But not all types of laboratory animals were affected.

In other strains of rats and in mice, atrazine treatment did not induce breast tumors.