While atrazine is not an estrogen mimic, the results of some studies suggest that atrazine may affect breast cancer risk by disrupting certain hormonal pathways in susceptible laboratory animals.

We do know there are two hormonal pathways that are affected. Atrazine can decrease levels of luteinizing hormone, and increase levels of a hormone called prolactin. Both of these hormones are important for reproduction in laboratory animals.

Disruption of these two pathways can lead to hormonal changes that increase the number of breast tumors in certain strains of atrazine-treated female rats.

However, many scientists feel that these two hormonal pathways may not be as important in human breast cancer. For instance, elevated prolactin levels are known to increase the number of mammary tumors in rats. However, prolactin levels have little influence on the development of human breast cancer.