As a result of the similar hormones and similarities in functions, atrazine predictably has similar effects across wildlife species and laboratory animals. The results in animal studies predict effects in humans, which cannot be studied experimentally. Atrazine has been linked to spontaneous abortions in humans . Atrazine not only reduces sperm production in fish, amphibians, and laboratory rodents, but is associated with impaired fertility and low sperm counts in humans . The induction of the mechanism for depleting testosterone and converting it into estrogen (increased expression of the enzyme aromatase) was, in fact, discovered originally in human cancer cells [3-6] and tissues, and has been characterized in great detail [7, 8]. Further, similar to atrazine’s induction of prostate cancer and mammary cancer in laboratory rodents, men exposed to atrazine in a Syngenta production facility in Louisiana developed prostate cancer at 8.4 times the rate of unexposed factory workers [9, 10] and women whose well water was contaminated with atrazine were more likely to develop breast cancer when compared to women who lived in the same area, but who do not drink well water . Most significantly, the importance of atrazine’s induction of aromatase and its relationship with breast cancer and prostate cancer, is best appreciated when one considers that Novartis, the same company that made atrazine (an aromatase inducer) now markets the chemical, letrozole (an aromatase inhibitor) for the treatment of breast cancer and prostate cancer .
Further, as studies in laboratory rodents are conducted to allow us to better predict effects in humans, concern is raised regarding several aspects of public health. Based on studies in laboratory rodents and the association between atrazine and the conditions described above, atrazine is likely involved (but not necessarily the only factor) in decreased fertility in both men and women, increased spontaneous abortion rates, decreased birth weight, and prenatal and adult exposure is likely linked to increased breast cancer and prostate cancer rates (the two most common cancers in women and men, respectively). Furthermore, also keep in mind that many of the studies showing the inhibition of immune cells (including the cells that kill cancer) by atrazine were conducting using human cells. Given that approximately one million people per day and 60% of all Americans are exposed to atrazine, this is a concern.
7. Reproductive Cancers