There have been several studies to show this. As I understand it has to do with the plastics and plasticizers acting as estrogens (female hormones. ) Although, I wouldn't be surprised if pesticides are involved. Considering what they do to amphibians.
"Atrazine, one of the world's most widely used pesticides, wreaks havoc with the sex lives of adult male frogs, emasculating three-quarters of them and turning one in 10 into females, according to a new study by University of California, Berkeley, biologists."
http://www.sciencedaily.com/releases/2010/03/100301151927.htm







