New research to be published in May 2007 shows that frogs are much more sensitive to hormone disrupting environmental pollutants than was previously thought. Frogs from Africa and Europe were exposed to estrogen or estrogen mimicking chemicals similar to those found in the waters of Europe, the US, and Canada. The results were startling: while the percentage of females in the control groups was under 50%-normal among frogs-the tadpole sex ratios in these contaminated waters were very skewed. Even those tadpoles in the waters with the least of the hormone were twice as likely to become females. The tadpoles receiving the heaviest dose were 95 percent female and in one case100 percent female! Some of the sex-altered males became fully functional females, while others were sterile.
Amphibians are declining at an alarming
rate worldwide, and many scientists believe man-made chemicals such as pesticides
may be partly to blame. The environmental impact of endocrine disrupting chemicals
has been well established. In addition to frog deformations there are polar
bears with penis-like stumps, panthers with atrophied testicles, and intersex
fish. These are all probably "canaries" in the coal mine for likely
*Beyond Pesticides, Technical Report: 22(4), April 2007.