Remember how they explained spontaneous sex change in Jurassic Park? It had something to do with environment and population ratios and pixy dust. Well a recent study by a lab in Sweden suggests that certain environmental pollutants can cause male frogs to turn into female frogs. The research group exposed two species of frogs to estrogen at levels similar to those detected in natural bodies of water in Europe, the U.S. and Canada. The percentage of females in two control groups was under 50% (normal frog ratio). The sex ratio in three pairs of groups maturing water dosed with different levels of estrogen where greatly skewed. The group receiving the highest dose of estrogen had 95% turn female. No wonder a third of frog species are being threatened with extinction.

Environmentalists have always used frogs as a divining rod for pollutants. A similar study in the U.S. found that a pesticide that produced estrogen-like chemicals had the same effect on Rana pipiens male frogs. Certainly if all the frogs turn female, that’s it for frogs, but look at the bigger picture. If it effects frogs now, how long until we see a major effect on humans?