Though less obvious than gender bending, immunosuppression could play just as large a part in the worldwide decline of amphibians, which have porous skin and easily absorb chemicals from rain, groundwater and even water vapor. “Numerous studies have documented the effects of environmental pollutants on the amphibian immune system. Nearly all of these studies suggest that amphibians are particularly sensitive,” wrote Tyrone Hayes, a University of California, Berkeley biologist, in a paper published in the March 15 Journal of Experimental Biology. “In particular, the widespread herbicide atrazine impairs immune function and increases disease rates.”
Hayes is also an author of a March 1 Proceedings of the National Academy of Sciences study on the developmental changes wrought in male frogs by groundwater atrazine concentrations regularly found in the United States, where 80 million pounds of the herbicide are used every year. The frogs had low levels of sperm and testosterone; some even produced estrogen, developed female reproductive organs and were ultimately impregnated by their former gender mates.