Common herbicide found to sexually alter and chemically castrate male frogs
March 2, 2010
(Chattahbox) – After years of speculation on why frogs and other amphibians populations have been diminishing a new study seems to implicate a common weed killer used globally. A study published Monday in the Proceedings of the National Academy of Sciences (PNAS), showed that the herbicide Atrazine, used primarily on corn crops, causes chemical castration in frogs and could be contributing to a worldwide decline in amphibian populations. While previous work has shown Atrazine can cause sexual abnormalities in frogs, this new study has stronger implications to frog populations. Researchers compared 40 male control frogs with 40 male African clawed frogs reared from hatchlings until full sexual maturity, in Atrazine concentrations similar to those experienced year-round in areas where the chemical is found and below levels that the U.S. Environmental Protection Agency considers safe for drinking water.
At the end of the experiment, while all frogs in the Atrazine-free group remained male, ninety percent of the male frogs exposed to Atrazine had low testosterone levels, decreased breeding gland size, feminized laryngeal development, suppressed mating behavior, reduced sperm production and decreased fertility.
Meanwhile the remaining 10 percent of Atrazine-exposed male frogs developed into females that copulated with males and produced eggs. The larvae that developed from those eggs were all male, according to the study by researchers at the University of California at Berkeley, which further skews the population sex ratio. Atrazine mimics a biological compound and increases the production of estrogen. It has been shown to disrupt hormone levels in other animals as well as in human cells.