Weed killer feminizes fish. (Environment).The widely used herbicide atrazine atrazine
a triazine herbicide; it is not poisonous at levels of intake likely to be encountered in agriculture.
atrazine Toxicology A nonphytoestrogenic herbicide. See Phytoestrogen. can convert male frogs into hermaphrodites Hermaphrodites
half-man, half-woman; offspring of Hermes and Aphrodite. [Gk. Myth.: Hall, 153]
See : Androgyny (SN: 11/02/02, p. 275). But what happens when a naturally hermaphroditic species, such as the mangrove killifish killifish, northern representative, especially the genus Fundulus, of the Cyprinodontidae or toothed minnows, a family that includes also the topminnows and many popular aquarium fishes (e.g. , encounters this weed killer?
The hermaphrodites can change into females, new data show.
William P. Davis of the Environmental Protection Agency Environmental Protection Agency (EPA), independent agency of the U.S. government, with headquarters in Washington, D.C. It was established in 1970 to reduce and control air and water pollution, noise pollution, and radiation and to ensure the safe handling and in Gulf Breeze, Fla., and his colleagues put killifish hatchlings in water with atrazine at a concentration of 16 or 33 parts per million parts per million
mg/kg or ml/l; see ppm. for just 5 hours, then raised the fish until they laid eggs.
Ordinarily, these fish develop ovotestes, gonads that make both eggs and sperm. However, 30 percent of killifish exposed to atrazine developed no sperm-producing capacity but still could lay eggs. Davis says this is the first evidence of true adult females in this species.
The finding suggests that atrazine disrupted hormonal cues for testicular tissue. Though mangrove killifish with solely male gonads exist in the wild, they're rare, Davis notes, so the new females' eggs probably would never be fertilized.
The bursts of atrazine exceeded what would ordinarily occur downstream of any farm, Davis notes. His group is now investigating whether longer exposures to more environmentally relevant herbicide concentrations also yield the novel females.--J.R.