This is certainly one of those, wow!, who would have thought?
Effluent changes gender of fish
By BOONSRI DICKINSON and TODD NEFF
Scripps Howard News Service Tuesday, December 12, 2006
In 2004, David Norris reported that fish just below the Boulder, Colo., Wastewater Treatment Plant's outflow pipe were changing sex.
Two years later, the University of Colorado integrative physiology professor has expanded his study, which now involves one "Fish Exposure Mobile" research trailer in operation and a second on the way.
Science done in the trailer has verified Norris' 2004 study and shown that surprisingly low concentrations of treatment-plant effluent can change male fish into females.
The 2004 study showed that certain chemicals from pharmaceuticals and personal-care products made it through the Boulder Wastewater Treatment Plant and into Boulder Creek. Ninety percent of the white suckers swimming downstream of the plant were female. Upstream, there was an even split.
"What we see in the fish downstream is as if they are taking birth control pills," Norris said.
The female fish -- both the transsexuals and the original girls -- had smaller-than-average ovaries. The remaining males produced less sperm, showing the water effluent also has contraceptive effects, he said.