Sewage Effluent Affects Fish
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.The chemicals are believed to come from excreted birth-control hormones, natural female hormones and detergents flushed down toilets and drains. In the ecosystem, they are known as endocrine disrupters, settling into cell receptors intended for hormones and garbling the body's chemical communications.
To bolster his evidence, in 2005 Norris and colleague Alan Vajda, a CU research associate, set up the Fish Exposure Mobile in a trailer borrowed from the Colorado Division of Wildlife. U.S. Geological Survey scientists Larry Barber and James Gray also are working with Norris' team, and the city of Boulder's cooperation also has been vital, the scientists say.Where Norris and Vajda are what Barber called "world-class endocrinologists,"
Barber and Gray are chemists who have advanced detection techniques to the point they can spot human estrogen in concentrations as low as 0.2 parts per trillion.They needed such exactitude because human estrogen, or 17 beta estradiol, affects fish at concentrations as low as one part per trillion - the equivalent of a pinch of salt in an Olympic pool, Norris said.Barber said volumes of human estrogen in the pure treatment-plant effluent range from one part per trillion to about 10 parts per trillion.
The Fish Exposure Mobile, parked next to the creek on sewage treatment plant property, pulls water directly from the plant's outflow pipe and can dilute it using precise volumes of upstream Boulder Creek water.Fathead minnows swim in two identical tanks inside, each 200 gallons. One fills with upstream creek water; the other with varying degrees of wastewater plant effluent. Such control lets researchers see how fish react to varying effluent concentrations.They aimed to create a controlled experiment and confirm if estrogen and other compounds from the treatment plant were responsible for the fish sex change.
"The males were feminized in seven days," Norris said. "You don't need a Ph.D. to sex them."The males have bumps on the forehead and often attack each other. The fish exposed to the effluent water lost their bumps and acted like girls. It confirmed effluent to be the culprit.
Diluting the treatment plant's effluent 50 percent feminized breeding male fish in a week to 15 days, Norris said. Some of the effects remained evident even when the wastewater plant effluent was diluted 75 percent.
"We were excited to get these results, but at the same time we're a little bit appalled at what we've seen," Norris said.Sheila Murphy, a hydrologist with the U.S. Geological Survey in Boulder, said the Fish Exposure Mobile work has been important to counter skeptics who attribute transsexual fish in the Potomac River and other waterways to temperature changes or other environmental influences.
"What it's showing is that it's indeed from the wastewater plant," Murphy said.
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