June 22, 2010
Wastewater Gender-Bending Problem Fixed
According to US researchers on Monday, a Colorado wastewater treatment plant has received upgrades to help filter out gender-bending chemicals that were affecting fish.
The researchers said male fish are now taking longer to be feminized by so-called hormone disrupters in one Colorado creek after improvements to a Boulder wastewater treatment facility was done in 2008.David Norris of the University of Colorado at Boulder had earlier found ethinylestradiol, a female hormone used in contraceptives, in Boulder Creek. His team had also measured bisphenol A and phthalates, which can mimic the effects of hormones. Pesticides and antidepressants have also been found.
Norris, talking at a meeting of the Endocrine Society in San Diego, said the most of the substances probably came from products flushed down drains and toilets.
"We excrete natural and synthetic estrogens and use shampoos, detergents and cosmetics containing a variety of hormone disrupters that wind up in waterways," he said in a statement.
"Our bodies are being exposed every day to a variety of chemicals capable of altering our physiological development, including impacts on sensitive human fetuses," he noted.
For years people around the United States, Britain and elsewhere have reported strange changes in fish and amphibians -- for instance, male fish with female sex organs.
Norris and colleagues took fish from Boulder Creek and placed them in a tank filled with water from their natural sources and the outflow from the wastewater treatment plant before it was upgraded.
After only seven days, adult male fathead minnows became feminized, looking and acting like females and also had elevated levels of a protein known as vitellogenin that is produced by females.
They repeated the experiment after the upgrades were made to the facility. It took a full month before they saw any effects on the minnows in a tank containing 100 percent treated wastewater directly from the plant.
Norris said that the upgrade was fairly simple. "It was simply a planned change from a trickling filter process to an activated sludge process which is more efficient."
"Both systems are in use throughout the country, but the trickling filter process is not efficient enough for a city the size of Boulder (hence the need for the upgrade)," Norris told Reuters through an email.
"It is not clear yet how the chemical concentrations of the estrogenic hormones were reduced, only that both our chemical data and biological data indicate considerable reduction in the estrogenic nature of the effluent," he said.
Norris noted that rainfall and snowmelt may also affect the process and does not necessarily help. They may wash contaminants through the plant faster than normal and drain them directly into the creek.
"Our testing has been done at low flow in the summer when the system is rarely diluted by rainfall and is 50-80 percent effluent," he added.
Image Caption: A mobile fish lab on Boulder Creek is helping researchers assess the health of fish exposed to endocrine-disrupting chemicals polluting the waterway that can cause male fish to be feminized and decline in numbers. Credit: Image courtesy Alan Vajda, University of Colorado Denver
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