Thursday, September 07, 2006

Effluent tipping scales on fish gender

A landmark study has found that wastewater from sewage-treatment plants in Boulder and Denver is causing gender deformities in suckers living downstream.
By Katy Human Denver Post Staff WriterDenverPost.com

Wastewater pouring from sewage-treatment plants in Boulder and Denver is bending the gender of fish living downstream, a new study has found.

Some of these strangely sexed sucker fish have male and female organs, and others have sexual deformities, according to a study by University of Colorado researchers.

"It's sort of a sentinel for us," said David Norris, a CU biologist and an author of the report. "Every major city in the Western U.S. is looking at it."

The paper, published this month in the journal Comparative Biochemistry and Physiology, is the first peer-reviewed study documenting the reproductive problems of fish downstream from Colorado wastewater-treatment plants.

Similarly odd fish have been found in England and in the Potomac River in Washington, D.C., Environmental Protection Agency officials said.

Although gender-deformed fish have been found in Front Range streams in the past few years, skeptics argued that any number of pollution sources - even natural effects - could be the cause.

The CU scientists now say they've confirmed that wastewater effluent is to blame.

The new results raise concern about whether the stuff people dump down drains - from urine to cleaning products to cosmetics and medicines - can alter the hormonal systems of other animals, researchers said.

Healthy male minnows placed in diluted effluent from Boulder's treatment plant stopped making sperm within two weeks, said Alan Vajda, a CU research associate and another author of the new report.

Many Colorado cities and towns pull drinking water from creeks downstream of wastewater-treatment plants.

There is, however, no evidence yet that the so-called endocrine-disrupting chemicals found in wastewater are concentrated enough to cause significant problems in people, Norris said.

People are bigger than fish, he said, and don't live in water.

"The problem is, that's not the only source of this type of chemical," Norris said. "It's in our food, it's in our plastics, it's in pesticides. ... We're being bombarded all the time."

People eating fish probably aren't at risk of harmful exposure, said Larry Barber, a researcher with the U.S. Geological Survey in Boulder.

Endocrine-disrupting chemicals are at low levels in sucker fillets, Barber said.

Patti Tyler, science adviser for the EPA's Denver office, said, "We're still not clear about ... whether exposure to these compounds has effects on humans."

The CU research team has been given about $800,000 in EPA grants to continue investigating the strange fish maladies downstream from state wastewater-treatment plants, Vajda said.

Other EPA offices are also funding similar work around the country on endocrine-disrupting chemicals in waterways, Tyler said.

Also, the EPA has recommended limits for some of the chemicals, such as the nonylphenols found in cleaning products.

Boulder wastewater-plant officials cooperated with the research, helping set up a mobile laboratory on site.

"It's valuable information not only for Boulder, but for other people in this industry," said Floyd Bebler, the city's wastewater coordinator. "It's happening all over, especially in the effluent-dominated streams ... of the West."

http://www.denverpost.com/news/ci_4297391

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