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Pharmaceutical byproducts a health wildcard in San Marcos River


The city’s wastewater treatment plant was successful in removing nearly all of the 18 chemicals known to interfere with natural hormone production that a research team detected in the sewage system.

But trace amounts of certain unregulated chemical compounds known as “endocrine disruptors” are being discharged into the San Marcos River with effluent from the wastewater treatment plant, according to the city-funded study by Texas State University and the Edwards Aquifer Research and Data Center.

Three times since November, Adam Foster, an aquatic biology graduate student, collected samples from each stage of the wastewater treatment system and from up- and downstream of where treated water is released into the San Marcos River.

Fourteen chemicals found in common consumer products from plastics to perfume to pharmaceuticals were prevalent enough that they were found in all three sample periods. Twelve of them, albeit often in relatively tiny amounts, were detected in samples taken downstream of the discharge point including Diltiazem, an antihypertensive; Tris(2-chloroethyl)phophate, a chemical common in fire retardant; triethyl citrate used in fragrances; nonylphenol, a detergent metabolite; caffeine; and coprostanol, a fecal steroid.

“That is not to say that we have concentrations in our water supply or river that are at the level where we know them to be harmful. A lot of people think about environmental contaminants in terms of individual exposure to one of them. The bigger problem is the combined effect of all the different exposures,” said Glenn Longley, the aquifer research center director who oversaw Foster’s work on the study.

A term used loosely to describe a range of synthetic or natural chemicals that interfere with the endocrine system which regulates growth and reproduction, endocrine disruptors are a relatively new field of study and as yet are not regulated by the Environmental Protection Agency. Early research, however, indicates that even exposure to tiny amounts can have disturbing effects on animal growth and reproduction. One study of the Potomac River indicated that pharmaceuticals are a possible cause of fish with essentially crosswired sexuality, including males that produce eggs.

“Nobody wants to say it but these chemicals could affect human reproduction with enough exposure if it’s effecting these creatures that live in the water,” said Dianne Wassenich, the San Marcos River Foundation executive director. She said the study is “big news nationally, maybe internationally, as people become more aware of this issue.”

Foster’s study is one of the first that examines the effectiveness of different processes at the wastewater treatment plant at removing the chemical compounds. In most cases, the aeration process was critical to their eradication. Overall, the wastewater treatment plant removed 99.9 percent of the tested endocrine disruptors by mass.

“In many places, this stuff is put into waterways with virtually no treatment. We are fortunate that we have a very good treatment facility here but it is increasingly being recognized as a problem across the country. We’re finding that this stuff is ubitiquous because we take so many drugs and use so many processed chemicals in our society. It’s becoming more important to understand how this affects human,” Dr. Longley said.

When the federal government does begin regulating endocrine disruptors, “we’ll be able to show that we are already addressing the issue,” said Tom Taggart, the city’s water and wastewater department manager. That does not impact at least a dozen other cities and industry that discharge effluent in the San Marcos River or its tributaries.

One quirky find of the study: Chemicals commonly used in fragrances were found in untreated water at much higher concentrations than studies of municipal wastewater system conducted by the U.S. Geological Survey. Longley said, “We think that’s probably because this is a college town and young people use a lot of perfumes and colognes and things like that.”

This story by Brad Rollins was originally published in the San Marcos Daily Record on August 11, 2007.