Traces of drugs found in LV Wash

Monday, Oct. 16, 2000 | 11:23 a.m.

Vegas Wash and the Las Vegas Bay have revealed traces of:

Pill-popping, sun screen-smearing people living in and visiting Southern Nevada are leaving traces of drugs, detergents and DDT in the Las Vegas Wash.

The good news is that the contaminant levels discovered in the wash and the Las Vegas Bay are so low they might not disrupt human health. But scientists are still concerned over what they don't know about the new discovery -- how it might affect the environment and water supplies.

The Las Vegas Wash runs into Lake Mead, where Southern Nevada draws most of its drinking water.

Scientists had found pesticides and detergents in the wash before, but this is the first time the presence of prescription and nonprescription drugs -- as well as one pesticide previously only suspected, lindane -- has been confirmed.

The Southern Nevada Water Authority first guessed drugs may be finding their way into the Las Vegas Valley's wastewater after German and British studies found evidence of prescription and over-the-counter drugs in the water supplies of their countries.

But now research by University of Michigan toxicologist Shane Snyder, hired by the water authority to test the wastewater here, confirms that traces of Valium to Robitussin are being flushed into Southern Nevada's water system.

Only 40 to 70 percent of prescription and over-the-counter drugs are absorbed into the body, which explains the traces of tranquilizers, pain medication, cough syrup and other pharmaceuticals in the wash.

The pollutants are common in surface waters across the United States and Europe, although prescriptions drugs, plastics and fire retardant chemicals are relatively new to the environment.

Several research teams across the United States are looking at the effects of human pollutants that escape the wastewater treatment process, Snyder said.

Snyder started studying Las Vegas wastewater as part of his doctoral work after a U.S. Geological Survey study in 1997 found female egg yolk protein in male carp swimming in Las Vegas Bay. Normally the protein is found only in females.

The Las Vegas Wash study was the first time in North America that human hormones were linked to possible endocrine disruption in fish.

Estrogens pack 1 million times the effect on living things than the detergents found in the wash. Synthetic hormones, such as those found in birth control pills, are more potent in water than natural hormones.

Snyder has studied wastewater from three treatment plants -- Las Vegas, Clark County and Henderson -- to isolate chemicals, pesticides, insecticides and hormones such as estrogen.

DDT, DDE and lindane -- all pesticides -- were found in amounts equal to a drop of ink in a 12 million gallon reservoir. Once water flows into the lake, tests cannot detect the chemicals, because water from the Colorado River dilutes incoming water from the wash, Snyder said.

On top of all of the potent ingredients in the wastewater, chemical plants in Henderson have been producing metals, insecticides and pesticides since the 1940s, contributing a share of pollutants to the wash, Snyder said.

The amounts of the chemical contaminants indicate they are leaching from the soils into the ground water and entering the wash from less than three miles away, he said.

Scientists have not begun to measure the reactions between drugs, chemicals and other substances, because some of the contaminants discovered in the wash are so new, Snyder said.

The Las Vegas Valley is lucky to have such new treatment plants, he said.

Snyder studied discharges from Detroit treatment plants that are much older than those in Las Vegas and found higher amounts of drugs, detergents and estrogens.

Snyder, working with the federal Environmental Protection Agency in Las Vegas and the Bureau of Reclamation, plans to continue studying the urban runoff into the Las Vegas Wash and the bay.