Las Vegas Sun

July 28, 2017

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Chemicals cause changes in fish and raise concerns for humans

There's something wrong with the fish.

It's been confounding scientists for years: Male fish are developing female sexual characteristics in Lake Mead and other freshwater sources around the country.

On Thursday, the U.S. Geological Survey released a four-page summary of more than a decade of studies linking wastewater chemicals to those changes.

But a scientist who has studied the issue for years complains that the report understates the danger of those toxins at Lake Mead and elsewhere. The researcher had aired his concerns seven months ago - shortly after he was fired by the USGS.

The federal agency says the researcher was fired for failing to publish his data. The researcher says the federal agency wouldn't allow him to publish.

Both sides, however, agree on the basic issue: In Lake Mead and in other freshwater sites, scientists have found traces of pharmaceuticals, pesticides, chemicals used in plastic manufacturing, artificial fragrances and other substances linked to changes in fish and animals. Thursday's report noted that the primary source for the chemicals in Lake Mead was the Las Vegas Wash, a man-made river made up almost entirely of treated wastewater from cities in the Las Vegas Valley.

Lake Mead is the source of 90 percent of Las Vegas' drinking water and provides water for millions more people in California and much of the winter vegetables produced in the United States. The lake and contamination have been the subject of intense scrutiny from federal and local scientists.

One of those scientists studying Lake Mead was Tim Gross, who was the federal lead researcher on the lake's issue of emerging contaminants until he was fired earlier this year by the USGS. Gross, a researcher and teacher at the University of Florida , said he was terminated because the government didn't like his research conclusions - namely, that hormone-disrupting chemicals are prevalent in Lake Mead and affecting the environment to a greater degree than once suspected. Federal officials in April said Gross was fired for failure to publish research results and a new team of scientists would evaluate Lake Mead data and publish the results.

The Thursday report, which suggests more research is still needed, was the product of the new team, a summary of research by a number of scientists. It did not include Gross' results.

Gross, meanwhile, is still battling the federal government.

"They (federal officials) refuse to let me be involved in the research. They still haven't published the data. They don't want us to publish."

Kimball Goddard, state director of the Nevada-U.S. Geological Survey water science center, rejected the allegation that data had been suppressed.

He said research data from Gross was not included in the fact sheet released Thursday because the Florida scientist's results were not published.

Gross said the problem is acute in Lake Mead and in other freshwater sites. One element left out of the Thursday report is evidence of sperm failure in fish, he said.

"On a national scale we see alterations in fish," said the scientist, who continues to research hormone-disrupting chemicals in Florida and other states. "Endocrine (a hormone) disruption is widespread across the United States and is widespread in Lake Mead."

Gross said his conclusions, shared by other researchers, are not popular: "The (Southern Nevada) Water Authority doesn't want to hear it. My agency doesn't want to hear it The Department of Interior does not want to deal with it. They want to make the argument that there is nothing to worry about, but common sense just suggests it is not that simple."

Gross, echoing comments he made in the spring, said he is concerned that there could be effects to human health from hormone-disrupting chemicals in Lake Mead.

"There are huge implications, and they're treating it like there's a little preliminary work and the significance of these effects are unknown," Gross said Thursday. "I would disagree with that. They don't discuss the possibility of human exposure. The potential for that is real, and they don't discuss that."

Goddard said the implications for human health are outside the realm of the Geological Survey's work.

"The studies that we have been involved in at the USGS are not designed to answer those kinds of questions," he said.

Gross and the federal researchers have found sexual abnormalities in carp, bass and the endangered razorback sucker. The problems are higher in Las Vegas Bay, at the confluence with the wash, than in other reference points in Lake Mead.

Studies documenting sexual abnormalities in fish in the Potomac River - source of drinking water for millions in the Washington, D.C., area - raised similar concerns in September. Water officials there said the studies showed no evidence that drinking water was unsafe, but the studies did not answer the question on potential impacts to human health.

Water Authority officials maintain that while chemicals from the waste stream flowing through the sewers and Las Vegas Wash to the lake could affect fish and the environment, drinking water drawn from the lake is sufficiently treated to eliminate any significant threat to human health.

Shane Snyder, the Water Authority's principal researcher on the issue, said Thursday at a conference of the American Society of Mechanical Engineers that people are exposed to far higher levels of most hormone-disrupting chemicals in the environment than they would receive from treated drinking water.

He asked rhetorically whether it was good policy to spend "trillions of dollars" removing hormone-disrupting chemicals from water when such chemicals are present in far larger amounts in the environment.

Snyder said the central question of the "toxicological relevance" of chemicals in tiny quantities - amounts that were undetectable just a few years ago - has yet to be answered.

J.C. Davis, Water Authority spokesman, noted that even in Lake Mead itself, the quantities are minuscule - in the parts per trillion, a grain of salt in a swimming pool. Treatment processes further degrade, destroy and dilute these chemical compounds in drinking water.

"Eventually the analytical ability outpaces the health effects," Davis said. "The question is, at what concentration are these relevant and you have to do something about them?"

He said Snyder will join federal and local researchers in trying to find those answers.

"People in the water industry want to know the answers to the questions we are asking."