Rob Denkhaus
Fort Worth Nature Center & Refuge
Drug found in area fish stirs concern
By Scott Streater
Star-Telegram Staff Writer
Researchers at Baylor University have found traces of an antidepressant in the
livers, muscles and brains of bluegills in a Denton County creek, raising
concerns about the welfare of the fish and the people who eat them.
The chemical, fluoxetine hydrochloride, is the active ingredient in Prozac. It
likely came from a city of Denton wastewater treatment plant, which discharges
into Pecan Creek and flows into Lewisville Lake. Traces of the drug that are
not absorbed into the body can flow down the toilet and through wastewater
treatment plants, which are not designed to filter out pharmaceuticals.
Fluoxetine and other antidepressants affect fish in roughly the same ways they
affect people, said Bryan Brooks, a Baylor toxicologist who led the study.
It relaxes them.
"Maybe it makes you a happy fish and you're kind of hanging out," Brooks said.
"But how does that influence your ability to capture prey? Do you instantly
become candy for largemouth bass because you're accumulating large amounts of
Prozac in your system? These are areas where more research is needed."
Brooks will present the results of his study next month in Austin at the
annual meeting of the Society of Environmental Toxicology and Chemistry.
It's believed to be the first study to determine that antidepressants in the
water can accumulate in biological tissue, raising the possibility of
long-term health and behavioral problems in fish, said Marsha Black, an
aquatic toxicologist at the University of Georgia at Athens.
"That's really a significant finding," said Black, who's using a federal grant
to study the health effects of fluoxetine and other antidepressants in fish.
"This opens up the door and says these things are important."
Eli Lilly and Co., which manufactures Prozac, has a material safety data sheet
for fluoxetine hydrochloride on the company Web site. Under environmental
information, the data sheet states that the chemical is "moderately toxic to
fish and highly toxic to invertebrates and green algae" and can be considered
persistent in the environment because of its low rate of biodegradation. The
data sheet also states that the chemical has low potential to accumulate in
aquatic organisms.
Brooks' latest research comes on the heels of recent studies he helped conduct
while a graduate student at the University of North Texas. That research
indicated that some male fish in Denton County are developing female
characteristics because estrogen from prescription drugs is winding up in the
water. The estrogen -- from birth control pills, hormone replacement therapy
and other sources -- could reduce the fish population by rendering some males
unable to breed.
The issue has garnered national attention in the last few years. In a U.S.
Geological Survey study last year, 80 percent of the 139 streams sampled in 30
states, including Texas, contained small amounts of pharmaceutical drugs,
hormones, steroids and personal-care products like perfumes.
"It's very common," said Herbert Buxton, coordinator of the Geological
Survey's Toxic Substances Hydrology Program. "What this tells us is that these
wastewater pathways are worthy of a lot more study."
Brooks' study raises a number of questions. Among them:
* Can these pharmaceuticals pollute drinking water supplies?
* What are the health effects of eating fish contaminated with
pharmaceuticals?
* If fluoxetine is in the bluegills in Pecan Creek, might it also be in the
tissues of other species in other waterways?
Brooks said he has expanded the research to include catfish and black
crappie.
He said Pecan Creek was chosen as the site of his study because it receives as
much as 13 million gallons a day of treated wastewater from Denton's Pecan
Creek Water Reclamation Plant.
During the dry summer months, the wastewater from the plant comprises all of
the creek's water flow, said Kenneth Banks, Denton's water resources programs
manager.
Brooks said the pharmaceuticals in the creek are coming from the wastewater
plant.
"I think it's got to be," he said.
Pecan Creek drains into Lewisville Lake, which supplies drinking water to the
cities of Dallas, Denton and Lewisville. But researchers say it is extremely
unlikely that the antidepressant could get into the drinking water supply, in
part because the wastewater plant is several miles away from the lake.
"After that distance, it's virtually impossible that it would show up in
potable water supplies," Banks said.
Federal and state environmental regulators do not regulate pharmaceuticals in
water supplies because they have not been proven to harm fish and other
aquatic life.
But the findings of Brooks and other scientists could change that policy. The
Environmental Protection Agency is evaluating the need for formal
recommendations for disposing of old drugs to keep them out of the water
supply. The Food and Drug Administration is studying similar action.
If it can be confirmed that pharmaceuticals are moving untreated through
wastewater plants, sewer plant operators could be required to begin
controlling these discharges. That could necessitate the addition of new
technology costing millions of dollars and could have a tremendous impact in
North Texas.
The Trinity River basin, which runs from north of Fort Worth-Dallas to near
the Houston metropolitan area, is the most developed watershed in the state,
with numerous large wastewater treatment plants.
The Trinity River Association, a public utility created by the Legislature in
1955, operates four large wastewater treatment plants in North Texas that
discharge into the watershed.
"It's very early, but the implications are potentially serious," said Richard
Browning, senior manager of the Trinity River Association's planning and
environmental management division.
"If they come out with a clear connection, then everybody will be looking at
how to get it out of the water. Then the regulations would flow very
quickly."
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