Here's a fish story to top all fish stories: A Baylor researcher has discovered trace amounts of fluoxetine, the active ingredient in the antidepressant Prozac, in fish living downstream from a Texas waste-water plant.
The finding was proclaimed in headlines around the world, but this fish tale doesn't end there. Both the techniques used to discover the contamination and strategies that might be developed to reduce it could someday help protect humans from bioterrorism.
"We turn the faucet on to take a shower every morning. We don't think where the water is coming from. ... We excrete small levels of drugs or flush leftover pills down the toilet and don't think of where it is going," says assistant professor Bryan Brooks, director of the ecotoxicology laboratory in the Department of Environmental Studies and a researcher at Baylor's Reservoir and Aquatic Systems Research Center.
Brooks' findings, which grew out of his graduate work at the University of North Texas, drew international headlines when he presented them at the annual meeting of the Geological Society of America in Seattle in November. The field, known as pharmaceutical and personal care product (PPCP) research, is getting increased attention because strategies to reduce PPCPs in water also might remove toxins released by bioterrorists.
Brooks reported finding small amounts of fluoxetine in the muscle, liver and brain tissue of bluegill sunfish, channel catfish and black crappie living in Pecan Creek. The creek connects a Denton, Texas, water treatment plant to Lake Lewisville, the source of drinking water for Denton, Dallas and other nearby communities. For much of the year, the plant's daily 12 million to 13 million gallons of wastewater make up the creek's entire flow, creating an excellent "worst-case" scenario, Brooks says.
Treated municipal drinking water is considered safe, Brooks says, and the concentrations of the chemical found in the fish are measured in nanograms (billionths of a gram) per gram of fish tissue.
Nevertheless, discovery of the trace amounts is cause for concern. First, the fluoxetine concentrations Brooks discovered in the wastewater are similar to those used in laboratory experiments conducted by University of Georgia researchers, whose findings suggest exposure to similar concentrations in water might delay maturity in mosquito fish and frogs, which could affect reproduction and survival. The second reason for concern is that fluoxetine's metabolite, or active form, is relatively fat-soluble, meaning it may slowly accumulate in fish tissue over time, Brooks says.
"An antidepressant is not normally supposed to accumulate in fish tissue. We have to ask questions to understand the relative risk," he says, including whether the substance concentrates up the food chain. "Humans are actually more similar to fish than one might expect on a molecular and biochemical level."
Brooks has a one-year, $93,902 grant from the Environmental Protection Agency to study toxicity of effluents from municipal and industrial water treatment plants. He also is collaborating with Kevin Chambliss, assistant professor of chemistry at Baylor, to determine whether bottom feeders and fish that eat higher in the water column are exposed equally. In addition, he has worked with the City of Denton to evaluate a half-acre wetlands built to cleanse the treatment plant's discharge.
He also is part of a team of Baylor researchers working on a one-year, $300,000 contract from Waco-based Advanced Concepts and Technologies International to study detection and removal of nuclear, chemical and biological agents from drinking water for the U.S. government.
Brooks says his many research projects keep five graduate students and three undergraduates busy in his lab. "What makes this a unique opportunity for students is that they are asking very novel questions about an emerging area of science."