U.S. scientists are trying to discover what impact the flushing of discarded medications and natural excretion of drug residue is having on aquatic life.

   University of Florida veterinary scientists, in collaboration with the Mote Marine Laboratory in Sarasota, Fla., are studying the bull shark's exposure to pharmaceutical drug residue found in the waters of the Caloosahatchee River  ear Fort Myers, Fla.

   "Because bull sharks have the unique ability to survive in both saltwater and freshwater environments, they are in close, frequent contact with people and, as a result, are frequently exposed to wastewater pollutants found in freshwater basins," said Jim Gelsleichter, senior scientist at Mote Marine Laboratory.

   The researchers are trying to determine whether exposure to prescription residue from water treatment plants affects the sharks' ability to grow and reproduce.

   "Treatment plants were designed to remove pathogens like viruses and bacterial agents, and that they do very well," said Nancy Szabo, co-investigator and director of University of Florida's Analytical Toxicology Core Laboratory. But, she added, such facilities aren't designed to deal with pharmaceuticals.

   The study is funded by the Charlotte Harbor National Estuary Program and a federal grant to the National Shark Research Foundation.

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