UF toxicologists are worried that pharmaceutical chemicals in the water system may be harming Florida's environment, according to a UF press release.
The federal rule for getting rid of old medicine is to simply put it down the drain.
Researchers at the Analytical Toxicology Core Laboratory, are studying bull sharks in the Caloosahatchee River in Fort Myers and the sharks' intake of leftover residue from old medicine in the water.
Their research is a joint operation with the Mote Marine Laboratory in Sarasota.
The Mote lab tags the sharks in the Caloosahatchee with implanted disks of silicone, which collect chemicals deposited by medicines into the water.
When the sharks are caught, the disks are retrieved and sent for analysis to the scientists at the UF Analytical Toxicology Core Lab.
At the lab, they try to determine which chemicals are present and what pharmaceuticals they come from.
The lab also receives blood and liver samples from the sharks to determine which chemicals actually make it into the sharks' bodies.
Nancy Szabo, director of the lab and co-leader of the investigation, said bull sharks are an excellent measuring tool for the study.
Szabo said because bull sharks are able to live in both freshwater and saltwater environments, they have a wide range of habitats, such as rivers and intercoastal areas.
This trait also puts them in close contact with people and the wastewater run-off that people produce.
Pharmaceutical chemicals also make it into the water system through human excrement.
"Typically, a drug contains much more of the active ingredient than the body will actually use," Szabo said.
Sometimes the body will only absorb 7 percent to 15 percent of a given medication, she added. The rest literally goes down the toilet.
Bull sharks are also top-level predators, meaning they are the end-of-the-line on the food chain for many other organisms.
This means that if a small fish absorbs a certain chemical and is eaten by a bull shark, the shark also consumes the chemical.
The effect is known as bioaccumulation, Szabo said.
Wastewater treatment plants have been relied on for decades to clean the water, Szabo said.
However, they were designed to remove bacteria and viruses, not pharmaceutical chemicals.
It is an established fact that pharmaceutical chemicals are present in much of the nation's aquatic ecosystems, Szabo said.
But their effect and potential danger has not been determined, Szabo said.
The bull shark study has only looked for chemicals related to certain drugs.
In the future, Szabo said, researchers hope to expand their analysis to other kinds of chemicals.
Szabo said one target could be popular drugs designed to lower cholesterol.
"Cholesterol-lowering drugs may directly impact the reproductive processes of wildlife species," Szabo said.
Many aquatic populations have seen a drop-off in reproduction, Szabo said.
The reason still remains a mystery, she added.
Although the issue of pharmaceutical contamination is a relatively new concern, Szabo said the Florida Department for Environmental Protection has already begun discussing possible solutions.
One example is finding a new way to dispose of medicine, Szabo said, adding that it is one of many ideas in a discussion stage.
"People are working as quickly as possible," Szabo said. "We just want to catch it early."
