CHAMPAIGN -- Pollutants that have long been banned in Illinois are still showing up in river otters, according to a new study released this week by the University of Illinois.
The study says otters collected in recent years have had high concentrations of pesticides such as dieldrin and other chemicals including polychlorinated biphenyls, or PCBs.
Samantha Carpenter is a wildlife technical assistant at the Illinois Natural History Survey at the university's Prairie Research Institute. She called Illinois a one-time "hotbed" of the pesticide aldrin, the chemical from which dieldrin is derived.
For that reason, she told The News-Gazette in Champaign (http://bit.ly/18sGOQg ), "it's important to understand more about the exposure of fish-eating mammals, including humans, to dieldrin in Illinois."
Researchers focused on otters because they're at the top of the aquatic food chain and a good species to monitor to see what other aquatic life is being exposed to, said Nohra Mateus-Pinilla, a wildlife epidemiologist and the principal study investigator.
River otters were hunted and trapped almost to extinction in the state. Fewer than 100 were in Illinois in 1989, according to the Illinois Department of Natural Resources. A 1990s reintroduction program has pushed their numbers back up as high as 15,000.
Aldrin was once applied to crops, particularly corn, in large quantities across the Midwest. The United States banned its use in 1987 because of harmful effects on humans and wildlife.
Dieldrin affects brain development in human fetuses. It has also has been linked in some studies to cancer, Parkinson's and other illnesses, Carpenter said, though other studies haven't found those links to diseases.
PCBs were banned because of their effects in the 1970s.
Mateus-Pinilla isn't surprised to still find the chemicals in the environment.
"They are known as persistent pollutants," she said.
But the concentrations of dieldrin were higher than those found in the 1980s, when it was still in use.
Researchers say they now could look further into how the contaminants are building up in the otters, trying to determine their movements between watersheds to help figure out where they're getting the heaviest doses.