Illinois River Otters Being Exposed to Industrial Chemicals Banned Decades Ago

Otters living in rivers in Central Illinois are being exposed to high concentrations of chemicals such polychlorinated biphenyls (PCBs) and pesticides, despite the compounds being banned decades ago, according to new research published in the journal Ecotoxicology and Environmental Safety.

Samantha Carpenter, a wildlife technical assistant, and wildlife veterinary epidemiologist Nohra Mateus-Pinilla, both of whom are with the Illinois Natural History Survey, teamed up with Jan Novakofski, an animal sciences professor at University of Illinois to assess the cause of death in 23 river otters found dead between 2009 and 2011.

Their analysis centered around the liver concentrations of 20 chemical compounds once used in agriculture and industry, all but one of which were later banned.

Much to their surprise, dieldrin -- a byproduct of the pesticide aldrin, which was commonly used across the Midwest before it was banned in 1987 -- was present in higher concentrations in the recently deceased river otters than it was in eight specimens examined the years directly following the chemical's ban.

Levels of PCBs, which were banned after after being shown to cause cancer in humans and serious health threats in other animals, were similar, as were concentrations of DDE, which was used as a pesticide.

"The PCBs, dieldrin and DDE were the contaminants that we detected in highest concentration, in terms of average concentrations," Carpenter said. "And male river otters had significantly higher concentrations of PCBs compared to females."

Carpenter said that some studies of dieldrin linked it the development of cancer, Parkinson's disease or Alzheimers.

"But perhaps most concerning is that both dieldrin and PCBs can act as developmental neurotoxicants, meaning that developing fetuses can be harmed at concentrations much smaller than those that can impact the health of adults," she said.

Despite their ban nearly three decades ago, traces of the harmful chemicals are still regularly found in rivers where their use was historic.

A recent study on birds living along a certain region of the Hudson River in New York found that chemicals like PCBs -- which are residual in the water and soil after decades of unregulated dumping -- affect the bird's song.