New Approach for Assessing Insecticide Toxicity

A new grant to the Illinois Water Resources Center to fund researchers at Southern Illinois University could improve the accuracy and speed of monitoring programs used to gauge the health of waterways and set environmental regulations.

The three-year research project, led by SIU’s Michael Lydy, will use sediment samples collected by the U.S. Geological Survey during a larger contaminant study in the Northeast to test a new approach for measuring the toxicity of pyrethroid insecticides in urban streams.

“We are very pleased to continue our support of research with real significance for officials and communities in Illinois and throughout the country,” said Brian Miller, director of the Illinois Water Resources Center at the University of Illinois at Urbana-Champaign.

One of four projects selected this year by USGS in cooperation with the National Centers of Water Resources, the study will also examine the prevalence of pyrethroid resistance in a crustacean used by the U.S. Environmental Protection Agency and others to determine the overall toxicity of water and sediment. Resistance in Hyalella azteca—something already seen in California—would raise doubts about the accuracy of a spectrum of state and federal biomonitoring programs.

“The development of pyrethroid resistance in these populations could lead regulatory agencies to assume that water quality in contaminated streams is better than it actually is,” said Lydy, an environmental toxicologist who together with a researcher at Benedictine University at Springfield will lead a team of students to complete the study.

Just as important, he said, is the chain reaction chemical resistance could trigger. The longer Hyalella azteca live in pyrethroid-polluted waters, the more the chemical builds up in their tissue. Those high levels may be passed up the food chain when the crustacean is eaten by fish and birds.

To assess pyrethroid toxicity, Lydy and his partners will take advantage of a sampling method known as Tenax. The approach will allow them to hone in on the level of insecticide aquatic animals are actually exposed to instead of how much total chemical is in the waterway. This distinction is key for compounds like pyrethroids, which quickly bind to sediment and remain out of reach to some species.

Together with toxicity studies conducted with Hyalella azteca and other species commonly exposed to pyrethroids, the results will allow scientists and natural resource managers to more accurately predict the threat to aquatic life in roughly 48 hours—and at a fraction of the cost of more traditional monitoring methods.

Related work conducted in California by Lydy and others has already led to a cap on how much pyrethroid can flow into rivers and lakes while still meeting standards set by the Clean Water Act. These caps, known as total maximum daily loads, are used to control everything from mercury to E. coli.

The wide-reaching implications of the study make it a unique opportunity for the graduate and undergraduate students who will play a central role in the project.

Source: University of Illinois 

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