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Illinois Discontinues Statewide Testing of Freshwater Fish for Organochlorine Pesticides

Press Release - Monday, September 18, 2023

Low levels of pesticides in state fish population demonstrate effectiveness of environmental regulations

SPRINGFIELD - The Illinois Department of Public Health (IDPH), in conjunction with the Illinois Environmental Protection Agency and the Illinois Department of Agriculture, has announced the discontinuation of statewide testing for organochlorine pesticides, such as DDT, in fish from Illinois lakes and rivers.

Organochlorine pesticides, including DDT and other similar chemicals, have been banned for decades, but the state had tested for them since 1974 because they are "environmentally persistent" and can build up in the tissue of fish and other animals. But the levels of these pesticides found through that testing has diminished to near zero over the past nearly 50 years, allowing the state to discontinue testing for those chemicals.

Testing for other contaminants in fish, including methylmercury and polychlorinated biphenyls (PCBs), will not be affected by these changes.

"The progress made in improving the safety of fish found in Illinois waterways is an incredible victory for public health and a testament to the success of sensible health and safety regulations," said IDPH Director Dr. Sameer Vohra. "Banning dangerous pesticides like DDT has made our water cleaner, our food safer, and our state healthier."

"The work done through the Illinois Fish Contaminant Monitoring Program not only provides important information to residents regarding fish consumption, but it also shows the significant progress being made to reduce pollutants in Illinois waters," said Illinois EPA Director John J. Kim. "Data clearly shows that these organochlorine pesticides are no longer prevalent in our waters or the fish that live in those waters, which is a testament to the achievements made through the Clean Water Act."

"This exemplifies the strength of our agriculture community," said Dr. Michael Woods, division manager of natural resources at the Department of Agriculture. "Illinois farmers are always seeking advancement in producing the highest yields using the best practices. To render any contaminant testing obsolete while Illinois farmers continue to produce at historic levels is a success story for the entire state."

Organochlorine pesticides like DDT were in widespread use across America dating back to the 1940s. Concerns about the impact of DDT on wildlife (particularly the bald eagle) and on people led to its ban for agricultural use in the U.S. in 1972; bans on other organochlorine pesticides followed in the 1980s. However, concerns remained about levels of the chemicals in the state's fish population.

In the early 1970s, the state implemented the Illinois Fish Contaminant Monitoring Program, a protocol of testing fish from the state's lakes, rivers, and streams. Lake Michigan is sampled annually, with samples drawn from rivers and large streams every five years, along with periodic testing of other public lakes. The testing measures whether fish samples contain pesticides, metals, or other dangerous chemicals at a level that would render them unsafe to eat.

In its early days, testing from state waterways indicated concerning levels of DDT, chlordane, and dieldrin in bottom feeding fish such as carp and catfish. Levels of chlordane were detected at rates making the fish unsafe to eat until the mid-1970s; DDT was found at unsafe levels until the early 1980s. Dieldrin, another organochlorine pesticide, was detected in levels deemed to be unsafe to eat as recently as the early 1990s. Since then, however, the pesticides are no longer found in unsafe amounts. With those chemicals no longer in use, continuation of the testing program for those pesticides is no longer necessary, saving both time and money.

Fish consumption advisories are issued annually by IDPH when certain chemicals are found in fish at levels that make it advisable to limit consumption of those fish. Advisories and associated resources can be found at the IDPH Fish Advisories website.

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