SAN FRANCISCO (KCBS) – A new study on the long term impact of agricultural pesticides has found traces of so-called “legacy pollutants” including DDT in Western pond turtles, insects and soil sediment at Sequoia National Park.

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Brian Todd, an associate professor of wildlife, fish and conservation biology at UC Davis co-authored the study. Todd said controlling the flow of pesticides into national parks is pretty much impossible.

“Sequoia National Park is very interesting, because it begins in the foothills, just downwind of very heavy agricultural land in the southern part of the Central Valley,” Todd told KCBS. “It tends to accumulate from drift and runoff, a lot of the pesticides that have been used over the last several decades.”

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Todd says the study focused heavily on turtles because they are what’s known as an “indicator species,” whose reaction to changes in the environment serves as a kind of barometer of those changes.

Previous studies have shown pesticide exposure leads to neurological damage in the turtles.

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The findings were published in the online journal Chemosphere.