Science

On the decline: pesticides in US waterways

In this June 8, 2009, photo provided by the US Geological Survey, USGS California Water Science Center research hydrologist Kelly Smalling collects water samples for pesticide analysis.

In this June 8, 2009, photo provided by the US Geological Survey, USGS California Water Science Center research hydrologist Kelly Smalling collects water samples for pesticide analysis.  (AP Photo/US Geological Survey)

Carbon dioxide levels may be spiking, but there's one environmental irritant that looks to be partially on the decline: pesticides in our nation's waterways. More stringent regulations and the creation of more Earth-friendly products get some of the credit for this backslide, reports the New York Times, citing a study conducted by the US Geological Survey from 1992 to 2011 and published in the journal Environmental Science & Technology.

Only one stream surpassed a pesticide benchmark for humans in the second decade of the study, down from 17% of agricultural streams from 1992 to 2001.

But while the risk to humans has subsided, aquatic life doesn't get off quite so easy, notes the Times. Up to 61% of agricultural streams and 46% of "mixed-land-use" streams still harbor pesticide levels that surpass acceptable levels for aquatic life; those numbers remained fairly stable over 20 years.

City waterways fared the worst over the study's term: Streams that exceeded the aquatic-life benchmark jumped from 53% in the first 10 years to 90% in the second 10; scientists place much of the blame on a roach and flea killer, as well as a common household insecticide.

Even worse news for aquatic creatures is that the study might not be showing how bad it really is, notes the Times: Because of financial restrictions or insufficient resources, researchers couldn't test for some other commonly used pesticides.

(Read about how a pesticide actually saved Darwin's finches.)

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