According to a five year study by the U.S. Geological Survey, pesticides and their derivatives, termed transformation products, are present in small streams and groundwater.  Findings from the survey were recently published in a peer-reviewed journal. *

Of specific concern is the insecticide fipronil and its degradation production fipronil sulfone found in 20 percent of streams in the set of 3,700 water samples from 442 locations across the U.S. A total of 108 pesticides and 116 transformation products were identified using liquid chromatography-tandem mass spectrometry. It will be remembered that fipronil was the subject of extensive disruption of the egg industries during 2017 in Belgium and Holland  following illegal and injudicious application of the compound to hens and their housing to control red mites.

Transformation products are formed from pesticides and herbicides by oxidation, reduction or hydrolysis.  In many cases transformation products can accumulate and in some cases are more toxic than the original pesticides.  This was a case with DDE the degradation product of DDT that was implicated in profound environmental effects involving wildlife and the subject of The Silent Spring by Rachel Carson.

Under the present Administration, the EPA will be more proactive both with respect to studies and publication and also the metabolic effects of pesticides in water.

The principal researcher for the study, Dr. Barbara J. Mahler, encourages research on the sublethal effects of both parent pesticides and their transformation products and long-term effects on reproduction, especially among aquatic organisms.

*Mahler, B.J. et al Inclusion of Pesticide Transformation Products is Key to Estimating Pesticide Exposures and Effect in Small U.S. Streams.  Environmental Science and Technology, March 10, 2021. DOI:10.1021/acs.est.0c06625