Hazardous Pesticide Breakdown Chemicals Found in Streams Nationwide, Raising Health Concerns

March 31, 2021 | Pesticide breakdown products are just as ubiquitous as their parent compounds in urban streams throughout the U.S., according to research conducted by the U.S. Geological Survey (USGS) and published in Environmental Science and Technology. The first of its kind findings place an important spotlight on the long-term impacts of pesticide use on health and the environment. As new analytical methods provide evidence of dangers that were until now unable to be recorded, the data point to the need for a wholescale rethinking of the way pesticide products are approved by the U.S. Environmental Protection Agency, and community-based measures to protect local waterways. Of the active ingredients sampled, at least one pesticide was detected in 418 of 442 total stream samples, representing a 95% detection rate. Breakdown products are just as widespread, with 396 out of 442— 90% of streams sites showing detects. According to the study, 102 breakdown products are detected at least once, and nearly 30 are detected in over 20% of samples. Researchers specifically point out the danger of detecting transformation products in small, headwater streams throughout the country. “The presence of pesticides and TPs [transformation products] in headwater streams is of particular interest because such streams comprise the majority of river network length and have a higher proportion of biodiversity than larger water bodies,” the study reads. [Mahler, Barbara et al. Inclusion of Pesticide Transformation Products Is Key to Estimating Pesticide Exposures and Effects in Small U.S. Streams. Environmental Science and Technology. 55(8):4740–4752, 2021.]