31
Mar
Hazardous Pesticide Breakdown Chemicals Found in Streams Nationwide, Raising Health Concerns
(Beyond Pesticides, March 31, 2021) Pesticide breakdown products are just as ubiquitous as their parent compounds in urban streams throughout the United States, 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.
USGS researchers subdivided the U.S. into five regions (Pacific NW, Coastal California, Midwest, Northeast, and Southeast) and took 76 to 100 water samples in small streams for each region over the course of five years. Samples were tested for 108 pesticide active ingredients, and 116 transformation products (also known as breakdown products or metabolites) that arise as active ingredients degrade after a pesticide application.
Of the active ingredients sampled, at least one pesticide was detected in 418 of 442 total stream samples conducted, representing a 95% detection rate. Breakdown products were just as widespread, with 396 out of 442 – 90% of streams sites showing detects. According to the study, 102 breakdown products were detected at least once, and nearly 30 were 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. Moreover, the scientists found that the primary source of metabolite pollution came from groundwater intrusion into streams, rather than surface runoff, indicating a long-term, chronic, and persistent source of toxicity for life that depends upon freshwater streams.
Herbicide metabolites were detected more frequently than insecticides and fungicides, but one problematic insecticide metabolite alone, fipronil sulfone (breakdown of the active ingredient fipronil), has the potential to significantly increase the toxicity of a steam to aquatic organisms. With fipronil sulfone detected in 20% of sampled streams – more frequently than its parent compound—there are significant implications for the health of U.S. waterways.
There is little data available on the toxicity of most of the breakdown products tested. While some are less toxic than their full active ingredient, some are also more toxic. Running a scenario where the breakdown products were equally as hazardous as the full active ingredient, researchers found risks nearly double those currently established for aquatic life in streams by EPA. The scientists take pains in their research to note that even their worst-case estimates may be too conservative due to lack of data and other issues. “We have new pesticides that are being introduced to the market every year, and each of those active ingredients has transformation products,” said study coauthor Barbara Mahler, PhD, to Chemical and Engineering News. “It’s a challenge to keep up.”
In addition to new pesticides, current use active ingredients and their breakdown products, are concerns related to synergy and mixtures. Another recent report from USGS, published in September 2020, likewise found 90% of U.S. rivers and streams to contain at least five or more different pesticides. Metabolites were not considered in the study, but represent another complexity not adequately accounted for by current regulations.
Next time you take a walk by a freshwater stream in your community, consider the range of products- pesticides, fertilizers, pharmaceuticals, cleaners, and the myriad of other household and industrial products that could make their way into that waterway. As Rachael Carson wrote in Silent Spring, “Water must be thought of in terms of the chains of life it supports…” The life in those streams is the basis for many urban ecosystems—where beavers and otters make their home, mosquito-eating dragonflies lay their eggs, and birds often find an easy meal. Consider that you also rely on that stream—possibly for your own drinking water, as many streams ultimately run into reservoirs, but also as a source of peaceful reprieve.
The concept of a Silent Spring is not one that exists outside our reality—it is an ever-present threat, and one that we continue to move towards with current practices. But it doesn’t have to be that way. Forgoing toxic pesticide use for cosmetic purposes on lawns and landscapes is one of the easiest ways to stop polluting local waterways. You can make change by eliminating pesticides on your own property, and working towards the passage of organic land care policies in your community. To get started, see Beyond Pesticides Tools for Change webpage, and reach out to [email protected] for additional assistance. By acting collectively, we can create a world where we don’t need to worry about the safety of the waterways we rely on.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Chemical and Engineering News, Environmental Science and Technology
