Pesticides in US Rivers: Regional differences in use, occurrence, and environmental toxicity, 2013 to 2017

Sarah M Stackpoole; Megan E Shoda; Laura Medalie; Wesley W Stone

doi:10.1016/j.scitotenv.2021.147147

Pesticides in US Rivers: Regional differences in use, occurrence, and environmental toxicity, 2013 to 2017

Sci Total Environ. 2021 Sep 15:787:147147. doi: 10.1016/j.scitotenv.2021.147147. Epub 2021 Apr 17.

Authors

Sarah M Stackpoole¹, Megan E Shoda², Laura Medalie³, Wesley W Stone⁴

Affiliations

¹ U.S. Geological Survey, Water Mission Area, Denver, CO 80225, United States of America. Electronic address: sstackpoole@usgs.gov.
² U.S. Geological Survey, Ohio-Kentucky-Indiana Water Science Center, Indianapolis, IN 46278, United States of America. Electronic address: meshoda@usgs.gov.
³ U.S. Geological Survey, New England Water Science Center, Montpelier, VT 05602, United States of America. Electronic address: lmedalie@usgs.gov.
⁴ U.S. Geological Survey, Caribbean-Florida Water Science Center, Lutz, FL 33559, United States of America. Electronic address: wwstone@usgs.gov.

PMID: 33994194
DOI: 10.1016/j.scitotenv.2021.147147

Abstract

Pesticides pose a threat to the environment, but because of the substantial number of compounds, a comprehensive assessment of pesticides and an evaluation of the risk that they pose to human and aquatic life is challenging. In this study, improved analytical methods were used to quantify 221 pesticide concentrations in surface waters over the time period from 2013 to 2017. Samples were collected from 74 river sites in the conterminous US (CONUS). Potential toxicity was assessed by comparing surface water pesticide concentrations to standard concentrations that are considered to have adverse effects on human health or aquatic organisms. The majority of pesticide use is related to agriculture, and agricultural production varies across the CONUS. Therefore, our results were summarized by region (Northeast, South, Midwest, West and Pacific), with the expectation that crop production differences would drive variability in pesticide use, detection frequency, and benchmark exceedance patterns. Although agricultural pesticide use was at least 2.5 times higher in the Midwest (49 kg km^-2) than in any of the other four regions (Northeast, South, West, and Pacific, 3 to 21 kg km^-2) and the average number of pesticides detected in the Midwest was at least 1.5 higher (n = 25) than the other four regions (n = 8 to n = 16), the potential toxicity results were more evenly distributed. At least 50% of the sites within each of the 5 regions had at least 1 chronic benchmark exceedance. Imidacloprid posed the greatest potential threat to aquatic life with a total of 245 benchmark exceedances at 60 of the 74 sites. These results show that pesticides persist in the environment beyond the site of application and expected period of use. Continued monitoring and research are needed to improve our understanding of pesticide effects on aquatic and human life.

Keywords: Aquatic life benchmark; Detection frequency; Human health benchmark; Pesticide risk; Pesticide use; Surface water.