LB 16-175 - Widespread potential toxicity of select herbicides and insecticides on aquatic life in US Rivers, 2013-2017

Background/Question/Methods:

Pesticides pose a threat to environment, but because of the substantial number of pesticides in use, a comprehensive assessment can be challenging. In this study, advanced analytical methods and a national-scale monitoring network were used to quantify 221 pesticides in surface waters at 74 sites distributed across the conterminous US. Pesticide detection frequencies, estimates of agricultural pesticide use intensity, and potential risk were summarized across 5 regions (Northeast, Midwest, South, West, and Pacific). Potential risk was assessed by comparing measured surface water pesticide concentrations to human-health and aquatic-life benchmarks.

Results/Conclusions:

Pesticide use intensity and the mean number of contaminants detected per site was highest in the Midwest, while potential risk was distributed more evenly across regions. Human-health benchmark exceedances were rare, and while less than 10% of pesticides exceeded an aquatic life benchmark, 17 herbicides and insecticides were measured at levels that exceeded human-health or aquatic life criteria. These results show that pesticides persist in the environment beyond the site of application and expected period of use.