The Pesticide Problem: Aquatic Life Imperiled

A new scientific study has revealed that humans are a lot better off, as pesticides are becoming both safer and increasingly restricted. However, the same work has found that pesticides in rivers and streams are a growing threat to aquatic life.

According to a study conducted by the US Geological Survey (USGS), and published in the journal Environmental Science and Technology, the worrisome level of pesticides affecting aquatic life in the United States has surged to 90 percent in just two decades.

This largely has to do with the fact that the number of streams and rivers containing pesticide contaminants has skyrocketed, with these supposedly "safer" products affecting about 50 percent more bodies of water from 2001 to 2011, when compared to the numbers in 1992 to the end of 2000.

In fact, the concentration of one or more type of pesticides in these streams is also far beyond benchmarks set by the Environmental Protection Agency (EPA).

Interestingly, it's not the widely used and potentially harmful farming pesticides that are pulling in the high numbers. Pesticides like neonicotinoids, which have been linked to the decline of pollinator populations across the country, are already being phased out of federal refuges, and even before then, were a strongly controlled (if still mishandled) product.

Wesley Stone, a USGS hydrologist and the study's lead author, told Reuters that the true problem is increased use of the insecticides fipronil and dichlorvos in urban settings - used to control pest populations that threaten buildings and transplanted trees.

The study found 30 urban waterways heavily contaminated by these two pesticides, exceeding the EPA benchmark by up to 90 percent. More worrisome still, byproducts of fipronil's natural decay - which are actually more toxic to marine life than the pesticide itself - were also detected at disturbing concentrations.

Karen Ryberg, who co-authored the study, told The New York Times that this is just the tip of the iceberg.

"We have pretty good data for agricultural uses, but they don't have the same for urban areas," she said. This is largely because it's very difficult to track store-bought and household products.

Ryberg added that it will take some time for assessments of urban pesticide use to catch up to the damage it's inflicting.

"There's a lag time between deciding a pesticide will be around for a while, then developing a lab test to detect it, and then having enough data to analyze it," she explained. "In science, that's a concern: How do you stay on top of it?"

The authors admit that they don't have an answer for that question.