Pesticide levels a “concern” for aquatic life, says study | Food and Environment Reporting Network

Worrisome pesticide levels in urban streams became far more prevalent in the past decade but declined slightly in agricultural streams, says a study by the U.S. Geological Survey of water samples from 1992-2011. Pesticide levels seldom exceeded human health benchmarks, said a USGS summary. Over 500 million pounds of pesticides are used annually in the United States and “some of these pesticides are occurring at concentrations that pose a concern for aquatic life,” it said.

In 90 percent of urban streams, researchers found one or more pesticide compounds that exceeded an aquatic-life benchmark in recent years. The figure was 61 percent for agricultural streams. USGS said the potential impact on aquatic life was likely to be understated because it had money to look for less than half of the more than 400 pesticides used in agriculture and the monitoring focused on pesticides dissolved in water.

The New York Times said, “The development of safer pesticides and legal restrictions on their use have sharply reduced the risk to humans from pesticide-tainted rivers and streams, while the potential risk to aquatic life in urban waters has risen, according to a two-decade survey published on Thursday.” The Times said the reduced risk to humans was a result of regulatory and marketing decisions that removed older and more dangerous chemicals from use.

The study, “Pesticides in U.S. Streams and Rivers: Occurrence and trends during 1992-2011,” was published in the journal Environmental Science and Technology and is available here, along with related USGS material.