Atrazine: Still in Surface Waters and Still A Problem

Atrazine use distribution throughout the conterminous United States (USGS)

Sygenta, a Swiss-based multinational corporation, is really feeling the heat over their pesticide atrazine these days.  And for good reason, the scientific evidence of atrazine’s wide-spread health effects continues to mount and the Environmental Protection Agency is currently reviewing atrazine status under federal law.

So don't be surprised if you see Syngenta seize upon a technical report by the U.S. Geological Survey, which the agency published today in a release titled "Technical Announcement: Atrazine Not Likely to Exceed Drinking Water Standard in Agricultural Groundwater."  The actual title of the report, "Regression Models for Estimating Concentrations of Atrazine plus Deethylatrazine in Shallow Groundwater in Agricultural Areas of the United States," is considerably less flashy.

Before you get too reassured by these results, however, it’s best to keep a couple of things in mind:

  1. Atrazine contamination is a far bigger problem is surface waters (streams and lakes), where much of our drinking water comes from.  So the fact that it is relatively less prevalent in groundwater is no big surprise.  And, in fact, atrazine remains one of the most frequently detected pesticides in ground water.  You can even find the stuff in rain.
  2. As the release points out, the drinking water "standard" of 3.0 µg/L (3 parts per billion) that USGS uses isn't a standard at all.  USGS notes that "EPA’s Maximum Contaminant Level (MCL) of 3.0 µg/L for atrazine in public drinking-water supplies is not a regulatory standard for shallow groundwater or domestic supplies, but serves as a benchmark for potential human-health concerns."  As NRDC's report Poisoning the Well explained, EPA in fact provides few protections from consuming water with atrazine greatly in excess of these levels.  So long as the annual average concentration in a water system do not exceed 3.0 µg/L, the "maximum contaminant level" of atrazine allowed in drinking water has not been tripped.
  3. The USGS report still points to a high (greater than 10%) chance of groundwater contamination across large swathes of the United States.  As the report notes: "Results from this study indicate that the highest atrazine residue concentrations in groundwater underlying agricultural areas are likely to be in parts of the High Plains aquifer system, the Driftless Area of Illinois, Iowa, Wisconsin, and Minnesota and southeastern Pennsylvania."