05/03/2011 06:49 pm ET | Updated Jul 03, 2011

Follow the Evidence and Save the Frogs

Visit NRDCs Switchboard BlogLast week Jon Entine, a visiting fellow with the conservative American Enterprise Institute, attacked the link between the decline of frogs globally and pesticide use.  As Jon rightly notes, worldwide the biggest problem facing frogs today is the spread of the invasive “chytrid fungus,” which my colleague Josh Mogerman writes about here.  But I think Jon is way off base when he denies the connection between water pollutions--specifically pesticide pollution--and frog health.  Jon says:

Pesticides are concentrated in agricultural areas, which by and large are nowhere near sizable amphibian habitats.

The pesticides-are-dangerous theory rests on the credibility of the research of controversial University of California endocrinologist Tyrone Hayes. He's published numerous studies purporting to show that clawed frogs exposed to low doses of atrazine produce males with ambiguous genitalia and soprano-like croaks--hermaphrodites.

First, there is plenty of frog habitat in agricultural areas, particularly when it comes to pesticides like atrazine, which don’t stay put, running off of fields and into wetlands, rivers and streams.  In fact, according to government studies, atrazine is the most commonly identified pesticide in U.S. waters. And, if you live in the middle of the country like I do, it is everywhere.  Just check out this map:

2007 WARP Model Estimates of Maximum 21-Day Moving-Average Atrazine Concentrations in Streams

Second, say what you will about Dr. Hayes (my colleague Dr. Jennifer Sass has shared her thoughts here), but it is ludicrous to argue that the dangers of pesticide use to frogs (much less people) rests on one man’s research.  There have been numerous studies by other scientists about the impact of atrazine on amphibians broadly, and frogs in particular.  They include (this is a bit wonky, but stay with me):

  • Studies that link exposure to small amounts of atrazine for as little as two days to impaired development of the reproductive organs in male and female frogs;
  • Another study, which found that atrazine is a strong predictor of parasitic flatworm larvae in frogs, which can cause severe limb deformities and kidney damage to amphibians, including in declining populations of northern leopard frogs. The study also concluded that the combination of atrazine and phosphate--widely used in fertilizer for corn and sorghum production--significantly increased the presence of the flatworm; and
  • Other studies that show that atrazine disrupts hormone activity in amphibians, particularly those exposed during early stages of development, and has long-lasting effects, including increased susceptibility to infection, alterations in survival behavior,and elevated mortality rates.
Studies have also documented impacts on fish.  And we haven’t even talked about the new epidemiological work linking atrazine to health effects in people. I could go on, but you get the point. Jon closes by saying “Environmental challenges are complex. Data is more important than ideology.” I couldn’t agree more.

Tell the EPA to phase-out the use of atrazine in the Unites States.  Take action here.

This post originally appeared on NRDC's Switchboard blog.