The Direct Hazard of Atrazine
Posted By Lin on September 5, 2009
Atrazine is a widely used herbicide that is banned by the European Union due to its persistent groundwater contamination1 but is widely used in the United States, to the tune of 77 million pounds in 2003 alone. It is used to stop pre- and post-emergent broadleaf weeds.
How does this affect me, you might ask? Because atrazine is so widely used, it penetrates groundwater and enters underground aquifers. It also contaminates runoff into lakes and streams. Since most communities and cities use one of these sources to provide drinking water, this will eventually lead to serious problems.
The Natural Resource Defense Council has published a recent report2 entitled “Poisoning the Well” that includes a map of known regional atrazine concentrations, but the NRDC report does not take into account the potential impact of aquifiers. Most people assume “well water” is a local phenomenon, but in fact water may travel hundreds of miles underground. In the Twin Cities of Minnesota, for instance, local communities all draw their water from part of the Cambrian-Ordovician aquifier3,4, which stretches from Michigan to Indiana to Missouri to northeastern Minnesota. In many cases, metropolitan wells pull water from dozens if not hundreds of miles away. This means that the water you drink in Edina MN may be coming from farmland in southern Minnesota.
The Environmental Protection Agency claims that atrazine poses no threat to humans, in spite of the fact that, as a study by the Soil / Water / Air Protection Enterprise (SWAPE)5 states, atrazine has been shown to cause serious adverse health effects in humans including but not limited to cancer of the prostate, breasts, ovaries and and stomach, tumors, and non-Hodgkins lymphoma. Research suggests that atrazine primarily targets the reproductive system and developing organisms.
Part of the reason that the EPA claims that there is no problem is because they measure atrazine only once every 90 days. The half-life of atrazine in the soil is 13-261 days1, depending on soil composition and other factors. This means that much of the chemical can break down before the EPA measures it, particularly since it is not applied every day, but at intervals. As an example, the NRDC discovered that Little Pigeon Creek in Indiana2, the annual average atrazine concentration was 18.56 ppb, but the maximum concentration was 237.5 ppb! At a mere 1 ppb, atrazine begins negatively impacting plant life. One study by researchers at Purdue University, published in the journal Environmental Health Perspectives, suggests concentrations as small as 0.1 parts per billion may be associated with low birth weights.6
Furthermore, the breakdown chemicals would not be specifically register as atrazine in EPA tests. This does not mean that the impact from atrazine simply vanishes. Instead, atrazine breaks down via one of two processes, both of which result in the production of cyanuric acid1,7, one of the key chemicals that appeared during the 2007 pet food scandal and the 2008 Chinese milk scandal that affected children in China8. When cyanuric acid binds with melamine it can potentially cause kidney failure and death. According to the Minnesota Pollution Control Agency9, total residues of atrazine plus its metabolites may exceed atrazine regulatory limits even though atrazine does not.
Another point to consider is that the EPA secretly negotiated2 with the manufacturer of atrazine – Syngenta – to only monitor 40 watersheds out of over 1,000 at-risk watersheds, meaning that their coverage is spotty at best. Out of these 40, all showed detectable levels of atrazine.
The US Geologic Survey office recently added an online tool10 to see current atrazine concentrations in streams.
1. http://en.wikipedia.org/wiki/Atrazine
2. http://www.nrdc.org/health/atrazine/files/atrazine.pdf
3. http://pubs.usgs.gov/ha/ha730/pub/ch_a/Apg10.pdf
4. http://pubs.usgs.gov/ha/ha730/pub/ch_a/Apg11.pdf
5. http://ngwa.confex.com/ngwa/2009gws/webprogram/Paper5947.html
6. http://aquadoc.typepad.com/waterwired/2009/08/how-much-atrazine-is-safe-in-your-water-glass.html
7. http://umbbd.msi.umn.edu/atr/atr_map.html
8. http://en.wikipedia.org/wiki/Cyanuric_acid
9. http://www.cababstractsplus.org/abstracts/Abstract.aspx?AcNo=19912313464
10. http://www.usgs.gov/newsroom/article.asp?ID=2292
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