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Scientific evidence is at the heart of atrazine debate
By Jennifer M. Latzke In the 1950s scientists from a small chemical company discovered a class of herbicides-called triazines-that effectively controlled a list of broadleaf weeds that had plagued farmers for years. In 1958, that company, which would later be known as Syngenta, registered atrazine. Today, more than 45 pre-mix products contain atrazine, and it is used in more than 60 countries around the world as a critical component in conservation tillage systems. The Environmental Protection Agency (EPA) estimates 76.4 million pounds of atrazine are applied each year. Of that, 86 percent is used on corn acres, 10 percent on sorghum, and 3 percent on sugarcane. Three-quarters of all field corn acreage in the United States, according to the EPA, is treated with atrazine. In fact, the EPA estimates without the use of atrazine, corn growers would incur a loss of about 9 bushels per acre, plus the cost of a replacement herbicide. This would amount to a loss of about $28 per acre, or $1.6 billion of lost revenue each year, nationwide. In 50 years of evaluation and scientific peer review, atrazine has consistently been found to be a safe chemical for use in no-till and conservation tillage farming practices. Activist concerns Despite the 50 years of research and economical importance of this product, however, the EPA announced in October of last year it will hold four new Science Advisory Panels to yet again review the safety of atrazine. This came after a July 2009 update from EPA that stated, "Through its review of this data, the Agency has confirmed that none of the systems have exceeded OPP's level of concern, a 90-day average of 37.5 parts per billion of atrazine and its degredates. Concentrations below this 90-day average are considered to be safe." Why would an agency that supported continued use of atrazine in summer of 2009 suddenly change its mind and ask for more research? According to Jere White, executive director of the Kansas Corn Growers Association and Kansas Grain Sorghum Producers Association, the answer lies in articles that appeared in the New York Times and the Huffington Post in August 2009. "EPA acknowledges their actions were driven by activist-seeded articles in the New York Times and Huffington Post," White said. The stories used data from the Atrazine Monitoring Program and EPA's own maximum contaminant level testing, which were provided by the Natural Resources Defense Council. White said these two different numbers confuse consumers. The AMP is an intensive study of 100 community water systems in the Midwest and is a cooperative effort of EPA and Syngenta. The AMP program takes a closer look at areas with higher atrazine usage, and the EPA set a guideline under it of 37.5 parts per billion atrazine plus three metabolites (breakdown products) over a 90-day period. The EPA's MCL for atrazine, though, is set at 3 parts per billion based on an annual average in public drinking water. "You can do anything with numbers," White said in a release. "There are spikes, but those spikes were taken into consideration by EPA when the 3 parts per billion annual drinking water level for atrazine was set. That's why it is an annual average, and not a daily or weekly number. But to then take data from an entirely different program, and suggest that the levels were above the EPA's MCL for atrazine is simply misleading." The NRDC contends in watersheds the presence of high one-time peak concentrations of atrazine is just as important as the average for a longer period. In the report, "How the EPA is Ignoring Atrazine Contamination in Surface and Drinking Water in the Central United States," the NRDC calls for the phase-out of atrazine. "The toxicity associated with atrazine has been documented extensively," the report stated. "The adverse reproductive effects of atrazine have been seen in amphibians, mammals and humans-even at low levels of exposure. Concentrations as low as 0.1 ppb have been shown to alter the development of sex characteristics in male frogs, resulting in male frogs with female sex characteristics, hermaphroditism and the presence of eggs in male frog testes." A critical chemical for conservation White explained atrazine is a critical chemical for no-till farmers because of its broad spectrum of control. "Atrazine is critical in conservation tillage systems because it provides excellent residual control," White said. "It does not become attached to surface residue, but makes it through the residue to the soil to provide pre-emergent control. Atrazine also provides post-emergence activity, helping to control emerged weeds." The conservation tillage angle is important in the debate because soil conservation reduces field runoff, White explained. He said corn producers in the last decade have reduced land usage by 37 percent and soil loss by 69 percent, while still producing a bushel of corn. "Many no-tillers would find it hard to continue and even expand their conservation tillage without the availability of atrazine," White said. "Beyond financial cost, the inability to adequately control weeds would lead to more tillage and soil erosion." The NRDC's report recommends farmers use winter cover crops; mechanical weed control; delayed fertilizer application; crop rotation; and intercropping, where alternating rows of different crops are planted in the same field. "While the NRDC reports that farmers do not need atrazine, they do not offer any alternative product recommendations," White said. "The NRDC also likes to promote the fact that European corn farmers do not use atrazine, while ignoring the fact that they do use a triazine herbicide that's almost identical to atrazine and has nearly the same safety profile, called terbuthylazine." White said farmers must have access to chemicals like atrazine that can be used in safe and efficient manners. "After 50 years, we know more about the safety of atrazine than about any other tool they have," he said. "The current activist-driven activity subscribes to a 'precautionary principle' that might sound reasonable but would, in fact, decimate agriculture while ignoring the responsibility the world has to feed its people in the future." The next steps There are those who would argue reliance on a 50-year-old chemical is faulty. White acknowledged the hunt for an atrazine replacement continues in the labs of Syngenta and every other crop protection company in the world. "Many have even advertised that they had one," White said. "So far, that just hasn't happened. Other chemistries like glyphosate, have become very popular. Today we use atrazine more often as an enhancer at smaller application rates rather than a stand alone chemistry." Use of atrazine has evolved in its 50 years, mostly because farmers have become more efficient in their operations. For example, a few changes in application practices in the field were implemented in 2006 to meet EPA requirements for re-registration, White said. In October the EPA announced it is launching a comprehensive new evaluation of atrazine to determine its effects on humans. Once completed, the agency will decide if revisions of its current risk assessment of the chemical are needed, or whether new restrictions are necessary. The evaluation will cover atrazine's potential cancer and non-cancer effects on humans, including recent studies on atrazine and its potential association with birth defects, low birth weight and premature births. EPA is seeking advice from the independent Scientific Advisory Panel established under the Federal Insecticide, Fungicide and Rodenticide Act. EPA will hold meetings on atrazine throughout 2010, and will offer several public comment periods. White advised growers to let their voices be heard about atrazine by calling and writing their senators and congressmen. "When the EPA Special Review of the Triazine Herbicides was announced in November 1994, more than 80,000 comments were submitted supporting the continued safe use of atrazine," he said. "The Big First District of Kansas supplied more of those 80,000 than any other U.S. Congressional District." White also advised growers to contact the Kansas Corn Growers or Kansas Grain Sorghum Producers associations, or their individual state commodity associations, with comments and feedback. "If EPA sticks to the science farmers should have little problem with the outcome," he said. "On the other hand, NRDC wants to ban atrazine, regardless of the weight of scientific evidence to the contrary and farmers should never find that acceptable." The official position of the Kansas Corn Growers and the Kansas Grain Sorghum Producers is full support of a complete scientific assessment of atrazine, he added. "We are concerned about the current deviation in the EPA process but we will participate fully in that process," White said. Jennifer M. Latzke can be reached by phone at 620-227-1807, or by e-mail at jlatzke@hpj.com.
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