WASHINGTON, Oct. 5, 2016 - An Environmental Protection Agency risk assessment that found atrazine widely distributed in waters throughout the Midwest could lead to a de facto ban on use of the herbicide, two major grower groups say.
The National Corn Growers Association and National Sorghum Producers are urging members to send comments to EPA by today, the deadline for providing feedback on the 520-page assessment, which was accidentally posted on the web by EPA in May before its official release in June. Corn growers apply most of the atrazine in the U.S. – about 60 million of the 70 million pounds used in the country in 2014.
Use of atrazine at or below label rates is likely to harm plant biodiversity and also cause reproductive problems in fish through runoff and spray drift, the ecological risk assessment says. It recommends that the current “community level of concern,” or CELOC, for atrazine be lowered from 10 parts per billion (ppb) to 3.4 ppb – a level NCGA and NSP say growers wouldn’t be able to meet.
“The proposed level cuts average field application rates down to 8 fluid ounces (approximately 1/4 pound) per acre,” NSP said in its action alert. “If EPA continues to use the same false logic or endpoints as noted in the preliminary assessment, atrazine would be rendered useless in controlling weeds on 90 percent of the acres in the U.S. – effectively eliminating the product.”
According to EPA’s risk assessment, the CELOC “is derived to ensure that the atrazine concentrations in watersheds do not cause detrimental changes in aquatic plant community structure and productivity.” Above 3.4 ppb, “ecologically significant changes in aquatic plant community structure, function, and/or productivity would be expected.”
But NCGA, which plans to submit official comments Oct. 5, says EPA is relying on studies its own Scientific Advisory Panel (SAP) said were flawed in 2012. EPA said in the assessment that it responded to the SAP’s comments in 2013 “and used the feedback in part to guide the amphibian and aquatic plant community portions of this risk assessment.”
In 2012, EPA said there was too much uncertainty in its analyses to attach a definitive number to the CELOC, putting it between 4 and 7 ppb. But the SAP recommended that EPA adopt a “weight of evidence” approach to amphibian studies, even those the agency had previously categorized as invalid.
The grower groups’ efforts to spur comment from supporters appear to have been successful. The number of comments submitted grew from just over 100 on Oct. 3 to more than 60,000 by the end of that day, according to EPA's docket. (The agency logs comments as received but won't post them online until it has reviewed them, or if they are “duplicate/near duplicate examples of a mass-mail campaign.”)
One letter came from three plant sciences professors at the University of Tennessee, who pointed to the emergence in that state of Palmer amaranth, which started becoming resistant to glyphosate in 2005.
“Up until 2005, glyphosate provided complete control of this weed,” said the professors, Robert M. Hayes, Angela McClure and Larry Steckel. “Unfortunately that is no longer the case, and as of today all counties in Tennessee have fields infested with this new Palmer biotype. Palmer amaranth is one of the most competitive weeds in the world and, left even partially controlled, can dramatically reduce yield.”
Palmer amaranth has been moving north; it was recently found in Minnesota.
Casey Kelleher, president of the Wisconsin Corn Growers Association, argued that “nearly 7,000 scientific studies” have been conducted on atrazine, and it’s been shown to be safe.
“For more than 50 years, atrazine has been incredibly important to corn, sorghum, and sugar cane farmers, enabling conservation tillage and no-till farming,” Kelleher said. “Atrazine helps farmers reduce aggregate soil erosion by up to 85 million tons per year. Banning atrazine would greatly hurt the conservation efforts of farmers by increasing both soil erosion and the use of fossil fuels.”
After it reviews the comments, “EPA may issue revised risk assessments, explain any changes to the draft risk assessments, respond to comments, and may request public input on risk mitigation before completing proposed registration review decisions” for atrazine, and two other so-called triazine herbicides, propazine, and simazine, the agency said in June when it released the risk assessment. About 3.8 million pounds of simazine were applied in 2014, according to USGS figures, and about 100,000 pounds of propazine.
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