The second-most widely used weedkiller in the country, atrazine, poses potential chronic risk to birds, mammals and fish due to runoff and spray drift, said a draft ecological-risk assessment by the EPA. The assessment is part of a review that started in 2013 on whether to extend use of the broad-spectrum herbicide in the U.S. for 15 years.
First approved in 1958, atrazine is used on more than 60 million acres of cropland annually, including 70 percent of the corn crop, the largest single use. The herbicide is used on the bulk of sorghum, sugar cane and sweet corn plantings, too. The EPA review of atrazine, like a similar review of glyphosate, the No. 1 herbicide, is taking months longer than expected.
“EPA levels of concern are exceeded by as much as 22, 198 and 62 times for birds, mammals and fish respectively,” said the 520-page draft report. Even at low application rates — well below those commonly used — “terrestrial plant biodiversity and communities are likely to be impacted from off-field exposures via run-off and spray drift.”
The National Corn Growers Association said research over the past half-century found atrazine to be safe. “It is widely used because it is among the most reliable herbicides available and it plays a critical role in combating the spread of [herbicide-] resistant weeds,” said NCGA president Chip Bowling. The Swiss seed and chemical giant Syngenta, maker of atrazine, said the draft assessment set the “level of concern” for birds, plants, mammals and fish too low, which exaggerated the risk.
“Atrazine is … well known as a hormone disruptor that has been linked to birth defects and cancer in humans, and contamination of ground-, surface- and drinking-water supplies,” said the Center for Biological Diversity, a group focusing on protection of endangered species. “Atrazine needs to be banned now.” In April, the Environmental Working Group cited research by a UCLA biology professor that showed atrazine altered the reproductive systems in frogs.
“Mobile and persistent in the environment,” atrazine has the “propensity to move into surface and ground water,” said the EPA draft. “This is confirmed by the widespread detections of atrazine in surface water and ground water.”
Atrazine and related triazine herbicides “all exhibit neuroendocrine effects seen across mammals and can alter hormone levels in rates that may result in developmental and reproductive consequences. In addition to this primary effect in mammals, acute and chronic exposure of animals to [triazines] has shown significant reduction in body weight and organ weights across multiple animal and bird species.”
The EPA set a 60-day comment period on the draft, after which it will revise the risk assessment as it deems appropriate. The assessment is expected to go to the EPA’s Scientific Advisory Panel in 2017, the agency said.
The EPA homepage on atrazine is available here.