Recently, the U.S. Environmental Protection Agency (EPA) issued a draft interim decision (PID) on acephate that calls for the cancellation of all but one application of the chemical. The agency noted that the proposal is based on a draft human health risk assessment, updated in August 2023, as well as a drinking water assessment, which revealed potentially significant dietary risks in drinking water from the currently registered uses of acephate.EPA also noted that risks to workers, homeowners, and the ecosystem will be effectively mitigated through the proposed ban.
Acephate, an organophosphate insecticide, has been widely used in agricultural applications, including cotton and soybean cultivation, as well as non-agricultural applications since it was registered with the EPA in 1973. Acephate interacts with the nervous system by inhibiting the enzyme acetylcholinesterase (AChE), a mechanism of action noted by EPA as conferring high lethality on insects. However, this effect is equally likely to affect mammals, including humans, and the magnitude of the effect depends on the individual’s level of exposure. According to the federal agency EPA, inhibition of AChE is the most sensitive indicator of health effects when assessing the effects of acephate exposure on human health.
EPA has evaluated the use and pest control benefits of acephate in soybean production, and the agency reports that the insecticide is used almost exclusively on soybeans in the south-central states of Arkansas, Louisiana, Mississippi, and Texas. Although acephate represents a relatively small percentage of insect pest management programmes nationwide, with less than 2% of the acreage applied, in the South Central region acephate use covers 19% of the soybean acreage.
Although EPA’s proposed Preliminary Interim Determination (PID) for acephate recommended eliminating most of its uses, the agency retained the use of the insecticide for tree injections.EPA stated that this practice does not increase the risk of exposure to drinking water, is not hazardous to workers, and does not pose a threat to the environment through the labeling change.EPA emphasized that tree injections allow insecticides to travel within the tree and effectively control pests, but limit its use to trees that do not produce fruit for human consumption.
Public reaction to news of the proposed agricultural ban on acephate has been mixed.
“I am troubled by what a ban on acephate could mean for my farm and our community,” said Luke Sayes, a farmer from Deville, Louisiana, and director for the American Soybean Association (ASA). “We currently have very few tools to manage destructive insect pests, like in this case, red-banded stink bugs, which can inflict significant yield loss if not managed.
“ASA and soy farmers are concerned with the way EPA has been assessing alleged dietary risks, such as with chlorpyrifos,” he said. “We plan to carefully examine the agency’s acephate claims to ensure they are supported by sound science.”
Nathan Donley, environmental health science director at the Center for Biological Diversity, had a different perspective on the EPA’s PID for the insecticide.
“Acephate rightly belongs in the dustbin of history, and we’re immensely grateful that the EPA’s Office of Pesticide Programs is moving to cancel this exceptionally dangerous pesticide,” he said. “Good riddance to acephate.”
EPA said that acephate is undergoing its standard registration review process. The revised draft Human Health Risk.
Assessment, Drinking Water Assessment, and PID are now open for public comment for 60 days, with a deadline of 1 July 2024 for comments. The public may submit suggestions for alternative mitigation measures for some or all of the uses of the pesticide, acephate, for EPA’s consideration.EPA will respond to these comments in its interim decision. If the agency determines that alternative mitigation measures voluntarily agreed to by the registrant address the identified risks and meet the criteria for continued registration of the insecticide, this may allow EPA to implement protections more quickly than the statutorily required involuntary cancellation process, which can take up to five years.
