JEFFERSON CITY, Mo. (DTN) -- Acephate, an insecticide commonly used by soybean and cotton farmers in the Midsouth to control stink bugs, will be a chemical tool removed from the proverbial toolbox under an EPA proposal now out for a 60-day public comment period.

Today, EPA released its proposed interim decision (PID) to cancel all but one use of acephate. The agency said the decision is based on its updated human health draft risk and drinking water assessments released in August 2023. The assessments showed significant dietary risks from drinking water for currently registered uses of acephate. EPA also identified worker, homeowner and ecological risks that would be mitigated by the proposed cancellations.

Acephate is an organophosphate (OP) pesticide first registered by EPA in 1973. It is registered for both agricultural uses, such as cotton and soybeans, and non-agricultural uses, such as tree injections for forestry and ant mound treatment around homes.

The pesticide interacts with the nervous system by inhibiting the acetylcholinesterase (AChE) enzyme. According to EPA, this process makes acephate effective against insects, but it can also occur in mammals, including humans, depending on the level of exposure. At high levels of OP exposures, AChE inhibition can lead to neurological effects such as tremors, fatigue and nausea. AChE inhibition is the most sensitive human health effect for evaluating exposures to acephate, the federal agency stated.

In an assessment of the use and pest management benefits of acephate for soybean production conducted by the EPA Biological & Economic Analysis Division, the agency reported the insecticide is used on soybeans almost exclusively in the Midsouth states of Arkansas, Louisiana, Mississippi and Texas. It is a minor component of insect pest management programs nationally, being applied to less than 2% of acres, but acephate is applied to 19% of soybeans within the Midsouth.

Often tank-mixed with bifenthrin, a pyrethroid, acephate is primarily used to control stink bug species that can cause significant damage to soybean flowers and seed pods. These include several green and brown stink bug species, especially the red-banded stink bug.

Though EPA's acephate PID proposes cancellation of most uses, it does maintain the insecticide's use for tree injection, stating that it does not contribute to drinking water exposure, there are no risks for workers, and, with label changes, would not pose risks to the environment. EPA said tree injections allow the pesticide to move throughout the tree to control pests. It is only allowed for use on trees that do not produce food for human consumption.

News of what is essentially a proposed agricultural ban on acephate was met with varying reactions.

"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 acephate is proceeding through its standard registration review process. The revised human health draft risk assessment, drinking water assessment and the PID are open for public comment for 60 days.

Commenters may propose alternative mitigation for the agency's consideration for some or all uses of the pesticide, and EPA will respond to these comments in its interim decision. If the agency determines alternative mitigation options that are voluntarily agreed to by the registrant can address the identified risks to satisfy the standard for continued registration of the pesticide, this could allow EPA to put protections in place faster than the statutorily required process for involuntary cancellation, which can take up to five years.

The last day to submit a comment is July 1, 2024.

To read EPA's proposed interim registration review decision, go here: https://www.regulations.gov/…

Links to EPA's human health draft risk assessment and drinking water assessment can be found here: https://www.epa.gov/…

To submit a public comment on the proposed interim decision, go here: https://www.regulations.gov/…

Jason Jenkins can be reached at jason.jenkins@dtn.com

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