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Pesticides/Residues

Dacthal (DCPA): EPA's first emergency pesticide suspension in nearly 40 years, and the tolerances it left on the books

Published November 9, 2026

Facts verified as of October 9, 2026

In August 2024, EPA did something it told the public it had not done in almost 40 years: it used emergency authority to pull a pesticide off the market before finishing the ordinary registration review process.

The agency's own description of the action: "for the first time in almost 40 years, EPA is using its emergency suspension authority to stop the use of a pesticide." The chemical was Dacthal. It had been registered and in active use on American vegetable fields for decades.

What just happened

On August 6, 2024, EPA issued an emergency order suspending every registration for DCPA, sold under the brand name Dacthal, an herbicide registered for use on crops including broccoli, Brussels sprouts, cabbage, cauliflower, and onions. EPA's own announcement framed the order as the first use of this specific emergency suspension authority in close to four decades. The agency's stated rationale centered on pregnant farmworkers and others near treated fields: EPA said DCPA exposure is linked to changes in fetal thyroid hormone levels, changes the agency associated with low birth weight, impaired brain development, lower IQ, and impaired motor skills later in life, some potentially irreversible.

On August 19, 2024, DCPA's registrant, AMVAC Chemical Corporation, told EPA it intended to voluntarily cancel its remaining U.S. products rather than contest the suspension. EPA announced the start of the cancellation process on August 28, with a Federal Register comment notice following August 29. EPA issued its final cancellation order on October 22, 2024, about two and a half months after the emergency suspension, ending every legal use of DCPA in the United States.

How we got here

DCPA had been registered in the United States for decades before the 2024 action; it is not a newly discovered chemical drawing fresh scrutiny, but an old one that EPA's periodic registration review had apparently not fully revisited until this cycle, part of why the agency reached for emergency authority rather than the standard multi-year review timeline. The 2024 action followed research EPA cited on fetal thyroid hormone disruption, an endocrine-pathway finding that, once an agency credits it as grounds for restricting a chemical, can move faster through emergency channels than a finding still working through an ordinary review queue.

EPA's emergency suspension authority under FIFRA exists for situations the agency judges to need faster action than the ordinary multi-year review process provides. The agency's own statement about using that authority for the first time in close to 40 years is a measure of how rarely that bar gets cleared, not a measure of how exceptional DCPA's underlying chemistry is relative to other registered pesticides.

Where regulators diverge

This looks, at first glance, like the pattern this newsletter usually flags in reverse: the U.S. moving fast while the EU holds back. It is not, quite. The European Union had already excluded chlorthal-dimethyl, the EU's name for the same chemical, from its list of approved substances fifteen years earlier: European Commission Decision 2009/715/EC, dated September 23, 2009, concerned the non-inclusion of chlorthal-dimethyl in Annex I to Council Directive 91/414/EEC and directed member states to withdraw remaining national authorizations for products containing it.

On the calendar, the EU got there first, the same pattern that shows up elsewhere in this newsletter. What is unusual here is not that the U.S. beat the EU to a decision; it did not. It is the mechanism the U.S. finally used: not the years-long registration-review queue most chemicals sit in, but an emergency authority EPA's own officials said the agency had not reached for in almost 40 years.

The U.S. remains the slower mover on this specific chemical by calendar time. It just moved, for once, by a faster and rarer mechanism than its usual one.

What the label actually says

Suspending every registration and canceling every product did not change the legal residue limits for DCPA in food. EPA's own FAQ on the chemical's status states plainly that "the product cancellation does not change the tolerances for DCPA."

Those tolerances, the maximum amount of DCPA residue legally permitted on treated crops under 40 CFR 180.185, remain in effect because FFDCA tolerance-setting and FIFRA registration cancellation are separate legal processes, and only the second one has been completed. EPA's FAQ states the agency will generally initiate the process to revoke DCPA's tolerances once every U.S. product is fully canceled and the tolerances are no longer needed to cover food imported from countries that still permit DCPA use, but gives no date for when that process will begin.

As of the FAQ's most recent update in December 2025, no Federal Register notice has proposed revoking DCPA's tolerances; a June 2025 Federal Register notice updating tolerances for eight other pesticides did not include DCPA among them. In practice, that means broccoli or onions grown domestically before the cancellation took effect, or imported from a country that still permits DCPA, can legally carry DCPA residue up to the existing tolerance, even though no American grower can currently buy or apply the chemical. On this point the EU's 2009 exclusion went further: it was a full non-approval, not a cancellation that left a residue tolerance standing.

Where PurityIQ fits

This is the kind of gap PurityIQ exists to put in front of you: not a verdict on whether that residue tolerance is the right number, but the two facts side by side, dated and sourced, that most coverage of the Dacthal suspension leaves out. The chemical's use is suspended. The legal tolerance for its residue in food is not.

You see the record. You decide.

Sources

Sources

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