Bayer CropScience has withdrawn its flubendiamide insecticide sold under the trade name Belt after losing its appeal against a decision of the US Environmental Protection Agency’s appeals board (EAB). Remaining product can be sold by retailers, however. The EAB decision upheld an earlier ruling by an administrative law judge who said Bayer and its fellow registrant Nichino America had agreed, upon conditional registration of the insecticide in 2008, that if the agency determined that flubendiamide caused “unreasonable adverse effects” on the (in this case aquatic) environment, they would voluntarily cancel their registrations.

Instead, the two companies filed an administrative challenge, which the judge said they did not have the right to do. By failing to request voluntary cancellation of their flubendiamide registrations within a week of EPA's determination that flubendiamide causes unreasonable adverse effects, Bayer and Nichino “failed to satisfy the termination condition in their flubendiamide registrations,” the EAB said.

In a statement, Bayer’s US arm said the Germany-based group “maintains the EPA's actions on flubendiamide are unlawful and inconsistent with sound regulatory risk assessment practices. The science supporting the registration of flubendiamide may be complex, but it is solid, and it's unfortunate that we were denied the opportunity to argue the scientific merits of our case.”

Bayer accused the environmental watchdog of refusing to engage in “meaningful dialog” and contended that EPA had shifted the goalposts “significantly” by deriving a toxicity endpoint for flubendiamide's degradate from a water study rather than a sediment study, which had found no observable adverse effects.

EPA “took a leap of faith” when it conditionally approved the registration for flubendiamide, the judge hearing the challenge said. “It could have simply denied the application based on then-existing data that suggested environmental risk.”