The Department of Pesticide Regulation (DPR) has begun the formal review process of the pesticide imidacloprid and products containing it. The action, required under the Pesticide Contamination Prevention Act, comes after residue levels were detected above approved limits in 15 wells from 2014-2020.

In all of the incidents, use of the insecticide was determined to be for legal agricultural purposes. The wells with findings above the limit were in Fresno, Santa Barbara, and Tulare counties and the review process will determine whether imidacloprid poses a threat to groundwater or drinking water.

Imidacloprid is an insecticide used to control sucking insects, termites, some soil insects, and fleas on pets. It has been used in products sold in the United States since 1994, according to the National Pesticide Information Center.

DPR notified imidacloprid registrants that they can request a hearing to “determine if the legal use of imidacloprid has polluted or threatens to pollute California’s groundwater,” if they wish to maintain their registration. The deadline to request a hearing is Oct. 25 and DPR said it has begun receiving requests but did not disclose from which registrants. The hearing must be held within 180 days of that deadline, before a three-person subcommittee of the Pesticide Registration and Evaluation Committee.

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After the hearing, the subcommittee will provide a recommendation to DPR’s director, which could be one of three things, according to a DPR spokesperson: “continued agricultural use allowed without additional restriction, based on finding of no potential to pollute; continued agricultural use allowed with additional restrictions to address pollution potential; or, ag use of the pesticide is prohibited.”

The DPR director will then have 30 days to make a final decision.

Of the 253 pesticide products containing imidacloprid, DPR identified 125 whose agricultural uses make them subject to this inquiry, including 35 registered by Bayer, 12 by Nufarm and 10 by Loveland Products.

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