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EPA Posts Draft Revised Biological Opinion for Malathion, Chlorpyrifos, and Diazinon for Public Comment

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Today, the U.S. Environmental Protection Agency (EPA) is posting and seeking public comment on the National Marine Fisheries Service’s (NMFS) draft revised biological opinion (BiOp) for malathion, chlorpyrifos, and diazinon, three organophosphate insecticides commonly used to control foliage and soil insect pests.  

Under the Endangered Species Act (ESA), EPA has a responsibility to ensure that its actions, including many pesticide registration actions, do not jeopardize ESA listed species, or destroy or adversely modify their designated critical habitats. When EPA determines in its biological evaluation that a pesticide’s registration may affect these species or habitats, EPA must initiate consultation with NMFS, FWS, or both (the Services), as appropriate. In response, the Service(s) develop a BiOp that, among other things, determines whether the pesticide will jeopardize listed species or destroy or adversely modify critical habitat, and if so, describes measures to avoid these prohibitions. EPA is then responsible for implementing the BiOp.  

In 2017, EPA released its biological evaluations for malathion, chlorpyrifos, and diazinon, which found potential effects on listed species and their critical habitats. Later that year, NMFS issued a final BiOp for malathion, chlorpyrifos, and diazinon.  

In 2019, EPA requested to reinitiate formal consultation on these pesticide products to consider new information that was not available when NMFS issued its final BiOp. As part of the reinitiated consultation, EPA and NMFS provided opportunities for public and stakeholder engagement, including an opportunity for pesticide registrants to submit additional relevant information and inform EPA and NMFS of pending revisions to product labeling. EPA also supplied additional pesticide usage data to inform NMFS’s analysis.  

The draft revised BiOp released today is the result of EPA’s reinitiated consultation with NMFS. The BiOp contains NMFS’s preliminary findings that the use of use of malathion, chlorpyrifos, and diazinon, as specified in the approved product labels, is likely to jeopardize some listed species and adversely modify some critical habitats.  

In addition, the BiOp describes possible reasonable and prudent alternatives — actions that could prevent jeopardy to listed species or adverse modification of critical habitat. It also describes reasonable and prudent measures intended to minimize unintentional harm (i.e., “take”) to individuals of these listed species that could result from use of these pesticides. 

EPA and NMFS encourage public input on reasonable and prudent alternatives and reasonable and prudent measures. Specifically, NMFS is interested in comments regarding: 

(*) Additional risk reduction options beyond those described in the BiOp;

(*) The general feasibility of drift reduction measures based on wind direction;

(*) The consideration of measures based on geographic boundaries for wide-area adult mosquito control;

(*) The existence of stewardship programs that may be considered for risk reduction credit; and 

(*) Spray drift reduction technologies.  

Between December 2021 and February 2022, registrants of products containing malathion voluntarily committed to label changes to reduce potential effects to listed species and their critical habitats. While NMFS has listed the label changes in this draft revised BiOp, given the recent timing of these commitments, NMFS’s analysis of malathion’s effects in the BiOp does not reflect these label changes. EPA will continue to work with NMFS and malathion registrants to ensure NMFS has all pertinent information, which it may incorporate into its final revised BiOp for malathion, chlorpyrifos, and diazinon. EPA and NMFS also intend to meet with registrants of these chemicals to further discuss mitigation measures before finalizing the BiOp.  

In 2021, EPA announced a decision to revoke all tolerances for chlorpyrifos under the Federal Food, Drug, and Cosmetic Act to better protect human health, and chlorpyrifos tolerances expired on February 28, 2022. The draft revised BiOp is not related to this decision. This BiOp considers malathion, chlorpyrifos, and diazinon registrations as described in their labels under the Federal Insecticide, Fungicide, and Rodenticide Act. EPA is continuing to evaluate the non-food uses of chlorpyrifos as part of its ongoing registration review, which includes consultation with NMFS and the U.S. Fish and Wildlife Service (FWS). In the draft revised BiOp, the tolerance revocation was considered when determining whether species were likely to be exposed to chlorpyrifos. For uses that would be reduced or eliminated as a result of revoked tolerances, NMFS assumed reduced potential for species exposure to chlorpyrifos. In its final revised BiOp, NMFS may also consider changes to chlorpyrifos registrations resulting from EPA’s rule revoking tolerances, which could result in different effects on listed species than previously expected. 

After the public comment period, EPA will provide NMFS with the comments received and a summary of the comments for consideration before it finalizes the BiOp. Once NMFS issues its final BiOp, EPA will implement the BiOp taking into account any identified reasonable and prudent alternatives. Additionally, as part of implementing the BiOp, EPA will address any necessary actions related to reasonable and prudent measures included in the final BiOp. The final BiOp is the last step in EPA’s formal consultation process with NMFS.  

EPA is also in consultation on these pesticides with FWS, and has received FWS’s final BiOp for malathion. EPA plans to post this BiOp on its website in the next couple of weeks.  

Public comments on NMFS’s draft revised BiOp will be accepted for 60 days in docket EPA-HQ-OPP-2022-0172 at

See the Biological Opinion

SOURCE: US EPA Newsletter

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