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EPA Addresses Human Health and Ecological Risks Posed by 13 Pyrethroids

For Release:  October 22, 2020

Today, EPA is releasing interim registration review decisions for 13 pyrethroid insecticides. As part of this action, additional label changes are required for some bifenthrin, cyfluthrin and beta-cyfluthrin and prallethrin products to reduce potential human health risks for residential post-application and occupational handler scenarios.

To address ecological risks, EPA determined that additional mitigation measures focused on reducing runoff and spray drift are necessary. These measures are as follows:

  • Increasing width for vegetative filter strips that serve as an organic filter to remove residues adhering to soil particles in runoff;
  • Decrease the width of the allowable spray for perimeter treatments to outdoor structures; and,
  • Adding new Spanish labeling and disposal statements.

Pyrethroids are synthetic versions of pyrethrins, which are a class of botanical insecticides derived from chrysanthemum flowers.

Pyrethroid and pyrethrin pesticides target a wide range of pests in agricultural and non-agricultural settings. Agricultural uses include grains, nuts, vegetables and other crops. Non-agricultural uses include pet health applications, termite treatments, and public health mosquito control.

The use of pyrethrins and pyrethroids has increased over the past decade as organophosphate pesticide use has declined. Under some circumstances, organophosphates are more acutely toxic to people, birds and mammals than the pyrethroids.

As required by the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), EPA periodically reviews existing registered pesticides to ensure they can be used without unreasonable risks to human health and the environment.

As part of that process, interim registration review decisions impose risk mitigation measures necessary to protect human health and the environment while EPA conducts additional assessments like an endangered species assessment.

The interim decisions being released today are for bifenthrin, cyfluthrin and beta-cyfluthrin, cyphenothrin, deltamethrin, d-phenothrin, esfenvalerate, fenpropathrin, imiprothrin, permethrin, prallethrin, tau-fluvalinate, tefluthrin and tetramethrin.

In addition to the IDs, EPA is also releasing the proposed interim decisions (PIDs) for gamma-cyhalothrin & lambda-cyhalothrin. Upon publication of Federal Register notice, public comments will be accepted for 60 days in the registration review dockets EPA-HQ-OPP-2010-0479 (gamma-cyhalothrin) and EPA-HQ-OPP-2010-0480 (lambda-cyhalothrin) at  

More information on the pyrethroids and pyrethrins proposed and interim decisions is available at EPA’s website