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Pesticide Registration Withdrawn

Date Posted: April 26, 2000

The pesticide registration application for use of chlorfenapyr on cotton was recently withdrawn by the chemical’s manufacturer. Chlorfenapyr had been lauded as one of the most effective controls available for beet armyworm. The manufacturer’s decision to withdrawal their application came after the U.S. Environmental Protection Agency (EPA) had prepared and signed the required documentation to proceed with a formal denial of registration. The EPA’s decision was based on its determination that the risks of the chemical to the environment outweigh its benefits. In addition, the EPA determined that there are other effective chemicals available for control of beet armyworm that are less environmentally toxic. The withdrawal of the application for registration of chlorfenapyr use on cotton is considered an important success for the Fish and Wildlife Service whose Division of Environmental Contaminants had strongly opposed the pesticides registration (USFWS 1999).

Chlorfenapyr was the first member of a class of chemical compounds known as “pyrroles” to be proposed for pesticide registration. Pyrroles have a unique mode of action; they attack organisms at the cellular level by keeping mitochondria from fulfilling their energy producing role, resulting in cell death and, ultimately, death of the target organism. The EPA’s Environmental Fate and Effects Division determined that chlorfenapyr was one of the most reproductively toxic pesticides to birds they had ever evaluated. EPA documents specify that the high toxicity of chlorfenapyr to honeybees would likely result in adverse impacts to populations of pollinators. In addition, there is a potential for run-off from treatment sites to adversely affect aquatic organisms such as freshwater fish and invertebrates. Finally, chlorfenapyr appears to be persistent in the environment, thus increasing the likelihood of buildup in the environment and the potential for long term impacts to non-target organisms.

Several non-profit organizations, including the American Bird Conservancy, also played a pivotal role in the withdrawal of chlorfenapyr by responding to the EPA’s request for comment on the proposed registration and by providing scientifically accurate information to the public.

Mary Henry (703) 358-2148

U.S. Environmental Protection Agency, Office of Pesticide Programs. EPA Determines That Chlorfenapyr Does Not Meet the Requirements for Registration; American Cyanamid Withdraws Application

Scientific American. Pirate Fear: Controversy heats up about chlorfenapyr, a.k.a. Pirate--a pesticide some claim is the next DDT

U.S. Fish and Wildlife Service. April 30, 1999. Letter to the Office of Prevention, Pesticides and Toxic Substances, Environmental Protection Agency. (pdf file)

U.S. Fish and Wildlife Service, Environmental Contaminants Division. Pesticides

Last updated: June 12, 2015