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EPA Releases Draft Risk Assessments for Mosquito Control Tool

For Release: September 8, 2020

Today, as part of the U.S. Environmental Protection Agency’s (EPA) efforts to protect public health and the environment, the agency is releasing draft human health and ecological risk assessments for naled – a critical tool for mosquito-borne disease control – for a 60-day public comment period.

Naled is registered for public health wide-area mosquito control, as well as insect control, at a variety of agricultural sites and food-processing facilities. It has been used safely and successfully to control mosquitos in the United States since 1959. More information about naled’s use to control mosquitos, including guidance for aerial spraying by mosquito control professionals in local governments and mosquito control districts can be found on EPA’s website.

The Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) requires EPA to periodically review pesticides to ensure that risk assessments reflect the best available science. The draft risk assessment is the first step in a multi-step process that is designed to both identify risk and then identify actions that can mitigate those risks.

EPA has identified both health and environmental risks associated with naled in the draft risk assessment. The draft assessment—which is intentionally conservative to ensure that it is protective of health and completed at the highest exposures—does show that estimated exposure from aerial application exceed EPA’s level of concern for children ages 1-2 years for up to four hours following spraying. EPA is actively working with mosquito control districts to encourage that they notify residents at least 24 hours prior to spraying so that residents can take protective actions. In addition, EPA has provided mosquito control professionals in local governments and mosquito control districts with advice on naled aerial spraying to reduce risks.

Both naled and the insecticide trichlorfon both degrade to form the insecticide DDVP. Draft human health risk assessments for trichlorfon and DDVP are also now available for public comment. After reviewing and considering public comments received and other information, EPA will issue proposed interim decisions (PIDs) proposing any potential risk management options for naled, DDVP and trichlorfon. The PIDs will also be available for public comment.

The draft risk assessments are available in each chemical’s registration review docket - EPA-HQ-OPP-2009-0209 (DDVP), EPA-HQ-OPP-2009-0053 (naled) and EPA-HQ-OPP-2009-0097 (trichlorfon) at The comment period expires in 60 days on November 9, 2020.


In September 2020, EPA plans to convene a FIFRA Scientific Advisory Panel (SAP) meeting to discuss new approach methodologies (NAM) that could have implications for organophosphate pesticides, including naled, DDVP and trichlorfon. These NAMs could reduce reliance on default uncertainty factors for human health risk assessment and reduce animal testing. Following the SAP meeting, if EPA determines that adjustments to the uncertainty factors for naled, DDVP, and/or trichlorfon are appropriate, the Agency will update the draft risk assessments.