Bureau of Entomology and Pest Control
Fenthion is a pesticide registered by the United States Environmental Protection Agency (USEPA) to control adult mosquitoes. Fenthion is used for that purpose in Florida, and is applied by certified applicators who are routinely inspected by the Florida Department of Agriculture and Consumer Services to ensure the regulations regarding its proper use are followed.
The reports of bird deaths associated with the use of fenthion have not been verified by any Florida agency. The United States Fish and Wildlife Service (USFWS) has reported to the United States Environmental Protection Agency (USEPA) that bird deaths have been associated with fenthion use in Collier County, Florida, but has not agreed to share its information with any Florida agency responsible for pesticide regulation, wildlife protection, or natural resource management.
The USEPA, the only agency to which the alleged adverse effects have been reported, has completed its review of the available data and public comments received related to the preliminary and revised risk assessments for fenthion. Based on comments received during the public comment period and additional data received from the manufacturer of fenthion, the Agency revised its human health and environmental effects risk assessments and made them available to the public on October 21, 1999.
Based on its review, the USEPA believes additional risk reduction measures for fenthion may be needed. Options currently under consideration to address ecological risks include:
(1) requiring avian reproduction studies for the northern bobwhite and the mallard to refine the risk assessment;
(2) requiring additional acute toxicity studies for the mysid shrimp;
(3) restricting the use of fenthion to mosquito control districts in Florida that have developed a plan to identify critical/sensitive bird habitats and endangered species in their counties and have addressed ways to avoid exposure to those areas;
(4) changing the use rate on the label to allow the highest rate only for public health uses associated with confirmed mosquito-vectored diseases;
(5) requiring buffer zones to protect aquatic organisms, especially invertebrates; and
(6) requiring certain label changes to improve applications and lessen risk to non-target organisms.
Numerous opportunities for public comment have been offered as part of the decision-making process for fenthion, including announced public meetings held in Orlando on October 1999 and January 2001. In light of the reviews and workshops completed so far, the Florida Department of Agriculture and Consumer Services expects a final decision on additional data requirements and mitigation measures will be completed by the USEPA this year. The reregistration of fenthion for mosquito control in Florida is supported by the American Mosquito Control Association, the Florida Mosquito Control Association and the Florida Coordinating Council on Mosquito Control.
The Department has been working with the USEPA, mosquito control program experts and other stakeholders to identify the best ways to reduce risks associated with fenthion use. The agencies responsible for mosquito control are working to lessen potential impacts from the use of mosquito control chemicals. The Collier County Mosquito Control District in particular has been working to increase the efficiency of the methods used to apply fenthion and other pesticides so that less material is used, and there is less chance of non-target effects. These efforts are supported by research money appropriated by the Florida Legislature.
More information on mosquito control activities is available from the Department of Agriculture and Consumer Services by calling (850) 617-7995 or by visiting the following web site: Mosquito Control. Also, bird deaths can be reported directly to the Florida Fish and Wildlife Conservation Commission or by calling the Florida Fish and Wildlife Conservation Commission Regional Office in West Palm Beach at (561) 625-5122.
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