EPA Completes Bidrin Reassessment

EPA establishes mitigation measures for Bidrin.

April 5, 2002
Contact: Marjory Walker
(901) 274-9030

EPA has completed its reassessment of dicrotophos (Bidrin). While finding acceptable levels of risk for dietary and drinking water exposure, EPA is establishing risk mitigation measures based on its determination that exposure risks are high for applicators and the bird population.

NCC staff has worked closely with EPA and AmVac on the 18-month reassessment, developing a comprehensive benefits document in support of Bidrin’s continued use.

A restricted use organophosphate, Bidrin is registered only on cotton, mostly in the Southeast and Mid-South. Bidrin is very effective against resistant populations of plant bugs and stink bugs.

The risk mitigation measures, which take effect with the ’05 growing season, include a prohibition on aerial applications, handling of the product in a closed system to reduce worker dermal exposure, a 6-day re-entry interval (REI), establishment of a maximum per-acre usage rate and a cap on production of Bidrin at the average level of the past 3 years.

EPA believes that aerial prohibition will lower the concern for worker exposure, lessen spray drift concerns with water contamination and limit the treated area for bird exposure. Aerial applications will be allowed until the ’05 growing season.

Calculation of the re-entry interval of 6 days was based on usage rates of one-half pound of active ingredient per acre and an 8-hour workday. Crop advisors and scouts can enter a field during the REI if they are wearing early entry personal protective equipment specified on the label, or, if certified, under a Worker Protection Standard crop advisor exemption. Exceptions can be made for mechanical activities such as cultivating or spraying for weed control.

The seasonal maximum use was established at 0.83 pounds of active ingredient per acre, with only one-half pound of this use permitted prior to Aug. 1. Reducing the seasonal maximum will result in less overall exposure. Lowering the amount allowed prior to Aug. 1 will reduce the amount of exposure to birds during the breeding season. Although EPA believes the ecological risk is still high, the agency says the risk will be reduced by the overall reduction of use.

The benefits assessment conducted by EPA shows that while there are no alternative products for some pests, there are alternative compounds in a competitive price range for most of the pests controlled by dicrotophos. The production cap is required to ensure that use of dicrotophos is available for pest control, but that the use does not increase dramatically in the light of mitigation measures which may be required for other compounds.