Carbaryl Undergoing Reregistration Scrutiny
Under a legal agreement, EPA’s Office of Pesticide Programs must issue its Interim Reregistration Eligibility Decision for carbaryl by June 30, 2003. Carbaryl (N-methyl carbamate) is one of the most widely used insecticides in the United States. Thirty-nine million pounds of carbaryl are used yearly, with approximately 60 percent of the use in agriculture and the majority of the remainder in residential settings. Although the compound doesn’t persist in the environment for long periods, it is detected in surface waters, particularly in streams that drain urban watersheds.
The results from the dietary component of the risk assessment reveal values that are below levels of concern (LOC), and drinking water risk also appears to be below any LOC. There were concerns with regard to residential risks. With regard to residential handlers, eight of the 17 exposure scenarios modeled were over the target for combined dermal and respiratory exposure. Scenarios include garden and ornamental dusting, hose-end garden spraying, dog dusting, lawn belly-grinder, and hand-sprinkling granulars. It also has become clear that the current 12-hour restricted entry interval for carbaryl will most likely be modified to a longer period, such as two or three days. During a conference call regarding agricultural use, many use groups were asked about their flexibility for changing this period.
Also a concern is the environmental risks of carbaryl. Levels of concern were exceeded from all uses at the maximum label rates and for 89 percent of the uses at “average” use rates. Granular and bait formulations exceeded acute-risk LOCs for all 40 registered uses. All acute LOCs for freshwater and marine invertebrates were exceeded from carbaryl use at maximum and “average” application rates. The division responsible for the assessment has stated that perhaps the biggest mitigation option is the restriction of aerial application, since carbaryl is sufficiently volatile to result in aerial transport of the chemical. Longer reapplication periods would also reduce estimated environmental concentrations by 30 to 40 percent. (Pesticide & Toxic Chemical News, 4/7/03 & 4/14/03, EPA conference call of 5/7/03)
