Although previous malathion risk assessments indicated some risks of concern, the Agency refined the earlier assessments, revised risk estimates, and developed risk mitigation measures to address those earlier concerns.
For drinking water and residential bystander risks, application rates (pounds per acre or numbers of applications) were reduced. Occupational risks were mitigated through personal protective equipment or engineering control requirements on the labels and extending restricted-entry intervals (REIs) for some sites. Ecological risks were addressed by adding buffer zone and spray drift requirements to the labels and by lowering application rates for many uses.
Malathion is a member of the OP class of pesticides, which share a common mechanism of toxicity by affecting the nervous system via cholinesterase inhibition. A cumulative risk assessment, which evaluates exposures based on a common mechanism of toxicity, was conducted to evaluate the risk from registered uses of OP pesticides, including malathion. With mitigation measures for over 40 individual OP pesticides from risk management decisions completed during the past several years, the cumulative risks associated with OP pesticides do not exceed FQPA regulatory levels of concern. For additional information, see the OP Cumulative Risk Assessment (2006 Update) (http://www.epa.gov/pesticides/cumulative/) on the Agency's Web site and at http://www.regulations.gov in docket number EPA-HQ-OPP-2006-0618.
The Malathion RED is available in docket number EPA-HQ-OPP-2004-0348 at http://www.regulations.gov, and on the Agency's malathion reregistration Web page at http://www.epa.gov/oppsrrd1/op/malathion.htm. The Federal Register notice is available on our Web site at http://www.epa.gov/fedrgstr/EPA-PEST/2006/November/Day-29/p20150.htm .