Spray Drift and Volatilization: Issues to Navigate Carefully as EPA Develops Registration Review Decisions

Spray drift and volatilization issues increasingly are significant issues in pesticide product risk assessments. Earlier this year, the U.S. Environmental Protection Agency (EPA) issued drafts of key guidance documents, which focused on issues that were key in the chlorpyrifos petition response, and more recently, at least one registration review decision that reflects current and still evolving EPA policy on spray drift and volatilization issues.

How potential for spray drift and for volatilization are identified and then managed are likely to be key elements of ongoing and future risk assessments underlying forthcoming EPA registration and reregistration, with significant potential impact on these decisions. Registrants should monitor closely the policies, EPA decisions implementing them, and their potential impact on their products, particularly given the public interest in these issues.

The EPA documents issued in the past eight or so months are significant, particularly given the years of controversy and difficulty in past attempts to propose a clear and “simple” definition of “drift.” The perception by some advocacy groups is that EPA is not adequately addressing alleged harms posed by drift, and resulting appeals for court intervention will undoubtedly complicate the matrix of considerations influencing EPA’s policy. These reasons alone make monitoring the development of these policies critical for registrants.