On March 26, 2014, U.S. EPA released its draft "Human Health Bystander Screening Level Analysis: Volatilization Risks of Conventional Pesticides". This screening guide is intended to provide a mechanism for evaluating exposure risks as a result of the volatilization of conventional pesticide products. Earlier in the year, U.S. EPA released a similar draft guidance that proposed a mechanism to evaluate the potential risk of pesticide drift.
U.S. EPA's proposed screening guide for evaluating volatilization risks takes into consideration the chemical and physical properties of the pesticide to evaluate the rate at which a pesticide volatilizes from a treated site and then relies on the AERSCREEN model to calculate estimated pesticide concentrations in the air at different distances from the treated location.
In conjunction with the release of the draft screening guide, U.S. EPA also released the results of a screening analysis that U.S. EPA ran using this proposed methodology on 253 commonly used pesticides. Of these 253 pesticides, 68 pesticides failed. Per the draft guidance, if a pesticide fails the screening analysis, that is a trigger for U.S. EPA to further evaluate the volatilization risks of that particular pesticide. Commonly used pesticides that failed U.S. EPA's draft screening analysis included atrazine, chlorpyrifos, diazinon, and pyrethrin.
U.S. EPA's proposed screening analysis has already been the subject to criticism by industry groups that have gone on record as saying that the draft assessment is too strict, relies on inappropriate models. Environmental groups, on the other hand, believe the assessment to be too lax and incorrectly weights the effects of dispersion on the exposure assessment. The comment period on U.S. EPA's draft screening analysis guidance will expire on May 27, 2014