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Risk\Benefit Analysis and Science Review
Timeline: Day 36-49
During this time period Risk\Benefit analysis is being completed and the Hazard group is completing its analysis, using findings from the Chemistry group. A final exposure assessment is being prepared. In PMN95-1601, the applicant submitted a request for a 2 week delay at this point, pleading a change in application procedure. The delay was granted and the change included in the review. The applicant can request a delay at any time. The agency cannot. The delay may be related to any need the company feels is important and may be in response to agency questions that engender need for additional data or analysis by the company.
Administrative and Science Information About The Delay
In general, during days 36-49 the biology and chemistry of the application are being intensively reviewed. The specifics of the hazard are being detailed and the exposure aspects are quantitated. In PMN95-1601 the request for a 2 week suspension created the need for additional information. In the case, however, no additional time was required. The review was completed in 90 days
Administrative Position on Requests For Suspension
After the application has been logged in, suspensions can only be requested by the applicant. EPA is committed to the 90 day schedule. A suspension can halt the 90 day countdown. In this example, in 95-1601 the reviewers felt that additional time was not needed. The request (for a change in application procedure) was made at a time when risks associated with application were being evaluated and no additional problems were anticipated.
Summary of Science Review of Application Modification
Modification
Initially, the submitter expected to dispense the soil/organism mixture using a cement mixer. As long as the mixture remained a wet slurry, we expected little potential for airborne releases of the GEM. The submitter has discovered that this method of application is not physically possible at the location and intends to inoculate the soil using hand-held sprayers.
EPA has been asked to evaluate this modification in terms of the potential for releases of the GEM to the environment
Discussion
In general, the potential source of releases to the environment from spray application is drift of the material away from the application area. Some limited information is available to quantify the potential loss for agricultural pesticides applications. For handgun application, the loss is reported to be 0.1%.
The lysimeter application is very different, however, because the application occurs within the lysimeter, a below-ground structure. The walls of the lysimeter provide a barrier against the air movements at the surface of the earth that can cause drift in the agricultural applications. Essentially, the air within the lysimeter is considered to be stagnant and any dispersion of the GEM aerosol is likely to be captured within the lysimeter. The difference in the driving force between the air movement and gravitational forces is likely to be many orders of magnitude. Rough calculations show that releases of the GEM from spray application within the lysimeter are likely to be less than 2,000 cfu/day over 1 day/year. See calculations attached.
III. Conclusions
As long as the spray application occurs at the soil surface and the surface is within the lysimeter, releases are expected to be quite low and comparable to the original assessment.
While this was being conducted, hazard and risk benefit analysis were ongoing. The change in application procedure did not affect either analysis.
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