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National Agricultural Aviation Association eNewsletter
Voice of the Aerial Application Industry
March 18, 2021
In Case You Missed It!
NAAA Defends the Aerial Applications of Chlorpyrifos
Earlier this month, NAAA submitted comments to the EPA to argue against prohibiting aerial applications of chlorpyrifos. The comments were in response to the EPA’s proposed interim decision for chlorpyrifos. The EPA is required by the Federal Insecticide Fungicide and Rodenticide Act (FIFRA) to review the registrations for all crop protection products every 15 years. Interim decisions are being used by the EPA instead of a full reregistration of a product because the biological evaluations and pollinator protection assessments still need to be completed for most products.

The proposed interim decision indicated the proposed ban on the aerial applications of chlorpyrifos was based on risks to mixers and loaders, which was in turn affected by the use of a 10X safety factor. Elsewhere, however, the proposed interim decision stated the use of the 10X safety factor was for human health risks of concern related to the potential for neurodevelopmental effects on the young. The exposure path for these risks of concern was given as drinking water. NAAA commented that it is not appropriate to estimate risks to mixers and loaders based on a drinking water exposure concern. Additionally, NAAA pointed out that the worker protection standard (WPS) already prohibits anyone under 18 from mixing and loading pesticides, so human health concerns for the young should not impact risk assessments for mixing and loading chlorpyrifos.

While NAAA disagreed with how the risks to mixers and loaders were calculated, a mitigation plan was proposed to help ensure aerial applications remain labeled for chlorpyrifos. NAAA proposed requiring both a closed loading system and an elastomeric half facepiece cartridge respirator when mixing and loading chlorpyrifos for aerial applications. The EPA recommended this same combination on the recent proposed interim decision for triphenyltin hydroxide (TPTH), which NAAA referenced. NAAA also proposed banning the use of flaggers for aerial applications of chlorpyrifos, which, according to its industry surveys, is no longer used by the industry. To further work to ensure aerial application of chlorpyrifos continues, NAAA proposed banning the aerial application of all dry formulations of chlorpyrifos, including granule, water-soluble packets (WSP), and wettable powders. EPA models estimate a higher risk of inhalation for these formulations, which are rarely if ever used by aerial applicators.

NAAA’s comments highlighted the importance aerial application of chlorpyrifos plays for timely pest control, particularly when the ground is wet and when a pest outbreak requires a high number of acres to be treated in a short time. Many of the pests treated with chlorpyrifos, such as soybean aphids, are aggressive and can cause a great deal of crop damage in a short amount of time. NAAA pointed out to the EPA that it is these situations in particular where growers rely on aerial applications. NAAA referenced comments from the American Crystal Sugar Company that specifically stated the importance of aerial applications of chlorpyrifos for sugarbeet growers.

NAAA’s comments addressed and questioned, once again, EPA’s use of the Tier 1 model in AgDRIFT to estimate drift from aerial applications. This model uses many inaccurate assumptions and substantially overestimates the risk of drift associated with modern aerial applications. These faulty assumptions include a smaller than commonly used droplet size, a swath displacement shorter than industry standards, a slight inversion present during the application despite being prohibited on the label, wind speed measured at a height appropriate for ground applications instead of aerial applications and modeling the application to bare ground instead of a standing crop. NAAA referred the EPA to a letter submitted to the EPA’s Office of Pesticide Programs last June for a detailed analysis of all the inaccuracies of the Tier 1 model and how to use the Tier 3 AgDRIFT model to improve the accuracy of aerial drift estimates. NAAA argued in favor of a 15-mph wind speed limit, but indicated our acceptance of 10 mph if necessary to ensure aerial applications of chlorpyrifos. In terms of buffer zones, NAAA reminded the EPA again that all buffer zones need to be based on the wind direction, as spray drift only moves downwind, not upwind.

In addition to the threat to aerial applications, chlorpyrifos faces a complete ban in the U.S. Therefore, in addition to our own comments, NAAA helped author and signed onto a coalition letter to the EPA to support the reregistration of chlorpyrifos for all its currently registered uses. The coalition of 37 stakeholders included growers, retailers, applicators, distributors, manufacturers and crop consultants, including the Agricultural Retailers Association, American Farm Bureau Federation, American Soybean Association, American Sugarbeet Growers Association, National Alliance of Independent Crop Consultants, National Association of Wheat Growers, National Corn Growers Association, National Cotton Council, National Onion Association, National Potato Council, National Sorghum Producers, National Sunflower Association, and USA Rice.

The full comments submitted by NAAA to the EPA on the concerns with the proposed interim decision for chlorpyrifos can be read here. NAAA will be commenting on numerous registration review documents in 2021, including endangered species assessments for glyphosate and several important fungicides. NAAA remains committed to ensuring your operation has access to the products your customers demand to be applied aerially.

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This newsletter is intended for NAAA members only. NAAA requests that should any party desire to publish, distribute or quote any part of this newsletter that they first seek the permission of the Association. The views, thoughts, and opinions expressed herein do not necessarily represent those of the National Agricultural Aviation Association (NAAA), its Board of Directors, staff or membership. Items in this newsletter are not the result of paid advertising and are only meant to highlight newsworthy developments. No endorsement by NAAA is intended or implied.
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