Last Friday NAAA submitted nine comments to the EPA for the agency’s re-registration review of pesticide active ingredients. The EPA is required by FIFRA to review the registrations for all crop protection products every 15 years to ensure dietary, water, environmental, occupational and endangered/threatened species safety. The active ingredients that NAAA commented on were for the following products: Boscalid, Fenpyroximate, Flonicamid, Mandipropamid, Metolachlor/S-Metolachlor, Myclobutanil, Propanil, Terbacil, and Triclopyr. The documents that EPA had submitted for comment were all risk assessments, conducted for each active ingredient to assess the risk to the environment and human health of the products being evaluated.

In all of the comments NAAA stated that the usage of the Tier 1 model in AgDRIFT for conducting the risk assessments is not an accurate representation of how modern aerial applications are conducted.  The faulty assumptions used in the model include a small droplet size, a non-dropped boom, a short swath offset, near-inversion conditions, and spraying over a bare surface. All of these assumptions result in a higher than realistic risk of drift assessment for aerial applications and are not the conditions that exist when aerial applications are made. NAAA provided more realistic assumptions and sources of data to back up those assumptions. While the risk assessments for three of the products did examine the impact of using a larger droplet size, they still had all of the other faulty assumptions.

For Boscalid, the ecological risk assessment stated that some of the labels with this active ingredient required a 100-foot buffer near water. NAAA commented that all buffer zones should only be required on the downwind side of the application and provided scientific evidence and currently approved labels to back up this argument. The comments also pointed out that if the EPA would use more realistic assumptions in AgDRIFT, the distance required for the buffer zone would be less than 100 feet.

The human health risk assessments for Myclobutanil found risks of concerns for flaggers and pilots when making applications of the dust formation. The EPA did not have direct exposure data for either pilots or flaggers for dust formulations, so they adjusted data for using a hand shaker can to apply dust. For the risk to flaggers, NAAA pointed out that 99 percent of aerial applicators use GPS for swath guidance, and that flagging is rarely used. In terms of the risk to pilots, NAAA commented that even when exposure estimates from a shaker can are adjusted, it is highly unlikely they accurately reflect the exposure to a pilot from inside a cockpit.

For Propanil, a herbicide used on rice, the ecological risk assessment found a risk of concern for chronic exposure to bees, both on the field and off the field. The risk assessment clearly states that bees are not attracted to rice, so NAAA questioned that there could be an on-field chronic exposure risk if bees were not likely to be in rice. For the off-field chronic exposure risk, a result of estimated drift, NAAA pointed out that the drift estimates were based on the inaccurate assumptions used in AgDRIFT.