On January 26, the U.S. Environmental Protection Agency (EPA) announced reduced residue chemistry data requirements for many seed-treatment pesticide uses. The new guidance introduces important changes to EPA policy and creates a new tiered approach for applicants to use in determining field trial requirements for new seed-treatment uses.

In addition, the guidance confirms that proposed seed-treatment uses with residues equal to or below 5 parts-per-billion (ppb) in the aerial portion of a crop will continue to be classified as “nonfood.” Accordingly, these uses do not trigger tolerance requirements under the Federal Food, Drug and Cosmetic Act (FFDCA). The guidance also establishes maximum seed treatment application rates at or below which EPA will automatically consider a seed treatment use to be “nonfood” for particular crops.

Pesticide applicants should review the new guidance, summarized below, as part of their preparations to apply for any future seed-treatment applications for registration and related petitions for tolerance or exemption from tolerance.

A. Background

Consistent with the FFDCA, EPA establishes maximum residue levels, known as “tolerances,” before it will approve the registration of any food use for a pesticide. Historically, EPA classified a seed treatment use as “nonfood” if data from a radiotracer study demonstrated that there is no uptake of residues from treated seed into the aerial portion of the growing crop.

The new guidance stems from multiple field studies performed by EPA’s Health Effects Division’s (HED) Seed-Treatment Focus Group (STFG), in collaboration with Health Canada’s Pest Management Regulatory Agency (PMRA) and in response to multiple data requirement waiver requests received from seed-treatment product applicants over the years. The guidance significantly decreases the number of field trials and residue data requirements required to support certain seed-treatment uses.

B. New Guidance

The new guidance addresses seed-treatment uses in four key contexts:

1. Crops with Registered Foliar Uses

Data requirements are reduced in cases where the new seed-treatment use is proposed for a crop that already has existing foliar uses for the same active ingredient, as long as there are no additional metabolites of concern from the seed treatment application and certain other conditions are met. Under these circumstances, the existing tolerances established by EPA in support of the foliar crop uses will also be used to cover residues expected from the proposed seed-treatment uses. This relaxes EPA’s prior guidance, which required a case-by-case analysis of chemicals and crops together with a review by EPA’s Chemistry Science Advisory Council (ChemSAC) under these circumstances.

2. Crops Without Registered Foliar Uses

For crops that do not have any registered foliar uses, seed-treatment applications may be classified as nonfood uses if a radiotracer uptake study is conducted and demonstrates that the relevant residues of concern are less than 5 ppb for all relevant raw agricultural commodities (RAC). In such cases, no tolerances or additional data will be required. As noted above, EPA has also calculated application rates at which the maximum theoretical residue would equal 5 ppb, and all seed treatment uses at or below these estimated rates will automatically be considered nonfood uses.

If the radiotracer uptake study indicates that residues of concern equal or exceed 5 ppb in any of the RACs, the seed treatment use will be classified as a food use. Under these circumstances, a full set of field trial data must usually be generated for these RACs, and tolerances would be set based on the results of these studies.

However, if the radiotracer uptake study indicates that the residues of concern are only “slightly above” 5 ppb, the guidance permits a significant reduction in data requirements. Specifically, EPA provides applicants with the option to perform three field trials with an unlabeled active ingredient applied at a five-fold rate. Additional data and tolerance requirements will then be determined based on resulting levels of residues of concern for RACs in each trial.

3. Low Application Rates to Crops Without Registered Foliar Uses

The guidance also significantly reduces the data requirements for seed-treatment uses that have low application rates but no corresponding foliar uses or available radiotracer uptake studies. For human food crops under these circumstances, seed-treatment uses with an application rate equal to or less than 10 grams of active ingredient per 100 kilograms may forgo field trials altogether. Instead, a tolerance level will be set consistent with the limit of quantitation for relevant residues of concern. For RACs that are only livestock feed items, field trials may be reduced by 50 percent following three initial field trials.

4. Potato Seed-Piece Applications

The guidance establishes separate requirements for potato seed-pieces (PSPs), noting that PSPs are “unique” because they are much larger than most other crop seeds and, with significantly fewer seeds per pound than most other crops, require different seed-treatment applications. Accordingly, EPA outlines data requirements for scenarios in which there are no existing potato use registrations, as well as scenarios in which in-furrow or foliar potato uses have already been registered.