Fewer Field Trials Needed to Register Seed-Treatment Uses

The Health Effects Division (HED) of EPA’s Office of Chemical Safety and Pollution Prevention has issued a memo that explains when the number of field trials to develop residue data for seed-treatment uses can be reduced.

The memo states that there are three circumstances under which fewer field trials will be required to support registration of seed-treatment uses. These circumstances and the residue data requirements are displayed in a decision tree included in the memo. A separate decision tree is provided for potato seed treatments; the memo indicates that there is only one situation in which residue chemistry data requirements for potato seed treatment can be reduced.

Retrospective analysis of data

The HED notes that it has received multiple waiver requests for seed-treatment field-studies residue data and has reviewed multiple field-trial data sets that indicated the potential to reduce the number of field trials required to support registration. To evaluate this hypothesis, the HED collaborated with the Health Canada Pest Management Regulatory Agency (PMRA) to perform retrospective analysis of all seed-treatment residue data submitted to the EPA/PMRA. The analysis resulted in a tiered approach for determining if current crop-specific field-trial data requirements are needed.

The outlined procedure differs from current HED guidance in that it provides direction concerning data requirements in cases where the seed-treatment use is being proposed for a crop that has existing foliar uses that have complete residue chemistry databases, and no additional field trials are needed; where field-residue trials are required to support the seed-treatment use to allow for a reduction in the number of trials for raw agricultural commodities (RACs) that are exclusively livestock feed items; and where a significant reduction in required residue data can be allowed in cases where the seed-treatment application rate is low.

Potato seed treatment

The memo also states that the only situation in which residue chemistry data can be reduced for potato seed treatment is in cases where a radiotracer study has been performed. In this case, potatoes are grown from seed pieces treated at a 1X application rate, and the residues of concern are less than 5 parts per billion in potato tubers. No further studies are required, and the use is considered nonfood.

Case study

The memo also describes the results of case study of the fungicide sedaxane conducted by HED’s Seed-Treatment Focus Group (STFG). The memo states that three separate petitions were received for sedaxane seed treatment on a variety of crops. If the seed-treatment decision tree were used for these petitions, a total of 109 field trials would have been waived, 40 field trials would have reduced data requirements, and five processing studies would have been waived. The STFG notes that depending on the use pattern, these types of savings may not apply to all chemicals; however, when chemicals do meet the criteria, both petitioners and the EPA would save a considerable amount of resources in terms of conducting, submitting, and reviewing the studies.

The memo is here.