On May 8, 2013, the US Environmental Protection Agency (EPA) Office of Pesticide Programs, Antimicrobial Division (AD), released its long-awaited final rule regarding data requirements for antimicrobial pesticides.1 The new requirements (Subpart W of 40 CFR Part 158 or Part 158W) update and replace Part 161 of Title 40 of the Code of Federal Regulations with the goal of “providing an up-to-date scientific framework for identifying and assessing the risks of antimicrobial pesticides sold or distributed in the United States.”2

This final rule represents a fundamental change in the way antimicrobial products will be reviewed in the US. The rule sets forth significant new data requirements for antimicrobial products, including food contact materials, antifoulant coatings and paints, and wood preservatives. The new requirements will likely result in significantly increased data costs for many types of antimicrobial products, and may increase the time required to complete the registration process.

The EPA codified 11 new data requirements in this final rule. One such major new requirement involves how AD will handle “down the drain uses” where the “EPA intends to conduct an assessment of the potential impact of the antimicrobial chemical on the microorganisms in the biological treatment processes of a [waste water treatment plant] and the potential for the antimicrobial chemical to pass through the [waste water treatment plant] in effluent.”3 Another major new requirement is the need to determine the nature and magnitude of antimicrobial pesticide residues on surfaces as a “more definitive trigger” for subsequent migration studies to determine rate and amount of materials being released from a product.

In the preamble to the rule, the EPA has reiterated its expansive interpretation of the its authority over food use products, indicating that the EPA will re-review and approve many of the same chemicals and uses reviewed by the US Food and Drug Administration (FDA). Thus food use products may be subject to extensive additional data requirements.

The EPA views the 158W rule as a “launching pad” for the use of “21st Century toxicology and integrated testing strategies” that may ultimately help reduce animal use and cost associated with toxicity testing. The basic strategy is to “maximize use of existing data from similar compounds, including information from new in silico and in vitro predictive models and exposure modeling to target in vivo toxicity testing that is needed to assess and manage risks,” including the use of quantitative structure-activity relationships (QSAR) and thresholds of toxicological concern (TTC).4 To evaluate the efficacy of this new approach to safety testing, the EPA will use “[d]ata from improved biomarkers of exposure and biological outcomes from population-based studies.”5

The rule is effective July 8, 2013. However, the EPA recognizes that registrants may not have all the newly-required data by that date, and therefore may “extend up to two years post-promulgation for situations in which a more time-intensive new study is missing.”6

There will be several additional guidance documents issued over the next several months as the EPA works to implement the new 158W data requirements. For example, the EPA intends to issue a “toxicity data requirement” guidance document on performing weight-of-evidence evaluation to determine overall toxicity data needs as well as evaluating waiver justifications. In addition, as mentioned in the final rule (78 FR at 26940), the EPA will prepare an Antimicrobial Use Site Index “to provide additional information about … use patterns.” Registrants will want to keep abreast of these Part 158W implementation actions over the next few months, as the forth-coming guidance will be critical to understanding the 158W requirements and risk assessment process.

In sum, the new Part 158 Subpart W represents a sea change in how antimicrobial products will be reviewed in the US. Companies seeking new registrations, amending existing registrations, or undergoing registration review for antimicrobial products will need to evaluate these data requirements to understand the potential implications for their products. In some case, consultation with the EPA may be necessary to fully understand the requirements applicable to a particular product.