In 2008, EPA proposed revisions to its pesticide data requirements for antimicrobial pesticide products. The existing antimicrobial data requirements are in 40 CFR part 161. This action will revise the existing data requirements to reflect current regulatory and scientific standards. The data requirements will cover all scientific disciplines for antimicrobial pesticides, including product chemistry and residue chemistry, toxicology, and environmental fate and effects. In general, pesticide data requirements are codified in 40 CFR part 158, which describes the minimum data and information EPA typically requires to support an application for pesticide registration or amendment; support the maintenance of a pesticide registration by means of the data call-in process (e.g., as used in the registration review program); or establish or maintain a tolerance or exemption from the requirements of a tolerance for a pesticide chemical residue. This part also establishes procedures and other general requirements associated with the submission of data in support of a pesticide regulatory action. It does not, however, include study protocols, methodology, or standards for conducting or reporting test results; nor does this part describe how the Agency uses or evaluates the data and information in its risk assessment and risk management decisions, or the regulatory determinations that may be based upon the data. Once this regulatory change takes effect, data requirements for antimicrobial pesticides will be set forth in subpart W of 40 CFR part 158, and part 161 will be removed.