The Reregistration Eligibility Document (or RED) discusses the scientific data and other information supporting EPA's regulatory conclusion that products containing a pesticide do not pose unreasonable risks when used as directed by Agency-approved labeling, and are eligible for reregistration. The document presents the EPA's decision regarding the reregistration eligibility of the active ingredient propionic acid. The document consists of five sections. Section I is the introduction. Section II describes propionic acid, its uses and regulatory history. Section III discusses the human health and environmental assessment based on the data available to the EPA. Section IV discusses the reregistration eligibility decision for propionic acid and Section V discusses product reregistration requirements.