CFR›Title 42›Chapter I›Part 81›Subpart B ContainsSection 81.4CorpusDaily eCFRDisplayed edition2026-04-15Last updated2026-04-15 Subpart B—Definitions Sections 81.4 § 81.4 Definition of terms used in this part. Previous A Subpart A—Introduction Next C Subpart C—Data Required To Estimate Probability of Causation