CFR›Title 21›Chapter I›Part 509›Subpart B ContainsSection 509.30CorpusDaily eCFRDisplayed edition2026-04-27Last updated2026-04-27 Subpart B—Tolerances for Unavoidable Poisonous or Deleterious Substances Sections 509.30 § 509.30 Temporary tolerances for polychlorinated biphenyls (PCB's). Previous A Subpart A—General Provisions