Publication 52 - Hazardous, Restricted, and Perishable Mail > Appendix C > USPS Packaging Instruction 6D
Regulated medical waste and sharps medical waste known or suspected to contain a Category A infectious substance is not mailable. Regulated medical waste and sharps medical waste as defined in 346.12f and 346.12g and containing materials classified as Category B infectious substances are permitted for mailing provided that all applicable requirements specified in 346.322 are met.
For packaging instructions for medical professional packages, refer to 346.322b–d.