Transportation of Infectious Substances
Pipeline and Hazardous Materials Safety Administration · Feb 14, 1996 · Reference No. 96-0141
Interprets: 49 CFR § 173.134
Reggie’s quick take
A reader asked whether a culture sent to a lab for diagnosis counts as a "diagnostic specimen" and is therefore excepted from the Hazardous Materials Regulations. The agency said yes, as long as the material does not meet another hazard class definition (see § 173.134(b)(1)(ii)). The agency also said that once a culture is discarded and offered for transport or sent for treatment or disposal, it loses its diagnostic specimen status. It is then treated as an infectious substance, not regulated medical waste, and must be packaged and prepared under the infectious substance rules.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This is in response to your December 13, 1995 letter and conversation with a member of my staff concerning transportation requirements for cultures of infectious substances under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Your questions are paraphrased and answered as follows:
Q1. Is a culture that is transported to a laboratory for diagnosis considered a "diagnostic specimen" and, therefore, excepted from the HMR?
A1. The answer is yes. A material, including a culture, that is shipped for purposes of diagnosis is considered a "diagnostic specimen" and excepted from the HMR, provided the material does not meet any other hazard class definition. See 49 CFR 173.134(b)(1)(ii).
Q2. If the answer is yes, should the culture be handled as regulated medical waste or an infectious substance when transported for disposal?
A2. The culture loses its identity as a diagnostic specimen when it is discarded and offered for transportation or transported for treatment or disposal. In addition, a discarded culture that contains an infectious substance is not considered "regulated medical waste," as defined in § 173.134(a)(4). The discarded culture is considered an "infectious substance" and must be packaged and otherwise prepared for shipment in accordance with requirements applicable to infectious substances.
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.