Category B

The exception most work uses

On this page11

The wording Routine testing Unrelated to the diagnosis of infectious disease Low probability the sample is infectious All three, not any one What the exception does not remove So build to the triple packaging shape anyway Which is the same argument the veterinary property makes Document which route you took And train the person packing References

Three conditions, and all three have to hold.

The wording

Paragraph (b)(11) excepts human or animal samples transported for routine testing unrelated to the diagnosis of infectious disease, where there is a low probability the sample is infectious.

Routine testing

The ordinary panel: chemistry, haematology, drug levels, cholesterol. Work done to measure something rather than to find a pathogen.

Unrelated to the diagnosis of infectious disease

Which is the condition that does the most work. A sample taken because somebody might have an infection is related to that diagnosis by definition, whatever else is being measured on it.

Low probability the sample is infectious

An assessment, not a presumption. It is made about the sample and the reason it was taken, and it is the shipper's to make and defend.

All three, not any one

Routine, unrelated, and low probability. A sample that is routine but taken to investigate a possible infection does not qualify.

What the exception does not remove

The sample still has to arrive. Leakproof, absorbent, identifiable and intact are engineering requirements that outlive the regulatory question.

So build to the triple packaging shape anyway

Primary receptacle, something to contain a leak, absorbent, rigid outer. Not because the rule compels it, but because that is what stops a spilled sample becoming somebody else's problem.

Which is the same argument the veterinary property makes

A gap in a rule is not a gap in the hazard. The pet and veterinary property reaches the same conclusion about child resistant packaging from a different direction.

Document which route you took

If a shipment goes under the exception, the reasoning is worth writing down once for the category rather than being re-derived by whoever is packing that day.

And train the person packing

The classification is usually made correctly by somebody senior and applied incorrectly by somebody in a hurry. The packing bench is where this goes wrong.

References

49 CFR 173.134(a)(1)(ii) defines Category B as "an infectious substance that is not in a form generally capable of causing permanent disability or life-threatening or fatal disease in otherwise healthy humans or animals when exposure to it occurs", to be described as "Biological substance, Category B" and assigned identification number UN3373. Paragraph (b)(11) excepts human or animal samples transported for routine testing unrelated to the diagnosis of infectious disease where there is a low probability the sample is infectious. law.cornell.edu

49 CFR 173.199, Category B infectious substances. "A Category B infectious substance must be packaged in a triple packaging consisting of a primary receptacle, a secondary packaging, and a rigid outer packaging." Absorbent material "must be placed between the primary receptacle and secondary packaging" and "must be of sufficient quantity to absorb the entire contents of the primary receptacles". "The primary receptacle or the secondary packaging must be capable of withstanding without leakage an internal pressure producing a pressure differential of not less than 95 kPa." "The packaging must be capable of successfully passing the drop test in 178.609(d) of this subchapter at a drop height of at least 1.2 meters (3.9 feet)." "At least one surface of the outer packaging must have a minimum dimension of 100 mm by 100 mm (3.9 inches)." By aircraft, each primary receptacle may not exceed 1 L and each outer packaging 4 L for liquids, or 4 kg for solids. law.cornell.edu

Written from 49 CFR 173.199 and 173.134, and from the catalog as it stood on 19 October 2026. Nothing here is offered as a compliant primary receptacle for a regulated shipment: the pressure and drop requirements attach to a tested assembly, not to a bottle. Category A infectious substances are a different packaging instruction entirely and are not summarized. Sterility is not claimed for any product, and what a laboratory will accept is the laboratory's to say.