IMDG Class 6.2 is the hazard subclass for infectious substances, substances known or reasonably expected to contain pathogens (microorganisms, viruses, prions, recombinant nucleic acids) capable of causing disease in humans or animals. The class is split into two categories with very different transport regimes: Category A for high-pathogenicity agents (UN 2814 for human/animal pathogens, UN 2900 for animal-only pathogens) and Category B for lower-pathogenicity material (UN 3373, “Biological substance, Category B”). Industrial chemical buyers rarely encounter Class 6.2, it is the routine cargo of pharmaceutical and biotech supply chains, diagnostic-sample shipping, and clinical trial logistics.
Category A vs Category B
| Category | Definition | UN number | Transport requirement |
|---|---|---|---|
| A | Pathogens capable of causing permanent disability or fatal disease in humans or animals | UN 2814 (affects humans / humans+animals); UN 2900 (affects animals only) | Triple packaging meeting P620; airworthy approved containers; IATA-aligned for air shipment |
| B | Other infectious substances not meeting Category A criteria | UN 3373 | Triple packaging meeting P650; less stringent than Category A |
Category A includes the small number of agents listed in the IMDG Indicative Examples (Ebola virus, Marburg virus, certain hantaviruses, cultured viral isolates of high-pathogenicity agents, prions). The list is short and specific. Most clinical samples, diagnostic specimens, and biotech research material fall in Category B.
Triple packaging requirement
Both categories require triple packaging, three nested containers each with a specific function:
- Primary receptacle (the innermost), leak-proof, contains the substance. Typically a screw-cap vial or sealed tube.
- Secondary packaging (middle), leak-proof, contains absorbent material to absorb the entire primary contents in case of breakage. Typically a sealed plastic bag or rigid container.
- Outer packaging, rigid outer box meeting drop-test and stack-test specifications. UN-marked.
For Category A (UN 2814, UN 2900), the packaging combination must be approved against UN Packaging Instruction P620 and tested at standardised drop and pressure conditions. The outer box typically carries a UN approval number (e.g. UN 4G/Class 6.2/2024/USA/…).
For Category B (UN 3373), the packaging meets less stringent P650 requirements. The outer box is marked with the white-and-purple UN 3373 diamond.
Common Class 6.2 cargo and its supply chain
| Cargo | Category | Typical origin to destination |
|---|---|---|
| Diagnostic blood / tissue samples | B (UN 3373) | Hospital to lab; lab to lab; reference material distribution |
| Clinical trial samples | B (UN 3373) | Trial site to central lab; lab to sponsor |
| Cultured viral isolates (low pathogenicity) | B (UN 3373) | Research lab to research lab |
| Cultured high-pathogenicity isolates | A (UN 2814) | BSL-3 / BSL-4 lab to lab; tightly restricted |
| Animal disease samples (humans not affected) | A (UN 2900) | Veterinary diagnostic; surveillance |
For a chemical buyer the routine encounter is incidental, a chemical importer occasionally also moves diagnostic kits, reagent samples, or test material that carries UN 3373 designation. Pure chemicals are not Class 6.2.
Segregation at sea
Class 6.2 must be stowed:
- “Separated from” Class 3 (flammable liquids), Class 6.1 (toxics), the toxic combination
- “Away from” Class 8 (corrosives), leakage of acids or bases onto biological samples damages the cargo
- “Segregated from” Class 7 (radioactives)
For Category A specifically, the cargo is rarely if ever moved by sea, air transport is the standard mode for time-critical biological samples. Class 6.2 by sea is mostly the diagnostic-sample and reference-material trade in non-urgent quantities.
Documentation chain
The Class 6.2 documentation has its own requirements:
- DG declaration with UN number, class, and category-specific information
- For Category A: a Dangerous Goods Note / Shipper’s Declaration for Dangerous Goods even for road or sea shipment
- Permits, many destination countries require import permits for Category A. The permit must be in place before the cargo dispatches.
- Material Transfer Agreements, for research material crossing institutional boundaries, an MTA is the contract documenting the transfer
- Biosafety officer sign-off at the consignor side for Category A and most Category B at university or research institutions
The destination permit step is the most common Class 6.2 failure mode. A research lab orders a culture from a Chinese supplier, the cargo dispatches, and arrives at the destination port without an import permit. The cargo is held while the permit is processed, which can take days or weeks. For perishable biological cargo this can mean cargo loss.
IMDG and IATA alignment
Class 6.2 transport rules are aligned across IMDG (sea), IATA (air), and ADR (road). The substance categorisation, packaging requirements, and labelling carry over almost identically. This reflects that biological samples often move multimodally, air for time-critical, road for connecting legs, and the alignment simplifies the supply chain.
The packaging certification is therefore commonly IATA-approved P620 / P650, which automatically meets IMDG requirements. Pure IMDG-only certified packaging exists but is the minority of the supply.
Operator note: the chemical-vs-bio crosshatch
A chemical buyer occasionally orders products from a Chinese supplier that turn out to be 6.2-classified, for example, a “bacterial fermentation extract” used as a chemistry reagent. The supplier ships under chemical classification; destination customs reclassifies as 6.2 on inspection because the product description references microbial origin. The reclassification triggers permit, packaging, and disposal requirements the buyer was not expecting. Always confirm whether the product is fermentation-derived and whether residual viable organisms are present. If yes, the cargo is potentially Class 6.2 regardless of how the supplier labelled it.
Related terms
IMDG umbrella code. UN number. Class 6.1 covers chemical toxics, distinct from biological infectivity. Segregation table.