Shipping with Dry Ice and UN3373: Dangerous Goods for Life Sciences
Two dangerous-goods classifications come up constantly in life-science shipping: **UN1845** for dry ice, and **UN3373** for a Category B biological substance. Both have specific packaging, marking and documentation requirements, and getting them wrong is one of the most common reasons a carrier refuses a shipment at the counter. This guide sets out what each requires and the mistakes to avoid.
Dry ice: UN1845
Dry ice is solid carbon dioxide, classified as a dangerous good (UN1845) because it sublimates into gas and can build pressure or displace oxygen. Shipping it requires:
- Packaging that vents. The package must allow carbon dioxide gas to escape, never a sealed container.
- Correct marking and labelling. The UN1845 marking, the Class 9 hazard label, and the net quantity of dry ice.
- Declared net quantity. The weight of dry ice is declared on the documentation, and air carriers apply limits per package.
Category B biological substances: UN3373
A Category B biological substance (UN3373) is infectious material not in a form that causes permanent disability or life-threatening disease in healthy people. Most clinical and diagnostic samples that are infectious fall here. Shipping it requires:
- Triple packaging. A primary watertight receptacle, a watertight secondary packaging with absorbent material, and a rigid outer packaging.
- The UN3373 mark and the proper shipping name, Biological substance, Category B.
- An itemised packing detail appropriate to the mode and carrier.
When you ship both at once
A frozen biological sample on dry ice is common, and it is two dangerous goods in one package: the UN3373 substance and the UN1845 dry ice. Both sets of requirements apply, the triple packaging for the substance and the venting and marking for the dry ice, and both must appear correctly on the documentation.
The mistakes that get shipments refused
- Sealing a dry-ice package so gas cannot vent.
- Missing or wrong net-quantity declaration for the dry ice.
- Inadequate triple packaging or absorbent for the biological substance.
- Missing or incorrect UN marks and labels.
- Documentation that does not match the package.
Frequently asked questions
Yes. Dry ice is solid carbon dioxide, classified as UN1845, a Class 9 dangerous good, because it sublimates into gas that can build pressure or displace oxygen. It must be shipped in packaging that vents the gas, with correct marking and the net quantity of dry ice declared.