If you’re transporting goods that could cause harm to humans or animals, you must follow the United Nations’ guidelines on transporting infectious substances. Failing to do so could cause significant danger to animal or human life, putting your reputation and bottom line at risk.

Diagnostic specimens assigned to UN3373 are ‘human or animal materials transported only for diagnosis or investigation. Such materials include excreta and blood as well as other tissues and fluids.’ Diagnostic specimens do not include live infected animals.

We’ve created this clear and straightforward guide to help you get your label and packaging compliance right when transporting infectious substances.

What is UN3373 Compliance?

The United Nations have split their guidelines relating to infectious substances (6.2 Toxic and Infectious Substances) into two distinct sub-categories: Category A and Category B.

What are Category A substances?

Category A is split into two further sub-categories: UN2814 (affecting humans) and UN2900 (affecting animals only) and is described as: ‘an infectious substance which is carried in a form that, when exposure to it occurs, is capable of causing permanent disability, life-threatening or fatal disease in otherwise healthy humans or animals.’

What are Category B substances?

Category B is known as UN3373 and is described as: ‘an infectious substance which does not meet the criteria for inclusion in Category A.’

When we talk about UN3373 compliance, we explicitly refer to the label and packaging compliance required to ship Category B substances.


Adherence to UN3373 compliance is overseen by the bodies responsible for the transportation of dangerous goods via road and air: The European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR), and The International Air Transport Association (IATA), which supports aviation with global standards for airline safety, security, efficiency, and sustainability. These bodies have separate, relevant guidelines to transport UN3373 infectious goods either by land or air.

What is P650 packaging?

If a substance has been classified as belonging to UN3373, then it must be packed for transport according to a set of guidelines known as Packing Instruction 650 (P650 or PI650). This is a list of requirements covering the quality and construction of the packaging used for transport. P650 is split into guidelines for ADR and IATA, with each having slightly different demands on packaging containing UN3373 infectious substances.

Most of the guidelines for road and air transport are the same; however, there are many differences. These are detailed below:

If you’re coming to sample transport for this first time, or you’re not 100% confident with the terms, phrases and words associated the sector, we have created this helpful jargon guide, which aims to simplify some of the sector jargon you may encounter on this page, or any of the pages we’ve linked in this resource.

Intelsius UN3373 Packaging and Resources

At Intelsius, we’ve designed and distributed high-quality UN3373 Category B sample transport packaging for over 20 years. We are experts in getting Category B, UN3373 Infectious Substances from A to B safely and effectively while meeting P650 standards.

Below you can see how our PathoPak sample transport packaging solution ticks all of the boxes regarding UN3373 substances, including how infectious substances are safely stored inside a rigid primary receptacle, which is then provided with further protection by leakproof secondary and rigid outer packaging.

UN3373 Category B Schematic

As well as the PathoPak range of UN3373 compliant sample transport packaging, below we have a detailed view of our PathoShield sample transport packaging, with leakproof primary and 95kPa secondary leakproof bag and rigid outer packaging. All of these products come with the appropriate UN3373 markings to ensure compliance throughout your cargo’s journey.


The pascal (Pa) and kilopascal (kPa) are the most common pressure units throughout the world. As outlined by UN3373 Category B IATA guidelines: ‘The primary receptacle or the secondary ageing shall be capable of withstanding, without leakage, an internal pressure of 95 kPa (0.95 bar) in the range of -40 °C to +55 °C (-40 °F to +130 °F).’ Our PathoShield, PathoPak, PathoSeal and PathoPouch sample transport solutions are designed to withstand these pressures, ensuring the safety of your payload in transport.

Label Compliance

Ensuring your samples have the correct labelling is vital for adhering to UN3373 Category B guidelines. Below you can see UN Class 6.2 markings that must be clearly displayed on the outer packaging of any UN3373 Category B shipment.

From left to right, the markings break down to mean:

The UN3373 Biological Substance Category B logo shown below must also appear on the outer packaging of your shipment when transporting Category B UN3373 infectious substances:

Intelsius design complete sample transport solutions with the correct UN labelling built into the service; however, if you’d like to enquire specifically about label compliance, we have created a helpful guide which you can find here.

To continue the conversation or inquire further about our UN3373 compliant packaging, get in touch with a member of your local Intelsius branch here.

All of the Intelsius UN3373 compliant solutions mentioned in this article are available to purchase online.