We understand how critical compliance is in biomedical transport. Every diagnostic sample carries valuable medical data and a responsibility to ensure safety, accuracy, and legality throughout its journey. The UN3373 standard governs the safe movement of Category B Biological Substances, and following it is not optional. It is a legal requirement designed to protect healthcare workers, couriers, laboratories, and the public.
It is important to note that UN3373 applies only to Category B substances, which are less hazardous than Category A pathogens but still require strict handling. Non-compliance carries significant risks. It can compromise diagnostic integrity, delay critical medical decisions, and in some cases lead to legal penalties or rejected consignments. By following best practices, we safeguard both people and results while keeping costs and turnaround times under control.
Understanding UN3373 Requirements
UN3373 packaging standards are set out under Packing Instruction P650, which is recognised across ADR (road transport) and IATA (air transport) regulations. These standards ensure that any package containing Category B Biological Substances remains secure and intact throughout transit.
Definition of Category B Biological Substances
Category B refers to infectious substances that do not meet the criteria for Category A pathogens but still pose a potential risk if leaked or mishandled. Typical examples include diagnostic specimens such as blood, urine, or swab samples intended for laboratory testing.
Core Compliance Elements under P650
To legally ship samples, the packaging must comply with several mandatory requirements:
Triple Packaging System:
- Primary receptacle such as a tube, vial, or vacutainer, sealed and leakproof.
- Secondary packaging that is also leakproof and contains sufficient absorbent material to protect against breakage.
- Rigid outer packaging that provides durability and impact resistance, with minimum surface dimensions of 100mm x 100mm.
- Labelling and Marking: Each package must be clearly marked with the UN3373 diamond symbol and the words “Biological Substance, Category B” in lettering at least 6mm high.
- Durability Testing: Packaging must withstand temperature changes, pressure variations, vibration, and an 80kg static load test to prove its resilience during routine courier or air transport.
By adhering to these requirements, we ensure that every sample sent for analysis maintains its integrity while meeting international transport regulations.
The Triple Packaging System
The foundation of UN3373 compliance lies in the triple packaging system. This approach provides three layers of protection that work together to keep biological samples secure during biomedical transport.
- Primary receptacle: The first layer is a sealed, leakproof container such as a vial, tube, or vacutainer. Each receptacle must be strong enough to hold the specimen without risk of cracking or leaking.
- Secondary packaging: This layer must also be leakproof and include sufficient absorbent material to contain the full volume of the sample in case the primary receptacle fails. We recommend 95kPa-tested pouches that can withstand air pressure changes during air freight.
- Rigid outer packaging: The final layer provides strength and impact resistance. It must measure at least 100mm x 100mm on one surface and carry the UN3373 diamond symbol and correct labelling. Our rigid outer boxes are designed to meet these requirements and are pre-printed for ease of compliance.
Best practice assembly tips
- Ensure primary receptacles are individually wrapped or separated to avoid contact.
- Use enough absorbent material to cover all samples.
- Double-check seals on both the secondary and outer packaging.
- Place labels clearly on the outer packaging and ensure they remain legible.
When assembled correctly, the triple packaging system meets legal standards and protects the diagnostic integrity of every sample.
Packaging Selection Criteria
Choosing the right packaging is essential for safe and efficient biomedical transport. While all solutions must meet UN3373 standards, several factors influence which type is best for your operation.
Key factors to consider:
- Compliance: Packaging must fully meet Packing Instruction P650 and carry correct UN3373 labelling.
- Size and volume: Choose packaging that matches the number and type of samples being shipped. Overpacking or underfilling creates risks.
- Durability: Select packaging tested for compression and drop resistance to handle courier or air freight conditions.
- Environmental resilience: Ensure materials can withstand fluctuations in temperature and humidity.
- Courier compatibility: Verify acceptance with postal and courier services such as Royal Mail or international air carriers.
Examples of compliant solutions
- Rigid outer boxes for strength and drop protection.
- Mailing envelopes with integrated absorbent layers for smaller consignments.
- Custom kits designed for specific workflows, combining leakproof pouches, absorbent pads, and pre-labelled boxes.
The right selection reduces costs, simplifies logistics, and provides confidence that your samples will arrive intact and compliant.
Handling and Transport Protocols
Even the best packaging must be supported by strict handling procedures, including but not limited to:
Pre-transport checklist
- Inspect primary receptacles and seals.
- Verify secondary packaging integrity and absorbent inclusion.
- Check outer packaging labels and documentation.
Courier and airline requirements
- Confirm the courier or airline accepts UN3373 consignments.
- Provide all required documentation, including airway bills where applicable.
Storage and stacking
- Avoid stacking packages beyond recommended weight limits.
- Store in temperature-controlled environments where necessary.
Chain of custody
- Maintain clear documentation at every handover point.
- Record tracking numbers and handling notes.
Emergency procedures
- Train staff in spill response.
- Use containment materials to isolate compromised packages.
- Report incidents in line with regulatory guidelines.
Protocols like these reduce risks, improve reliability, and ensure compliance at every stage of the journey.
Common Mistakes to Avoid
Despite clear regulations, errors in UN3373 compliance are common. Avoiding these mistakes is key to safe and efficient biomedical transport.
- Using non-compliant or untested packaging.
- Skipping absorbent material in the secondary layer.
- Applying incorrect or missing UN3373 labels.
- Overfilling containers or leaving them unsecured.
- Failing to train staff on correct handling procedures.
The Role of Trusted Suppliers
The choice of supplier plays a critical role in compliance. We provide packaging that is designed, tested, and certified to meet UN3373 standards, ensuring peace of mind.
Why this matters
- Certified suppliers guarantee compliance and quality.
- Pre-assembled kits reduce errors and save time.
- Custom solutions support operational efficiency and sustainability.
By working with a trusted partner, you reduce complexity and gain confidence that every sample is handled safely.
At Expert Medicals, we are committed to helping healthcare providers, laboratories, and diagnostic networks transport samples safely, securely, and in full compliance with international regulations.