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What Is UN-3291? Understanding Regulated Medical Waste Classification

Last reviewed: August 17, 2026

If you ship or transport regulated medical waste, you will encounter the designation UN-3291 on labels, manifests, and shipping documents. UN-3291 is the United Nations number assigned to clinical waste or regulated medical waste that is unspecified. It is the standard classification used by the U.S. Department of Transportation (DOT) and international shipping regulations to identify medical waste during transport.

Understanding what UN-3291 means, how it affects your packaging and labeling requirements, and what your obligations are as a generator is essential for staying compliant with federal transportation rules.

What UN-3291 Covers

UN-3291 applies to waste that contains or is reasonably expected to contain pathogens, meaning infectious agents such as bacteria, viruses, parasites, or fungi that can cause disease in humans or animals. Under DOT regulations (49 CFR 173.134), this includes:

• Blood and blood products
• Items contaminated with blood or other potentially infectious materials
• Cultures and stocks of infectious agents from laboratory work
• Sharps waste (needles, scalpels, lancets)
• Pathological waste (tissues, organs, body parts)
• Isolation waste from patients with communicable diseases

UN-3291 is classified as a Division 6.2 material (infectious substance). However, it is placed in Category B, which applies to infectious substances that do not meet the criteria for Category A (which covers the most dangerous, known pathogens capable of causing severe disease).

Packaging Requirements

DOT regulations specify packaging standards for UN-3291 materials. The packaging must meet these requirements:

• Triple packaging system: The waste must be contained in a primary receptacle (the red bag or sharps container), surrounded by absorbent material if liquid is present, placed within a secondary packaging (a rigid outer container), and then placed in an outer shipping container.
• Leak-proof primary receptacle: Red bags must be sealed and leak-proof. Sharps containers must be rigid and puncture-resistant.
• Rigid outer container: The outermost container must be rigid enough to withstand the rigors of transport without crushing or puncturing. Corrugated fiberboard boxes, plastic tubs, and reusable hard-shell containers are common options.
• UN-rated packaging: For mail-back shipments, the outer packaging must be tested and certified to UN performance standards (drop test, stacking test) and marked accordingly.

For bulk transport by a licensed medical waste hauler, the vehicle itself may serve as the outer container, provided it meets DOT vehicle requirements for transporting infectious substances.

Labeling and Marking Requirements

Packages containing UN-3291 waste must be marked and labeled according to DOT rules:

• UN number marking: The outer container must be marked with "UN3291" (no hyphen in the regulatory marking).
• Proper shipping name: "Clinical waste, unspecified, n.o.s." or "Regulated medical waste, n.o.s." depending on the specific description used.
• Biohazard label: The universal biohazard symbol must appear on inner containers. The outer package must bear a Division 6.2 infectious substance label.
• Generator information: The name and address of the shipper (generator) must appear on the outer package.

Manifesting and Documentation

When UN-3291 waste is transported, proper documentation must accompany the shipment:

• Shipping papers: DOT requires a shipping paper (often combined with the waste manifest) that lists the UN number, proper shipping name, hazard class, and quantity of waste.
• Waste manifest: Most states require a medical waste tracking form or manifest that documents the generator, transporter, and treatment facility. This chain-of-custody document travels with the waste from pickup to final treatment.
• Emergency response information: Shipping papers must include emergency response contact information and procedures in case of a spill or accident during transport.

For mail-back sharps kits, the DOT allows certain exceptions for small quantities shipped via USPS, UPS, or FedEx, provided the packaging meets all applicable requirements and the carrier's specific rules for shipping infectious substances are followed.

Generator Responsibilities

As the generator of UN-3291 waste, your facility is responsible for:

• Proper classification: Determining that your waste meets the definition of regulated medical waste under both DOT and state regulations.
• Correct packaging: Ensuring waste is placed in compliant containers before it is handed to a transporter.
• Accurate documentation: Completing your portion of the manifest and retaining copies for your records.
• Selecting a licensed transporter: Verifying that your waste hauler holds the required federal and state permits for transporting Division 6.2 materials.

Most healthcare facilities rely on their waste management provider to supply compliant packaging and handle the documentation. However, the generator remains legally responsible for ensuring the waste is properly classified and packaged before pickup.

Why This Classification Matters

UN-3291 is more than a label on a box. It triggers a specific set of safety procedures that protect drivers, handlers, emergency responders, and the public from exposure to infectious materials during transport. Noncompliance with DOT packaging, labeling, or documentation requirements can result in fines, shipment refusals, and liability in the event of an exposure incident.

Working with a waste management provider that understands DOT requirements and handles documentation on your behalf is the most reliable way to ensure every shipment leaving your facility meets the standard.