Transporting biological materials between laboratories, hospitals, and research facilities requires strict safety protocols to prevent the accidental release of infectious agents. International regulations classify these substances based on their potential to cause disease upon exposure. This classification system ensures materials are packaged and handled appropriately according to the hazard level, with Category B representing a specific tier of moderate risk recognized globally.
Defining Category B Biological Substances
A Biological Substance, Category B, is defined as an infectious substance that does not meet the criteria for inclusion in Category A, the highest-risk group. While these materials contain pathogens capable of causing disease in humans or animals, exposure during transport is not generally expected to cause permanent disability, a life-threatening condition, or a fatal disease in otherwise healthy individuals. Category B substances are typically shipped for diagnostic or investigational purposes, such as clinical testing or research.
The distinction between Category B and the higher-risk Category A is defined by the severity of the illness caused by the contained pathogen. Category A materials, which include cultures of highly lethal agents like the Ebola or Marburg viruses, are known or highly likely to cause severe, irreversible, or fatal disease if they escape containment. Category B substances, in contrast, carry a lower public health risk, which allows for different, less stringent, but still highly regulated packaging requirements.
Regulatory Oversight and Identification
The classification of biological substances is governed by international transport organizations to ensure a unified standard across borders and modes of transport. Key entities, including the International Air Transport Association (IATA) and the US Department of Transportation (DOT), dictate the rules for shipping these materials. These regulations assign a unique identification code to Category B materials, which is universally recognized by shippers and regulatory agencies.
The identification code assigned to all Biological Substances, Category B, is UN 3373. This United Nations number signifies that the material is an infectious substance requiring specific handling and packaging outlined in international guidelines. The use of UN 3373 provides a standardized way for personnel globally to immediately understand the package’s nature and regulatory requirements. This code is intrinsically linked to Packing Instruction 650 (P650), which details the exact specifications for the required containment system.
Essential Packaging and Labeling Requirements
Compliance with Packing Instruction 650 requires the use of a mandatory “triple packaging” system to ensure containment even if one layer fails. The innermost component is the primary receptacle, which must be leakproof for liquids or siftproof for solids and directly holds the specimen. If multiple primary receptacles are used, they must be individually wrapped or separated to prevent contact and potential breakage during transit.
The second layer is the secondary packaging, which must also be durable and watertight or siftproof, fully enclosing the primary receptacle. For liquid specimens, this secondary layer must contain sufficient absorbent material, such as cotton wool or specialized pads, to absorb the entire volume of fluid should the primary receptacle leak. This absorbent layer is designed to contain the specimen and prevent contamination of the outer packaging.
The final component is the rigid outer packaging, such as a sturdy box or container, which protects the contents from physical damage during handling and transport. This outer packaging must have at least one surface dimension of 100 millimeters by 100 millimeters to accommodate the necessary regulatory markings. The exterior must be clearly marked with the proper shipping name, “Biological Substance, Category B,” and a specific diamond-shaped mark containing the UN 3373 code.
Common Materials Classified as Category B
The Category B classification applies to materials routinely transported for medical and research purposes when the presence of a high-consequence pathogen is not confirmed or highly suspected. Most patient specimens collected for routine diagnostic testing fall under this designation.
Examples of Category B materials include blood, urine, or tissue biopsies sent to a laboratory to check for common infections or monitor chronic conditions. This designation also covers swabs or fluid samples for common viral or bacterial testing, such as for influenza, COVID-19, or common bacterial cultures like Salmonella. Tissue samples preserved for pathology and human or animal excreta being tested for diagnostic purposes are also typically shipped under the UN 3373 designation.