(Refer to Standard 6A in Requirements for Medical Pathology Services)

The flowchart, together with Table 2.1, may help the user determine whether the specimen or substance is Category A, Category B, Exempt/Category C or some other category. The user must also take into account other types of hazard classes in addition to infectious and biological hazards.

2.1 Biological hazard classes

Patient specimens must be assigned to UN 2814, UN 2900 or UN 3373 as appropriate unless they are exempt (see below).

Category A

A Category A substance is an infectious substance that is transported in a form that, when exposure to it occurs, is capable of causing permanent disability, or a life-threatening or fatal disease in otherwise healthy humans or animals.

Infectious substances meeting these criteria that cause disease in humans or both in humans and animals must be assigned to UN 2814. Infectious substances that cause disease only in animals must be assigned to UN 2900. These are classified under IATA Hazard Class 6.2 and IATA Packing Instruction 602.

Assignment to Category A and the proper shipping name, ‘Infectious substances, affecting humans’ or ‘Infectious substances, affecting animals’, must be based on the known medical history and symptoms of the source human or animal, endemic local conditions, or professional judgment concerning individual circumstances of the source human or animal.

Indicative examples of substances that meet these criteria are given in Appendix 1.

Category B

A Category B substance is an infectious substance that does not meet the criteria for inclusion in Category A. Infectious substances in Category B must be assigned to UN 3373, and their proper shipping name is ‘Biological Substances, Category B’.

Human or animal material including but not limited to excreta, secreta, blood and its components, tissue and tissue fluids, and body parts, being transported for purposes such as research, diagnosis, investigational activities, disease treatment and prevention, are assigned to UN 3373. These are classified under IATA Hazard Class 6.2 and IATA Packing Instruction 650.

Exempt (for air transport) or Category C (for surface transport)

An Exempt/Category C substance is a patient specimen for which there is minimal likelihood that pathogens are present. It is not subject to the IATA Dangerous Goods Regulations if the specimen is transported in triple packaging that prevents leakage and is marked with the words ‘Exempt human specimens’ or ‘Exempt animal specimens’, as appropriate.

The following substances are not subject to the IATA Dangerous Goods Regulations (unless they meet the criteria for inclusion in another class):
  1. substances that do not contain infectious substances, or substances that are unlikely to cause disease in humans or animals
  2. substances containing micro-organisms that are non-pathogenic to humans or animals
  3. substances in a form where any present pathogens have been neutralised or inactivated such that they no longer pose a health risk
  4. environmental samples (including food and water samples) that are not considered to pose a significant risk of infection
  5. dried blood spots (collected by applying a drop onto absorbent material) or faecal occult blood screening tests, and blood or blood components that have been collected for the purposes of transfusion or for the preparation of blood products to be used for transfusion or transplantation, and any tissues or organs intended for use in transplantation.

Note: In determining whether a patient specimen has a minimal likelihood that pathogens are present, an element of professional judgment is required to determine if a substance is exempt under this paragraph. That judgment should be based on the known medical history, symptoms and individual circumstances of the source, human or animal, and endemic local conditions.

Examples of exempt or Category C specimens are:
  • tissue specimens fixed in formalin
  • fixed cytology smears
  • specimens of blood or urine to be tested for: antibodies, cholesterol, glucose, hormones, tumour markers, kidney or liver function, therapeutic drugs, non-therapeutic drugs and alcohol (the latter may have ‘chain of custody documents’).

2.2 Other hazards

Other hazards relevant to this document include:
  1. dry ice — covered by IATA Hazard Class 9, UN 1845 and IATA Packing Instruction 904
  2. flammable substances — covered by IATA Hazard Class 3
  3. corrosive substances — covered by IATA Hazard Class 8.

2.3 Hazard classification of common pathology substances


Table 2.1 summarises the hazard classification of the most common pathology substances.

Table 2.1 Hazard classifications of some pathology substances

Specimen or substance typeHazard classification
Any specimen with dry ice as a refrigerantClassification as per flowchart; additional IATA Hazard Class 9 and IATA Packing Instruction 904 apply to the dry ice
Blood culturesMost are Biological Substances, Category B, unless the organism is or suspected to be in Appendix 1, in which case they are Infectious Substances, Category A
Cell culturesExempt/Category C
Cervical sample, liquid basedWithout sample: IATA Hazard Class 3 flammable hazard
With sample: Included in packages containing Biological Substances, Category B, provided transported in small numbers
Fixed-tissue specimen on glass slideExempt/Category C
Microbial culturesMost are Biological Substances, Category B unless the organism is or suspected to be in Appendix 1, in which case they are Infectious Substances, Category A
Pap smears (glass slide type) — fixedExempt/Category C
Paraffin-embedded tissue specimenExempt/Category C
Patient specimenMost are Biological Substances, Category B or exempt Category C; use flowchart if in doubt
Suspected serious infectious respiratory illness
– Swab or nasopharyngeal aspirate
– Bronchial washing/aspirate/lavage
Category B, unless listed in Table A1.1
Category B, unless listed in Table A1.1