How To Classify Biological Substances For Shipment

Practical advice on classifying biological substances

This article will provide you with an overview of the different definitions and categories of biological substances, and how to determine the category, name and number for each. For next steps in packaging, marking/labeling and documentation requirements, see our companion article.

Shipping biological substances has lots of regulations and terminology. It's important to follow these rules, as the shipper is responsible for the package and can face delays, fines, or liability if they are not followed. Once you review some basics, the process is straightforward. 

Dangerous goods and infectious substances

First, let’s take a look at some common terms and broad definitions you are bound to encounter. The first are dangerous goods, a very broad category which includes dry ice, batteries, metals, paints and some biological substances. According to the International Air Transport Association, dangerous goods are “articles or substances which are capable of posing a risk to health, safety, property or to the environment and which are shown in the list of dangerous goods in these regulations or which are classified according to these regulations.” 

According to the IATA, infectious substances are “Substances which are known or reasonably expected to contain pathogens. Pathogens are defined as micro-organisms (including bacteria, viruses, parasites, fungi) and other agents such as prions, which can cause disease in humans or animals.” 

Before shipping, you must identify which of the following categories your substance falls under:

  • Category A Infectious Substance
  • Category B Biological Substance
  • Genetically Modified Organism/Microorganism
  • Exempt Human /Animal Specimen

How to classify biological substances

Need Shipping Assistance? 

Mercury provides a comprehensive domestic and international shipping solution for biological substances. Contact us today.

Upcoming Webinar

International and Domestic Shipping for Life Sciences

March 7, 2024 | 2PM

Learn about clinical shipping and Research Use Only classification. Common issues in life sciences shipping and best practices to overcome them. Expert guidance on pre-clearance and clearance for seamless shipments across borders.


Category A Infectious Substances

Some shipped substances are classified as either Category A infectious substances or Category B biological substances. The difference is the risk posed to humans or animals if the substance leaks. Certain higher risk substances are defined as Category A (UN2814 for humans and UN 2900 for animals). Category A is defined as: “An infectious substance which is transported in a form that, when exposure occurs, is capable of causing permanent disability, life-threatening or fatal disease in otherwise healthy humans or animals.” This includes cultures, or intentionally propagated pathogens include lab stock cultures or presumptive positive diagnostic cultures. For the specific list of Category A substances see the IATA document here (source:

Category B Biological Substances

Category B substances are considered a dangerous good, yet deemed somewhat less dangerous than Category A. Category B is broadly defined as an “infectious substance which does not meet the criteria for inclusion in Category A.”

Genetically Modified Organisms and Microorganisms (GMO/GMMOs)

GMMOs and GMOs are microorganisms or organisms in which genetic material has been purposely altered through genetic engineering in a way that does not occur naturally. These might meet previous definitions of Category A or Category B. If so, then classify them under those other categories — always according to the highest applicable risk.

Exempt Patient/Human/Animal Specimen

“Exempt” materials are a broad and common categorization, yet this category is often the most unfamiliar to many. Exempt materials are defined as “those collected directly from humans or animals, including, but not limited to, excreta, secreta, blood and its components, tissues and tissue fluid swabs, and body parts being transported for purposes such as research, diagnosis, investigational activities, disease treatment, and prevention.” IATA and the DOT don't want to overburden medical professionals shipping relatively benign samples, so these fall under more lax regulations. 

Some examples of Exempt Patient/Human/Animal Specimen: 

  • Routine testing of blood or urine tests ordered for a medical examination
  • Cholesterol, Blood Glucose
  • Insurance or employment tests
  • DNA tests
  • Pregnancy tests
  • Tests done for other than testing for the presence of pathogens
  • Patient specimens for which there is minimal likelihood that pathogens are present
  • Substances which do not contain infectious substances or substance which are unlikely to cause disease in humans or animals
  • Substances containing micro-organism which are non-pathogenic to humans or animals
  • Substances in a form that any present pathogens have been neutralized or inactivated such that they no longer pose a health risk (unless the chemical itself is regulated)
  • Environmental samples (including food and water) which are not considered to pose a significant risk of infection
  • Dried blood spots, collected by applying a drop of blood onto absorbent material
  • Fecal occult blood screening samples
  • Blood or blood components collected for transfusion or prep to be used for transfusion or transplantation; organs and tissues to be used in transplantation

If you’re unable to make a professional judgment on the presence of pathogens, don’t use the exempt classification and use the Category B classification unless the substance is listed on the Category A list. Just remember that triple packaging is still required. Learn more about exempt specimen shipments.


You’ve determined which classification best describes your material, now you’ve got to give it an official name and number. All dangerous goods are assigned both:

  1. Proper Shipping Name = PSN 
  2. United Nations Number = UN # 

Category A:

  • UN 2814 Infectious Substance Affecting Humans 
  • UN 2900 Infectious Substance Affecting Animals

Category B:

UN 3373 Biological Substance Category B

GMOs and GMMOs:

  • UN 3245 Genetically modified microorganisms 
  • UN 3245 Genetically modified organisms

Dry Ice:

  • UN 1845 Dry Ice

Exempt Human or Animal Specimen:

  • Exempt Human Specimen 
  • Exempt Animal Specimen 
  • There is no UN #

Examples of Identification

Let’s say you want to ship 5X5 mL of mouse blood for a routine blood chemistry panel:

  • Classification: Animal Specimen
  • PSN: Exempt Animal Specimen
  • UN #: N/A

Let’s say you want to ship 1mL of an E.Coli strain (K12) which has been genetically modified to produce a common human enzyme that is not hazardous:

  • Classification: GMMO
  • PSN: Genetically Modified Microorganism
  • UN #: 3245

You want to ship 1mL of human serum from a patient suffering from a genetic disease to see if an enzyme is present.

  • Classification: Patient Specimen
  • PSN: Exempt Patient Specimen
  • UN #: N/A

You want to ship 1mL of human serum from a patient suffering from a genetic disease to see if an enzyme is present. However, the patient has a known COVID-19 infection.

  • Classification: Category B Infectious Substance
  • PSN: Biological Substance, Category B
  • UN #: 3373

You want to ship 1mL of a S. pneumoniae strain which has been genetically modified:

  • Classification: Category B Infectious Substance
  • PSN: Biological Substance, Category B
  • UN #: 3373

You want to ship 1mL of a research stock culture with Rabies:

  • Classification: Category A Infectious Substance
  • PSN: Infectious Substance, Affecting Humans Category A
  • UN #: 2814

Remember: Always classify materials according to the greatest potential risk. Once you identify and classify your materials, see our article on packaging, shipping and documenting biological substances.

Cold Chain Logistics, Customs Documentation, Life Science Shipping

Differences Between UN 2814, UN 2900 and UN 3373

August 3, 2023

Shipping hazardous materials required understanding various classifications and regulations to ensure maximum safety. In biological substance shipping, the commonly referenced categories are UN 2814/UN 2900 (Category A) and UN 3373 (Category B).

Simplifying Shipping Since 1984

Request a quote today.

This website uses cookies. By accepting the use of cookies, this message will close and you will receive the optimal website experience. For more information on our cookie policy, please visit our Privacy Policy.