Biological hazard

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Biological hazards, also known as biohazards, refer to biological substances that pose a threat to the health of living organisms, primarily that of humans. This can include medical waste or samples of a microorganism, virus or toxin (from a biological source) that can impact human health. It can also include substances harmful to animals. The term and its associated symbol is generally used as a warning, so that those potentially exposed to the substances will know to take precautions.

In Unicode, the biohazard sign is U+2623 ().

Biohazardous agents are classified for transportation by UN number:

(Based on earlier edits)

  • UN 2814 (Infectious substance to Humans)
  • UN 2900 (Infectious substance to Animals)
  • UN 3291 (Medical Waste)


  • Category A, UN 2814- Infectious substances affecting humans and animals: An infectious substance in a form capable of causing permanent disability or life-threatening or fatal disease in otherwise healthy humans or animals when exposure to it occurs.
  • Category B, UN 2900- Infectious substances affecting animals only: An infectious substance that is not in a form generally capable of causing permanent disability of life-threatening or fatal disease in otherwise healthy humans and animals when exposure to themselves occurs.
  • Category B, UN 3373- Biological substance transported for diagnostic or investigative purposes.
  • Regulated Medical Waste, UN 3291- Waste or reusable material derived from medical treatment of an animal or human, or from biomedical research, which includes the production and testing of biological products.


Levels of biohazard

The United States' Centers for Disease Control and Prevention (CDC) categorizes various diseases in levels of biohazard, Level 1 being minimum risk and Level 4 being extreme risk. Laboratories and other facilities are categorized as BSL (Biosafety Level) 1-4 or as P1 through P4 for short (Pathogen or Protection Level).

  • Biohazard Level 1: Bacteria and viruses including Bacillus subtilis, canine hepatitis, Escherichia coli, varicella (chicken pox), as well as some cell cultures and non-infectious bacteria. At this level precautions against the biohazardous materials in question are minimal, most likely involving gloves and some sort of facial protection. Usually, contaminated materials are left in open (but separately indicated) waste receptacles. Decontamination procedures for this level are similar in most respects to modern precautions against everyday viruses (i.e.: washing one's hands with anti-bacterial soap, washing all exposed surfaces of the lab with disinfectants, etc). In a lab environment, all materials used for cell and/or bacteria cultures are decontaminated via autoclave.

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