Biological toxins are poisonous substances, either naturally produced by an animal, plant or microbial source; or their analogs may be synthesized in a laboratory. Unlike most other biohazards, biotoxins cannot replicate, and they are not infectious. However, these toxins can be harmful at relatively low levels when inhaled, ingested, injected, or absorbed through the skin or mucous membranes.  Depending on the toxin, amount, and route of exposure, health effects can range from minor (skin or eye irritation, headache, nausea) to severe (respiratory distress, muscle weakness, seizures, paralysis, death). Unlike most hazardous chemicals, biological toxins have no established safe exposure limits, and there is limited toxicological data applicable to human exposures.

Biotoxin Registration

Please include ALL toxins in your laboratory HCOC online inventory. In the case of an emergency in the lab, EH&S staff need to be able to communicate all potential hazards to emergency responders. For acute toxins and exempted select agents, please record all quantities procured and used, as well as volumes and concentrations of any diluted stocks using the Toxin Tracking Form (DOC).

IBC Review

Toxins with a mammalian LD50* of 100 mg/kg (100,000 µg/kg) or less are considered acute toxins, and their use must be administratively reviewed by the IBC. Biohazardous Agent Reference Documents (BARDs) will also be required for labs using acute toxins.

*LD50 (Lethal dose) is the amount of an ingested substance that kills 50 percent of a test population. It is generally expressed as a unit of substance per kilogram of body weight.

LD50 values for some commonly used biotoxins
Toxin LD50 (micrograms/kg)
Abrin 0.7
Aerolysin 7
Botulinum toxin A 0.0012
Botulinum toxin B 0.0012
Botulinum toxin C1 0.0011
Botulinum toxin C2 0.0012
Botulinum toxin D 0.0004
Botulinum toxin E 0.0011
Botulinum toxin F 0.0025
b-bungarotoxin 14
Caeruleotoxin 53
Cereolysin 40 - 80
Cholera toxin 250
Clostridium dificile enterotoxin A 0.5
Clostridium dificile cytotoxin B 220
Clostridium perfringens lecithinase 3
Clostridium perfringens kappa toxin 1500
Clostridium perfringens perfringolysin O 13 - 16
Clostridium perfringens enterotoxin 81
Clostridium perfringens beta toxin 400
Clostridium perfringens delta toxin 5
Clostridium perfringens epsilon toxin 0.1
Conotoxin 12 - 30
Crotoxin 82
Diphtheria toxin 0.1
Listeriolysin 3 - 12
Leucocidin 50
Modeccin 1 - 10
Nematocyst toxins 33 - 70
Notexin 25
Pertussis toxin 15
Pneumolysin 1.5
Pseudomonas aeruginosa toxin A 3
Ricin 2.7
Saxitoxin 8
Shiga toxin 0.25
Shigella dysenteriae neurotoxin 1.3
Staphylococcus enterotoxin B 25
Staphylococcus enterotoxin F 2 - 10
Streptolysin O 8
Streptolysin S 25
Taipotoxin 2
Tetanus toxin 0.001
Tetrodotoxin 8
Viscumin 2.4 - 80
Volkensin 1.4
Yersinia pestis murine toxin

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Please note that this list is not exhaustive and there may be other biological toxins that will require registration. Please contact the Biosafety Office with any questions.

Select Agents

Some biological toxins are classified by the CDC and USDA as Select Agents, due to their potential to pose a severe threat to public health and safety. Select Agents are highly regulated and their use, possession, and transfer requires registration with the Federal Select Agent Program (FSAP).

UVM is not registered with the FSAP, and therefore only exempted amounts of select agent toxins (as defined below) are allowed in our laboratories.

The following select agent toxins are not regulated if the amount under the control of a principal investigator, treating physician or veterinarian, or commercial manufacturer or distributor does not exceed, at any time, the amounts indicated in the table below:

Select Agent Toxin Permissible Amount
Abrin 1000 mg
Botulinum neurotoxins 1 mg
Short, paralytic alpha conotoxins 100 mg
Diacetoxyscirpenol (DAS) 10,000 mg
Ricin 1000 mg
Saxitoxin 500 mg
Staphylococcal enterotoxins (subtypes A, B, C, D, and E) 100 mg
T-2 toxin 10,000 mg
Tetrodotoxin 500 mg

The possession, use, or transfer of ANY select agent toxin, IN ANY QUANTITY, must be registered with the Biosafety Office. Select Agent Toxins require detailed inventories to ensure that total quantities remain below the regulated amount. Select Agent Toxin inventories should include date and quantity of each acquisition (purchase, transfer, etc.), use and disposal.

Please use the UVM Biotoxin Tracking Form (DOC) to track your exempted select agent toxin usage.

Safe Handling

Laboratory exposure risks are primarily from accidental injection, absorption through skin or mucous membranes, inhalation, and ingestion. Typically, the amounts used in biomedical research laboratories can be handled safely by trained laboratory personnel. Handling of concentrated stocks poses the greatest risk to laboratory personnel. Even a seemingly tiny quantity of concentrated toxin may contain more than a lethal dose for a human.

Preparation of biotoxins should be performed in a Biosafety Cabinet or Chemical Fume Hood while wearing a lab coat/gown and gloves, and may also require the use of respiratory protection. The use of latex gloves should be avoided, as they may not be impervious to all dermal hazards. When handling powdered toxins, select gloves that do not generate static electricity. For most toxin use, standard BSL-2 practices should be followed unless otherwise indicated by the Biosafety Office.

Higher risk procedures:

  • Use of aerosol or splatter generating procedures (e.g. vortexing, grinding, centrifuging, injection or intra-nasal inoculation of animals).
  • Utilization of concentrated stocks or large quantities of toxins: beware that a vial could contain more than a LD50 for an average-sized person! Calculate in advance.
  • Work with powdered or dried toxins, reconstitution of lyophilized toxin: highly concentrated material with high potential for inhalation and a tendency for electrostatic attachment to gloves, weighing spatulas, etc.
  • Use of needles or sharps in experimental procedures


Store toxin stocks in secured storage rooms, cabinets, or freezers with restricted access. If toxins are stored in the laboratory, containers should be sealed, labeled, and secured to restrict access.

Inactivation and Disposal

Most acute toxins are stable proteins (or carbohydrates) requiring rigorous inactivation of contaminated surfaces, objects, and waste. Addition of a sodium hypochlorite solution is one of the easiest ways to inactivate many biotoxins. The final concentration for inactivation should be 50% bleach, or 2.5% sodium hypochlorite. Autoclaving for 60 minutes may also be effective, depending on the toxin. Alternative chemical destruction methods can be found in the BMBL, Appendix I (PDF). Make sure to check the toxin's SDS for recommended inactivation methods. Chemical inactivation procedures must be performed in a Biosafety Cabinet or Chemical Fume Hood while wearing the appropriate PPE.