Toxins of Biological Origin

Acute Toxins

Biological toxins are toxic substances produced by microorganisms, animals, and plants that have the capability of causing harmful effects when inhaled, ingested, injected or absorbed.  The health effects of exposure can vary greatly depending on the toxin, the amount, and the route of exposure, ranging from minor (skin or eye irritation, headache, nausea) to severe (respiratory distress, muscle weakness, seizures, death).

The Biosafety Office oversees the possession, use, and transfer of unfractionated mixtures and purified preparations of biological toxins with a mammalian LD50 £ 100 µg/kg body weight, as well as the organisms, both natural and recombinant, which produce these toxins.  These are referred to as “Acute Toxins.”   The Acute Toxin table lists numerous toxins that require registration based on known LD50 values (obtained from a variety of sources).  Please note that this list is not exhaustive and there may be other biological toxins with LD50 values < 100 µg/kg body weight that will require registration.  If you need additional guidance, please contact the Biosafety Office at 392-1591 or

Registration of Acute Toxin Projects

All research projects involving an acute toxin(s) must be registered with the Biosafety Office using the Acute Toxin Registration Form (updated 07/11/16).  In addition to the registration forms, you must also submit lab-specific Standard Operating Procedures (SOP template updated 07/07/16) for work with acute toxins at the time you submit your acute toxin registration document.  You cannot begin work with the toxin until your project and SOPs have been approved.

Note that the deliberate formation of recombinant or synthetic nucleic acid molecules containing genes for the biosynthesis of toxin molecules with an LD50 less than 100 ng/kg body weight (i.e. botulinum toxins, tetanus toxin, diphtheria toxin, and Shigella dysenteriae neurotoxin) is also subject to the NIH Guidelines and must be approved by NIH/OBA and the IBC prior to initiation. 

Toxins Classified as Select Agents

Some biological toxins are classified by the Federal Government as Select Agents due to their potential to pose a severe threat to public health and safety.  Possession, use and transfer of these toxins is highly regulated and all select agent toxins must be registered with the Biosafety Office.

Although they must still be registered by the Biosafety Office, in small quantities these select agent toxins are exempt from select agent regulations, provided the amount under control of a principal investigator, treating physician or veterinarian does not exceed, at any time or in any form, the amounts indicated in the table below. 


HHS Toxins Amount
Abrin 100 mg
Botulinum neurotoxins 0.5 mg
Short, paralytic alpha conotoxins 100 mg
Diacetoxyscirpenol (DAS) 1000 mg
Ricin 100 mg
Saxitoxin 100 mg
Staphylococcal enterotoxins (Subtypes A, B, C, D, and E) 5 mg
T-2 toxin 1000 mg
Tetrodotoxin 100 mg

Export Controlled Toxins

Several biological toxins are restricted for export by the U.S. Department of Commerce and require an export license prior to any shipment out of the U.S.  The list of toxins subject to export controls may be found on the Bioagent Export Control List.  All export-controlled toxins must be registered even if the LD50 of the toxin is > 100 µg/kg body weight.   For additional information, please visit the Office of Research, Division of Research Compliance Export Controls page or contact the Division of Research Compliance.