Stanford University

List of Select Agents and Toxins

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Select Agents and Toxins are subject to stringent regulatory requirements under 42 CFR 73 for their potential to pose a severe threat to public, animal or plant health or to animal or plant products. These toxins are indicated in the list below.

Experiments involving any of the following are also regulated:

  1. ​Nucleic acids that can produce infectious forms of any of the select agent viruses.
  2. Recombinant nucleic acids that encode for the functional form(s) of any of the select agent toxins if the nucleic acids: a) can be expressed in vivo or in vitro; or b) are in a vector or recombinant host genome and can be expressed in vivo or in vitro.
  3. Select agents that have been genetically modified.
  1. ​Experiments utilizing recombinant DNA that involve the deliberate transfer of a drug resistance trait to the listed agents that are not known to acquire the trait naturally, if such acquisition could compromise the use of the drug to control disease agents in humans, veterinary medicine, or agriculture.
  2. Experiments involving the deliberate formation of recombinant DNA containing genes for the biosynthesis of listed toxins lethal for vertebrates at an LD50 < 100 ng/kg body weight.


The following select agents or toxins are exempt:

  • Any select agent or toxin that is in its naturally occurring environment provided it has not been intentionally introduced, cultivated, collected, or otherwise extracred from its natural source.
  • Non-viable select agent organisms or nonfunctional toxins.
  • Toxins under the control of a principal investigator, treating physician or veterinarian, or commercial manufacturer or distributor, if the aggregate amount does not, at any time, exceed the amount listed in parenthesis next to the toxin.
  • Medical use of toxins for patient treatment.
  • Additional exemptions are listed on the CDC website.


* A virulent Newcastle disease virus (avian paramyxovirus serotype 1) has an intracerebral pathogenicity index in day-old chicks (Gallus gallus) of 0.7 or greater or has an amino acid sequence at the fusion (F) protein cleavage site that is consistent with virulent strains of Newcastle disease virus. A failure to detect a cleavage site that is consistent with virulent strains does not confirm the absence of a virulent virus.

** Short, paralytic alpha conotoxins containing the following amino acid sequence: X1CCX2PACGX3X4X5X6CX7

*** Tier 1 agents

α APHIS Plant Pathogen

ψ HHS Select Infectious Agent

β USDA High Consequence Livestock Pathogen or Toxin

χ USDA-HHS Overlap Agent

African horse sickness virus β
African swine fever virus β
Avian influenza virus (highly pathogenic) β
Classical swine fever virus β
Crimean-Congo haemorrhagic fever virus ψ
Eastern equine encephalitis virus ψ
Ebola virus*** ψ
Foot and mouth disease virus*** β
Goat pox virus β
1918 influenza virus ψ
Lassa fever virus ψ
Lujo virus ψ
Lumpy skin disease virus β
Marburg virus*** ψ
Monkeypox virus ψ
Newcastle disease virus (virulent)* β
Nipah and Hendra complex viruses χ
Peste des petits ruminants β
Rift Valley fever virus χ
Rinderpest virus*** β
Sheep pox virus β
South American haemorrhagic fever virus [(Chapare, Guanarito Junin, Machupo, Sabia)] ψ
Swine vesicular disease virus β
Tick-borne encephalitis virus [Far Eastern subtype, Siberian subtype, Kyasanur Forest disease virus, Omsk Hemorrhagic fever virus)] ψ
Variola major virus (Smallpox virus) and Variola minor virus (Alastrim)*** ψ
Venezuelan equine encephalitis virus χ
Abrin (>1,000 mg) ψ
Botulinum neurotoxins (>1 mg)*** ψ
Short, paralytic alpha conotoxins (>100 mg) ψ**
Diacetoxyscirpenol (DAS) (>1,000 mg) ψ
Ricin (>1,000 mg)ψ
Saxitoxin (>500 mg) ψ
Staphylococcal Enterotoxins (Subtypes A-E) (> 100 mg) ψ
T– 2 toxin (>10,000 mg) ψ
Tetrodotoxin ( >500 mg) ψ
Bacillus anthracis*** χ
Botulinum neurotoxin producing strains of Clostridium*** ψ
Brucella abortus χ
Brucella melitensis χ
Brucella suis χ
Burkholderia mallei*** χ
Burkholderia pseudomallei*** χ
Coxiella burnetii ψ
Francisella tularensis*** ψ
Mycoplasma capricolum/capripneumoniae (contagious caprine pleuropneumonia) β
Mycoplasma mycoides mycoides (MmmSC)(contagious bovine pleuropneumonia agent) β
Ralstonia solanacearum race 3, biovar 2 α
Rathayibacter toxicus α
Rickettsia prowazekii ψ
Xanthomonas oryzae α
Yersinia pestis*** ψ
Peronosclerospora philippinensis (Peronosclerospora sacchari) α
Phoma glycinicola α
Sclerophthora rayssiae var zeae α
Synchytrium endobioticum α
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