Toxins of Biological Origin

Acute Toxins

Biological toxins are hazardous substances produced by microorganisms, animals, insects, and plants that can be harmful when inhaled, ingested, injected, or absorbed.  Depending on the toxin and amount and route of exposure, health effects can range from minor (skin or eye irritation, headache, nausea) to severe (respiratory distress, muscle weakness, seizures, death).

Toxins with a mammalian LD50 ≤100 µg/kg body weight, called “acute toxins”, pose the greatest risk. They are highly toxic in minute quantities, have no established safe exposure limits, and there is limited toxicological data applicable to human exposures.

Laboratory exposure risks are primarily from accidental injection, absorption through skin or mucous membranes, inhalation, and ingestion. Most acute toxins are stable proteins (or carbohydrates) requiring rigorous inactivation of contaminated surfaces, objects, and waste.

Higher risk procedures:

  • Use of aerosol or splatter generating procedures (e.g. vortexing, grinding, centrifuging, 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: potential for inhalation and a tendency for electrostatic attachment to gloves, weighing spatulas, etc.
  • Use of needles or sharps in experimental procedures
  • Reconstitution of lyophilized toxin:
    • Highly concentrated material
    • Sealed vials that are difficult to open (glass breakage, sharp metal band)
    • Removal of septa may result in dispersal of concentrated powder.
    • Alternatively, puncturing the septum with a needle and syringe provides potential for sharps injuries.

Registration of Acute Toxins

Reducing the risks associated with acute toxin work starts with the registration process.  All possession and use of acute toxin(s) must be registered with the Biosafety Office using the Gatot TRACS Biological Agent Registration.  Note that projects involving the deliberate formation of recombinant or synthetic nucleic acid molecules containing genes for the biosynthesis of toxin molecules with an LD50 < 100 ng/kg body weight (i.e. botulinum toxins, tetanus toxin, diphtheria toxin, and Shigella dysenteriae neurotoxin) must be approved by the NIH Office of Science Policy and the UF Institutional Biosafety Committee (IBC) prior to initiation. Lab-specific acute toxin Standard Operating Procedures (SOP template updated 07/07/16) must be submitted along with the acute toxin registration document.  Work cannot begin until  project registration and SOPs have been approved.

The Acute Toxin Table lists 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. Please contact the Biosafety Office at 392-1591 or

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 can be found on the Bioagent Export Control ListAll export-controlled toxins must be registered even if the LD50 of the toxin is > 100 µg/kg body weight.  This allows the Biosafety Office to track what laboratories are in possession of export-controlled material.

Toxins Classified as Select Agents

Some biological toxins are classified by the Federal Government as “Select Toxins” due to their potential to pose a severe threat to public health and safety.  Possession, use and transfer of these toxins is highly regulated.  All select toxins must be registered by the Biosafety Office. Please see the Select Agent page for more information on registering this work

In specified small quantities, select toxins are exempt from additional federal 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 (see also

HHS Toxins Amount

(New for 2017: The quantities able to be held and remain within the exclusion limit have increased for all but conotoxins)

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

NEW: Even in excluded amounts, select agent toxins are subject to federal regulations for “Due Diligence” when transferring any amount of select agent toxin to another investigator or individual.

Due to concerns that someone might stockpile select toxins, the law requires that any transferor must ensure and document that the recipient

  • Is eligible to receive the select toxin (is a principal investigator, treating physician or veterinarian, or commercial manufacturer or distributor).
  • Has a legitimate need (i.e., reasonably justified by a prophylactic, protective, bona fide research, or other peaceful purpose) to handle or use such select toxins.
    • Because each PI must register the possession and use of acute toxins, including select toxins, the transfer of select toxins to another UF PI must be approved in advance by the Biosafety Office, who will verify as part of the registration process, that the recipient PI has a legitimate need to possess the material.
    • Transfer of select toxins outside of UF must also be approved in advance by the Biosafety Office. In addition to documenting the recipient’s legitimate need, the Biosafety Office will assist with shipping the toxin (also strictly regulated).
  • Provide the Biosafety Office with:
    • The recipient’s identity information, including the recipient’s name, institution name, address, telephone number, and email address.
    • The name of the toxin and total amount transferred.
    • The legitimate need claimed by the recipient.

Lastly, transferors must report known or suspected violations of Federal law or suspicious activity related to select toxins to the Biosafety Office or 352-392-1591 or federal authorities by emailing to CDC: or APHIS: or calling FSAP (CDC: 404-718-2000 or APHIS: 301-851-3300 (option 3).

Acute Toxin Risk Assessment

At the time of registration or shortly thereafter, Biosafety Office staff will conduct a lab inspection as part of their risk assessment. Initial and follow up inspections are done to ensure the mitigations listed below, as well as any specified in the project approval letter are in place:

Security measures

Due to their high hazard and potential for misuse, access to acute toxins must be restricted. Keep only minimal amounts on hand. Toxin storage must be locked and access controlled by the PI or their designee. Toxin usage is tracked from receipt to destruction in a secure inventory log. Report suspicious activities or security concerns to the University Police.


All persons with potential exposure to toxins must be familiar with the Safety Data Sheet (SDS) supplied by the manufacturer and must also read and sign the lab-specific acute toxin SOPs indicating that they understand them. SOPs will cover both experimental procedures with toxins as well as emergency procedures. SOPs are to be updated and re-read as changes are made and reviewed by all at least annually.

Hazard Warnings

Biohazard warning labels shall be used to designate areas or items where toxins may be present. A sign stating “Toxin in Use Do Not Enter” shall be posted when toxins are being manipulated.

Engineering Controls

A functional and certified fume hood or biosafety cabinet (never a laminar flow “clean bench”) shall be used whenever:

  • There is a potential for aerosols, splashes, or splatters
  • When open manipulation of toxin solutions occurs
  • When reconstituting stock vials
  • When opening toxin packages shipped to the lab

Other engineered safety devices:

Safe Work Practices

Use the “Buddy System” when working with concentrations or amounts near or exceeding the LD50 dose for a human or when conducting higher risk procedures

Limit glassware (no glass Pasteur pipettes)

Work over disposable, absorbent paper

Use disposable containers

Have sharps boxes and spill kits at the ready

Store and transport toxin in a minimum of 2 layers of sturdy, leak-proof packaging

Personal Protective Equipment (PPE)

Long pants and full-coverage shoes

Disposable lab coat or gown

2 pair gloves

Face and eye protection: goggles and facemask or equivalent

Decontamination Method

The appropriate disinfectant or decontamination method is critical since toxins may be resistant to common disinfectants and autoclaving is not an effective method for low molecular weight toxins (e.g. marine toxins or mycotoxins).  Exposure to strong bleach or sodium hydroxide for a minimum of 60 minutes is generally sufficient. Inactivated waste shall be handled as hazardous waste and picked up for disposal by EHS.

Occupational Health

In accordance with CDC BMBL and ACIP guidance, the BioSafety Office strongly recommends TDaP vaccination for individuals who work directly with tetanus, diphtheria or pertussis toxins and/or toxin-producing strains of Clostridium tetani, Corynebacterium diphtheriae, or Bordetella pertussis. The vaccine is available through UF’s Occupational Health Clinic, part of the SHCC. Boosters are required at least every 10 years.

Exposure Management

Skin or Wound Exposures:

  • Move to (or move person to) an uncontaminated area.
  • Remove contaminated clothing and place in red biohazard bag for decontamination.
  • Wash skin and wound exposures with fresh 0.5% sodium hypochlorite or soap and water.
  • For spills of large quantities of toxin onto clothing or skin, immediately use the emergency shower and follow with fresh 0.5% sodium hypochlorite or soap and water.

Eye or Mucous Membrane Exposure:

  • Use emergency eyewash for a minimum of 15 minutes.

In all instances:

  • Obtain medical attention as required:
    • For a life-threatening emergency, call 911.
    • If non-life threatening, contact AmeriSys at 1-800-455-2079 for authorization on where to receive medical treatment.
  • Review the SDS for symptoms of exposure or delayed onset effects.
  • Report Incident to Supervisor and Biological Safety Office (392-1591).


“Safety and Health Considerations for Conducting Work with Biological Toxins”, Johnson, Mastnjak, and Resnick; Applied Biosafety, 6(3) pp. 117-135, 2001

Biosafety in Microbiological and Biomedical Laboratories (BMBL) 5th Edition

Updated 01/17/20