Biological toxins are poisonous substances produced by certain microorganisms, animals, and plants. Examples of toxins of biological origin include Diphtheria Toxin, Tetrodotoxin, Pertussis Toxin, Botulinium Toxin, Snake Venom Toxins, Conotoxin and Ricin. Although toxins are derived from biological materials, they do not replicate and are therefore not considered infectious. However, they may be extremely toxic in very small quantities and must be managed like hazardous chemicals in the workplace.
Controls must be in place to ensure staff are protected from exposure. The routes of exposure include inhalation, eye, nose and mucous membrane contact, percutaneous, and skin absorption depending on the diluents used. The main issues of concern in the laboratory are accidental exposures to toxin caused by contact with the mouth, eye, skin and mucous membranes, inhalation of toxin powder or aerosol inadvertently generated, or by needlestick incidents.
Work with toxins of biological origin requires documented laboratory-specific training on standard operating procedures (SOP) for all laboratory personnel prior to starting work. The training must include, but is not limited to, the health and physical hazards of the toxin, signs and symptoms associated with exposure, appropriate work practices, personal protective equipment, emergency procedures, and reporting of personnel exposures.
Some biological toxins are considered Select Toxins, which the Federal Select Agent Program has identified as a severe threat to public health and safety as bioterrorism agents. Transfer, possession, use, and disposal of all of these agents and toxins are strictly regulated. Certain toxins used in quantities below regulatory thresholds may be excluded from the requirements of Select Agent Regulations. See the following CDC link for the current list of Select Toxins, exclusions and exempt quantities. http://www.selectagents.gov. Please see chapter 14 of the BSM manual for more specific information regarding Select Toxins.
Laboratory Planning and Preparation of Use
- The use of biological toxins requires submittal of a biological use agreement (MOUA) for approval by the IBC.
- Develop a written laboratory-specific SOP that is specific to the toxin and the procedure being used. A Biological Toxin SOP template with a training documentation form is available.
- Provide documented laboratory-specific training to personnel working with toxins, and any other personnel authorized or required to be in the laboratory during toxin work.
- Ensure the toxin Material Safety Data Sheet/Safety Data Sheet (MSDS/SDS) is available to staff at all times.
- Designate toxin storage area (freezer, refrigerator, cabinet or other container) in a secure location.
- Select toxins must be maintained in a locked location. See chapter 14 for additional details on select toxins
- Designate a specific area within the laboratory where toxin use will take place. There may be a need for ventilated containment depending on the likelihood of inhalation. If working with a toxin in powder form, a BSC, glove box, fume hood, or other approved form of containment will need to be utilized.
- Prepare a sign stating “Toxins in Use” and post in the area that is designated for toxin use. When the toxin is in use, this sign should be posted and lab personnel should be notified that the toxin is in use.
- If possible, do not work with toxin in solid or powder form. If it is necessary to purchase it in powder or solid form, purchase pre-diluted or pre-weighed toxin in the minimum quantity needed to perform work. Introduce the diluent through the septum in a way that eliminates the needs to open the septum (e.g., injection of diluent through a rubber septum).
- If the toxin must be weighed, use ventilated containment to weigh out the toxin. The tare method can be used to prevent inhalation of the toxin.
- Tare method – While working in a laboratory hood, the chemical is added to a pre-weighed container. The container is then sealed and re-weighed outside of the hood. If chemical needs to be added or removed, this manipulation is carried out in the hood. In this manner, all open toxin handling is conducted in the laboratory hood.
- Determine the appropriate chemical and/or physical inactivation method(s) for the specific toxin (refer to toxin inactivation). Ensure supplies for inactivation of toxin are readily available.
- Ensure supplies for spill cleanup are appropriate for the specific toxin, maintained in a clearly marked spill cleanup kit and readily available in the laboratory.
Consider the toxin properties when selecting a containment device. Designate a certified BSC, glove box, fume hood, or other containment device for toxin use. A clean bench should never be used for work with biological toxins since it provides no personnel protection from the hazards of the toxin in use.
In-line HEPA filters are required if vacuum lines are used with a toxin.
If centrifugation will take place while working with a biological toxin, then safety cups and sealed rotors must be used and the outside of surfaces routinely decontaminated. The rotors and safety cups should only be opened inside a certified BSC or other form of containment.
Personal Protective Equipment
Safety glasses with a side shield or goggles should be worn.
Wear a long sleeved lab coat, a smock, or coveralls. Consider using disposable PPE.
Gloves that are impervious to the toxin and to the diluent need to be specially selected. Double gloving is recommended. Gloves need to be changed immediately if they become contaminated, punctured, or torn and disposed of immediately after removal.
Wear additional face protection, such as a face shield, when splash or splatter is possible.
Respiratory protection may be required if an airborne hazard is present. Notify the biosafety officer if respiratory protection is required. Laboratory personnel will need to undergo a medical evaluation and have a fit test performed by EH&S personnel as part of the UNR respiratory protection program.
- Work with toxins in a designated area. This can be done by posting a sign during work or more permanent marking can be in place if the work takes place routinely.
- Biosafety Level 2 (BSL-2) practices are appropriate for most toxin work. However, some toxins or procedures may require additional safety precautions (BSL2+ or BSL3).
- Work with toxin in a BSC, fume hood, glove box or other approved containment if it is appropriate to do so pending the determinations made following a risk assessment.
- Transport toxins only in labeled, leak/spill-proof, non-breakable secondary containers.
- Perform preparations over plastic backed laboratory diapers that have been presoaked with the appropriate inactivating agent (refer to toxin inactivation). Dispose of lab diapers after completion of tasks or immediately upon contamination.
- Eliminate the use of sharps whenever possible. Utilize safe sharps procedures (i.e., sharps container in the immediate vicinity). Safety needles, to include needle locking syringes and disposable syringe needle units are recommended and should be disposed of promptly after use. Never bend, break, or recap a needle.
- If biological toxins are administered to research animals, restrain or anesthetize animals when possible.
- Decontaminate containers before they are removed from the fume hood, BSC, or glove box. Also decontaminate the exterior of the closed primary container and place it in a clean secondary container.
- Upon completion of tasks, thoroughly decontaminate the BSC or approved containment and all surfaces using an appropriate inactivating agent and contact time.
- All potentially contaminated disposable items (such as gloves used in preparation) must be placed in a hazardous waste bag and autoclaved before disposal.
- Thoroughly wash hands after work has been completed as is the standard practice for BSL-2 work.