Biotoxins are poisonous substances produced by living organisms (animals, plants, microbes) and are not man-made. Unlike most other biohazards, biotoxins do not replicate and, in certain respects, are comparable to classic organic chemicals. However, biotoxins differ from chemical toxins in that they do not pose a vapor hazard and few are dermally active (mycotoxins are the exception).
The Institutional Biosafety Committee (IBC) regulates the possession, use, and transfer of biological toxins with a mammalian LD50 of ≤ 100 mg/kg and the organisms that produce these biological toxins. More information and registration can be found on the Institutional Biosafety Committee Program page.
A risk assessment involving biotoxins takes into consideration:
The risk assessment defines the biosafety/containment level for work with the biotoxin and is a combination and integration of administrative controls, engineering controls, work practices, and PPE that mitigates the risk to an acceptable level.
Biotoxins with an LD50 < 50 mg/kg (e.g., cholera toxin, microcystin, aflatoxin, and ricin) are classified as risk group 2 biotoxins requiring Biosafety Level 2 containment. Biotoxins with an LD50 >50 mg/kg, such as Lipopolysaccharide (LPS), may be downgraded to Biosafety Level 1 depending on the procedures and how the biotoxin is being used.
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 are highly regulated; a complete list can be found at http://www.selectagents.gov/. In small quantities (see below), some of these toxins are exempt from Select Agent registration but must still be registered with the IBC:
Proper handling of biotoxins poses special challenges but is vital for protecting laboratory and service personnel.
Biotoxins are frequently stored in a lyophilized powdered form. Commercial preparations typically are shipped in crimped vials that are topped by a rubber stopper, while the individual laboratory may package and store the powder in vials or microcentrifuge tubes. Solubilizing the powder to formulate a stock solution presents a risk to the researcher because of the possibility of dispersal of the powder into the air. The protocols below are designed to minimize the risk of personnel exposure and environmental contamination.
When preparing biotoxin stock solution in crimped vials:
Biotoxin stock solution preparation in microcentrifuge tubes: