U.S. Environmental Protection Agency


Date of this Version



Published in Cyanobacterial Harmful Algal Blooms: State of the Science and Research Needs, ed. H. Kenneth Hudnell (Springer, 2008).


The United States is faced with having to address critical issues that have not been addressed in the past, as recent security interests have placed new and more pressing demands on the assessment of risk from exposure to potential threats resulting from deliberate contamination. Such assessments are the basis for decisions about future research priorities, actions taken to prevent intentional contaminant releases, and developing detailed plans for response if such an event was to occur. High fidelity assessments are based on robust knowledge of the numerous parameters that can be used to predict the fate, transport, persistence, and toxicity for contaminants under numerous circumstances. Therefore, identification and determination of these parameters are the primary steps for evaluation of potential threats.
Numerous toxic substances exist, but very few have the potential to cause mass casualties from widespread contamination. Conventional chemical and biological weapons have strict laws that control their possession, transport, and use. Military studies of conventional agents have identified and determined many of the parameters necessary for accurate threat assessments. Spanning the threat space between chemical and biological weapons are biotoxins. Biotoxins are chemical toxins that are of natural biological origin. These compounds also have unique physio-chemical properties compared to other chemical and biological agents. Most natural toxins have few controls over possession, transport, and use; thus, these biotoxins have greater potential availability than conventional threat agents. They can range from large proteins (10s to 100s kDa) to small molecular weight molecules (~100- ~500 MW). Large biotoxins must be extracted from biological material, but the small molecular weight toxins can be obtained either through biological extraction (Barros et al. 2004) or through methods for direct chemical synthesis published in scientific journals (Kishi et al. 1977; Jacobi et al. 1984; Mansell 1996).