ABSTRACT
In the wake of terrorist-related incidents across the globe, biological agents have become known for the threat they pose to US and Allied militaries as well as the civilian populations they defend. Toxins are produced by a vast number of different life forms, ranging from the simplest to the most complex, and each toxin has a distinctive mode of action in conjunction with a characteristic molecular structure and biochemistry. One of the most extensively studied protein families in biology is that of the ribosome-inactivating proteins, a large family of protein toxins and related proteins that includes ricin. Many pathogens and toxins cause disease, toxicity, or other deleterious effects, relatively few of the naturally occurring agents can be adapted for use as a biological weapon. Biological select agents and toxins deposition in the respiratory tract is largely dependent on particle size, but other factors can also become important.
