Public health agencies and environmental protection organizations classify numerous hazardous substances among the most toxic compounds known to science due to their extreme lethality and environmental persistence. Notable examples include botulinum toxin, tetrodotoxin, ricin, VX nerve agent, sarin, cyanide compounds, mercury and organic mercury derivatives, arsenic, polychlorinated biphenyls (PCBs), and radioactive isotopes like plutonium. Exposure to even microscopic quantities of these hazardous substances can cause catastrophic systemic organ failure or rapid fatality.