The natural bioluminescence of the microscopic marine dinoflagellate alga, Pyrocystis lunula, is quenched measurably in the presence of toxins. This principle, trade-named Lumitox, was employed in the development of a portable, hand-held instrument trade-named TOX-BOY, in response to a solicitation by the United States Army for a rapid field toxicity test for water supplies. TOY,-BOX is capable of detecting dangerous concentrations of toxins in most environmental media. Portable, Water, Toxicity, ...