Toxicological Effects of Military Smokes and Obscurants on Aquatic Threatened and Endangered Species

This research report describes actual field deposition and laboratory bench-scale applications of military smokes and obscurants (S&O) onto aquatic surfaces to study direct and indirect toxicological effects on threatened and endangered fish species, surrogate fish species, insect prey and aquatic plant habitat. Data allow predictions of impacts, effects, and mortality on relevant aquatic species from exposure to varying concentrations of S&O. Insect prey mortality is observed during relevant field deposition while heavier doses are required to induce lethal and sub-lethal effects on higher order organisms. Modes of toxicity include both direct contact of an organism with surface films and chemical transformation of S&O components into more toxic byproducts via photolytic mechanism upon exposure to sunlight. Recommendations for S&O field use are provided based on conservative estimates of chemical deposition from environmental release of S&O during military training exercises.