Daphnia intoxicated by nerve agent tabun can be treated using human antidotes

Application of human antidotes against nerve agent intoxications to microcrustacean Daphnia magna (Crustacea, Cladocera) intoxicated by a nerve agent tabun (O-ethyl-N,N-dimethylphosphoramidocyanidate) and their efficacy was investigated. It was found that antidotes can be successfully applied to intoxicated daphnids. Three different treatment regimens were tested: the combination of atropine and acetylcholinesterase reactivator (trimedoxime was chosen), atropine only and trimedoxime alone, too. The most efficient was the combination of atropine and trimedoxime followed by treatment with atropine only. The proportion of recovered animals increased with time not only in treated groups but also in the control as well. This can be explained by a spontaneous reactivation of tabun-inhibited cholinesterase in daphnids probably indicating a difference between mammalian and crustacean cholinesterases.