Toxicity of the nerve agent tabun to Daphnia magna, a new experimental species in military toxicology

Abstract

Daphnia magna, a freshwater microcrustacean, is currently tested as an alternative experimental species in research dealing with nerve agents poisonings treatment. Because of this, the toxicity of the nerve agent tabun (a cyanide-group containing organophosphate) to Daphnia had to be examined by estimating the EC₅₀ values. The immobilization of daphnids was chosen as the end-point. It was found that D. magna is sensitive to small amounts of tabun, even after 15 min exposure, and tabun toxicity increases with time. The estimated EC₅₀ values for 15, 30, 45, and 60 min exposure were as follows: 67.39, 38.10, 26.95, and 21.9 μg l⁻¹. In addition, the toxicity of media to which tabun was added 24 h before the start of experiments was examined. The results obtained indicate that daphnids can be used in experiments with nerve-agent intoxication treatment.

Keywords:

• Acetylcholinesterase
• Chemical warfare agents
• Cholinesterases
• Organophosphates
• Crustacean

Acknowledgements

We would like to thank Jiri Patocka and Koos (J.) Vijverberg for stimulating discussions and comments. The experiments described in this work were carried out in compliance with the current law of the Czech Republic. The work was supported by the grant of the Ministry of Defence, No. OBVRSVZDR200301.