In vitro and in vivo inhibition of Daphnia magna acetylcholinesterase by surfactant agents: possible implications for contamination biomonitoring

This study was designed to investigate the effect of two surfactants, dodecyl benzyl sulfonate DBS., sodium dodecyl sulfate SDS., and of a domestic detergent Y. on the AChE activity of the crustacean cladoceran Daphnia magna. All the chemicals significantly inhibit the activity of the enzyme, both in vitro and in vivo conditions. In vitro lowest observed effect concentration LOEC. values ranged from 12.5 to 100 mgrl and correspondent IC50 50% inhibition concentration. values ranged from 6.6 to 58.5 mgrl. In vivo LOEC values ranged from 2 to 11.9 mgrl, while EC50 50% effect concentration. values ranged from 11.4 to 56.7 mgrl. AChE inhibition by environmental contaminants such as surfactants, detergents and metals may lead to false diagnostics and even wrong conclusions in biomonitoring studies based on the use of AChE as a specific biomarker for organophosphorous and carbamate compounds.