Toxicity toward D. magna was mainly due to the adverse effects of quinine. An additional chronic toxicity test against D. magna, performed for the least harmful QAS with a 1butylquinium cation and an L-asparaginate anion, showed no long-term effects at concentrations of 0.1 mg dm -3 and below. Surprisingly, at sublethal concentration (10 mg dm -3 ), inhibition of the chronic toxicity of this salt and positive effects on the reproduction of test organisms were observed.