Relationship between toxicokinetics of carbaryl and effect on acetylcholinesterase activity in Pomacea patula snail

The 96-h LC50 value of carbaryl aas 14.6 mu g/mL for the snail Pomacea patula, Organisms were exposed for 72 h to a low sublethal concentration (0.1 of LC,,) using a semistatic contamination system; bioconcentration and elimination experiments were performed evaluating simultaneously acetylcholinesterase (ACHase) activity, The inhibition of the digestive gland ACHase reached 76% when the carbaryl concentration in tissue was 3.2 mu g/g. The increased enzyme inhibition was observed concomitantly with the bioconcentration of carbaryl until 7 h, ACHase inhibition was linearly dependent on the uptake and bioconcentration of carbaryl (r(2) = 0.87). The transfer of snails to carbaryl-free water after 72 h of exposure was followed by rapid monophasic elimination with a half-life of 1.0 h. However, ACHase activity levels never returned to control values. These results revealed that the bioconcentration might play a critical role in contributing to the toxicity of carbaryl. (C) 2000 Academic Press.