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 patu la, Organisms were exposed for 72 h to a low sublethal concentration (0.1 o f LC,,) using a semistatic contamination system; bioconcentration and elimi nation experiments were performed evaluating simultaneously acetylcholinest erase (ACHase) activity, The inhibition of the digestive gland ACHase reach ed 76% when the carbaryl concentration in tissue was 3.2 mu g/g. The increa sed enzyme inhibition was observed concomitantly with the bioconcentration of carbaryl until 7 h, ACHase inhibition was linearly dependent on the upta ke and bioconcentration of carbaryl (r(2) = 0.87). The transfer of snails t o carbaryl-free water after 72 h of exposure was followed by rapid monophas ic elimination with a half-life of 1.0 h. However, ACHase activity levels n ever returned to control values. These results revealed that the bioconcent ration might play a critical role in contributing to the toxicity of carbar yl. (C) 2000 Academic Press.