IQUIBICEN   23947
INSTITUTO DE QUIMICA BIOLOGICA DE LA FACULTAD DE CIENCIAS EXACTAS Y NATURALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effects of subchronic exposure to the organophosphate azinphos-methyl on the native gastropod Chilina gibbosa?
Autor/es:
BOBURG, B.; HERBERT, L.; COSSI, P.; LUQUET, C; KRISTOFF, G
Lugar:
Buenos Aires
Reunión:
Congreso; SETAC Latin America 11th Biennial Meeting: The Role of Science in Environmental Decision-Making; 2015
Institución organizadora:
SETAC Latinoamérica
Resumen:
Azinphos-methyl (AZM) is an organophosphate insecticide widely used in fruticulture. Maximum concentrations of 22 µg/L have been reported in Argentina?s freshwaters during application periods. Chilina gibbosa is a freshwater snail naturally exposed to this pesticide. Previous work published by our team found that Cholinesterases (ChEs) of this species are very sensitive to acute exposure to AZM. When snails were exposed to 20 µg/L, an inhibition of 85% of ChE activity and severe signs of neurotoxicity were observed. On the contrary, Carboxilesterases (CEs) were not modified. Our aim was to determine the effect of a sub-chronic exposure (21 days) to AZM on these biomarkers. To this end, 12 recipients containing 7 snails each were used: 6 solvent control recipients and 6 with AZM (20 µg/L). All recipients were oxygenated throughout the experiment. The snails were fed once a week and water was changed every 4 days, renewing the pesticide. On the 7th, 14th and 21st days we registered lethality and neurotoxicity signs, as well as ChE activity, using acetylthiocholine, and CE activity using p-nitrophenyl butyrate (p-NPB) and p-nitrophenyl acetate (p-NPA) as substrates. Lethality was observed on the 21st day with a loss of 18% of exposed snails. On the 7th day signs of neurotoxicity were observed: 90% of organisms lost adherence to the walls and 100% presented the cephalo-pedal region abnormally exposed. Also ChEs inhibition was more than 85%. None of the prior effects varied during the following days. CEs with both substrates were inhibited after 14 days of exposure (approximately 30% using p-NPB and 40% using p-NPA). Results suggest that an environmental concentration of AZM has a progressive effect that can be lethal. On the one hand, ChEs were strongly inhibited after 48 hours of exposure whilst CEs activity was affected after a longer period of exposure.