44G-2 |
Potential use of blood cholinesterase in monitoring exposure of beef cattle to organophosphate pesticides |
V. T. PARDIO1, K. N. Waliszewski2, N. Ibarra3, and B. Nochebuena3. (1) Facultad de Medicina Veterinaria y Zootecnia, Universidad Veracruzana, Avenida Circunvalación esq. Yáñez s/n, Veracruz, 91710, Mexico, (2) UNIDA, ITV, Veracruz, Mexico, (3) FMVZ, UV, Veracruz, Mexico Organophosphate pesticides (OPs) are intensively used to promote animal health in tropical areas. These pesticides are present for only short intervals, thus expensive techniques are used to determine their concentration. Erythrocyte cholinesterase activity correlates to brain cholinesterase activity, the site of action of OPs. Authors have determined the mean baseline cholinesterases activities for mature beef cattle produced in tropic zones. Since the ingestion of meat containing these chemicals represents a health hazard, a reliable method to assess beef cattle exposure to OPs is needed. The purpose of the study was to determine the potential application of blood cholinesterase inhibition as a cost-effective screening method to monitor beef cattle exposure to OPs. Fifty mature male steers Cebu/Swiss were sampled from three production zones located at the Southern and Central areas of Veracruz Mexico. Animals were sprayed with Coumaphos at different time intervals for thick control. Determination of cholinesterase activity was according to a Ellman method modified by authors. Multivariate analysis showed that cholinesterase and acetylcholinesterase activities differed significantly between sampling sites. The whole blood and plasma cholinesterase and acetylcholinesterase activities were significantly lower than the mean baseline activities. Mean erythrocyte cholinesterase and acetylcholinesterase activities represented 98.9% and 50.4% of the whole blood activity, respectively. The erythrocyte cholinesterase and acetylcholinesterase activities correlated to medulla oblongata acetylcholinesterase activity (r2=0.9162, 0.7819) and were significantly depressed in the animals from the central area (37.6%, 67.7%) compared to southern groups (15.7%, 21.0%). Animals from central area were sprayed every 14 days and the other two groups every 21 days. These observations suggested that the decreased erythrocyte cholinesterases activities reflected OPs contamination. Among blood samples studied, the erythrocyte cholinesterase and acetylcholinesterase activities could constitute an appropriate parameter for assessing exposure of cattle to OPs. This is consistent with WHO recommendations in human studies.
Session 44G, Toxicology & Safety Evaluation
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