RESUMEN
Four veterinary drugs of dissimilar chemical structures were evaluated for environmental stability and penchant for bioaccumulation. The techniques used were (1) a model aquatic ecosystem (3 days) and (2) a model feedlot ecosystem (33 days) in which the drugs were introduced via the excreta of chicks or mice. The model feedlot ecosystem was supported by metabolism cage studies to determine the amount and the form of the drug excreted by the chicks or mice. Considerable quantities of all the drugs were excreted intact or as environmentally short-lived conjugates. Diethylstilbestrol (DES) and Clopidol were the most persistent molecules, but only DES bioaccumulated to any appreciable degree. Phenothiazine was very biodegradable; sulfamethazine was relatively biodegradable and only accumulated in the organisms to very low levels. Data from the aquatic model ecosystem demonstrated a good correlation between the partition coefficients of the drugs and their accumulation in the fish.
Asunto(s)
Clopidol/metabolismo , Dietilestilbestrol/metabolismo , Fenotiazinas/metabolismo , Piridinas/metabolismo , Sulfametazina/metabolismo , Animales , Pollos , Chlorophyta , Clopidol/toxicidad , Culex , Ciprinodontiformes , Daphnia , Dietilestilbestrol/toxicidad , Ecología , Exposición a Riesgos Ambientales , Heces/análisis , Ratones , Fenotiazinas/toxicidad , Caracoles , Sulfametazina/toxicidadRESUMEN
Broiler chickens were fed on a commercial diet containing 0.0125% clopidol for 34 days. They were killed 0-10 days after withdrawal of the premedicated feed and clopidol was determined in liver and muscle samples by a sensitive gas-liquid chromatography (g.l.c.) method. During the first two post-withdrawal days the clopidol concentration in the liver decreased rapidly from 7 to 0.5 mg/kg and the level in muscle declined from 3 to 0.1 mg/kg. There was little decline in the clopidol concentrations from days 2 to 10, the levels during this period being 0.2-0.8 mg/kg in liver and 0.05-0.2 mg/kg in muscle. In addition to the above experimental study, liver and muscle samples collected at a Swedish slaughterhouse from broiler chickens raised on clopidol-containing feed were analysed for residues of this drug. Large variations were found in the clopidol levels in broilers from different producers. The levels in the liver ranged from 0.05 to 8.0 mg/kg and those in muscle from 0.03 to 3.5 mg/kg. The present results emphasize the need to carry out field studies to check the levels of feed additive residues in edible tissues from chickens.