versão impressa ISSN 1405-3195
OCAMPO-CAMBEROS, Luís; ROSILES-MARTINEZ, Rene; TAPIA-PEREZ, Graciela e SUMANO- LOPEZ, Héctor. Elimination kinetics of lindane at three doses in a cow's milk fat. Agrociencia [online]. 2010, vol.44, n.4, pp. 461-469. ISSN 1405-3195.
There is evidence of lindane being eliminated through milk, and the risk of exposure by daily consumption is much greater than in other types of food; therefore, knowing and respecting the time of withdrawal of any product consumed by the human being is fundamental. The present study was carried out with the purpose to assess if lindane application using spray at 75 and 300 μg kg-1 body weight (recommended dose and overdose) generated lower lindane concentrations in milk than the permissible maximum limit (0.01 mg kg-1). Therefore, the lindane concentrations in milk of Holstein-Friesian cows were determined by gas chromatography with electron capture detector after a topical treatment by spraying a dose of 75 (group A) and 300 μg kg-1 (group B), and without lindane (group C). The elimination variables in milk were: elimination coefficient (Kel), mean lifetime (T½β) and withdrawal time. Eight cows with mean weight of 525±12.5 kg producing 19 -23 L d-1 were utilized. Skimming milk, samples of 75 mL per quarter of the morning milking were obtained in order to make one single sample per milking for 14 d, freezing it at - 20 °C until its analysis. Using the analytical method, a recovery of 90.37±1.52 % (R2=0.986) was achieved. The minimum detectable quantity was 0.001 mg L-1 (and the minimum quantifiable amount 0.008 mg L-1). For group A, 0.382 h-1 Kel and T½β = 1.81 d were obtained, and the time required to reach from the quantity of the least residues to the maximum residue limit (MRL) by WHO/FAO of 0.01 mg kg-1, was 13 d. For group B, Kel = 0.243 h-1 and T½β = 2.84 d were obtained, and the time the quantity of lowest residues needed to reach the maximum residue limit (MRL) was 29 d. The implemented method was validated; lindane concentrations in milk may be higher than the MRL value and seem to show accumulative kinetics of the zero order and dependent on the dose, which may negatively impact public health, especially because the detected concentrations were higher than the maximum permissible ones by OMS.
Palavras-chave : kinetics; gas chromatography; milk; lindane; cows.