ACUTE 2,4-D POISONING IN TENCH (TINCA-TINCA L.) - LESIONS IN THE HEMATOPOIETIC PORTION OF THE KIDNEY

An experimental model was designed to study the acute lesions caused b y a continuous exposure to 2,4-dichlorophenoxyacetic acid (2,4-D) diss olved in water (400 mg/L) in hematopoietic kidney tissue in tench (Tin ca tinca L). Fifty fish were used in this study, 15 for calculating LC 50 and 35 were euthanized 1, 2, 5, 8, and 12 days postpoisoning (five treated and two controls each time). Tissue samples, fixed in 5% gluta raldehyde in 0.1 M phosphate buffer (pH 7.2) for histopathological exa mination, revealed marked alteration of hematopoietic tissue, characte rized by progressive swelling and cell necrosis, activation of the pha gocyte system, and subsequent formation of myelin figures. Variations recorded in hematocrit and hemoglobin levels in blood samples indicate d changes in membrane permeability, complementing the findings on hema topoietic tissue. The lethal dose (LC50) at 96 h demonstrated the impo rtance of the species and chemical form used as factors in calculating a product's toxicity.