The Effects of Chlorine Intake on Some Morphometric Parameters of the Thyroid Gland in Lambs

Abstract

KóÀová M., E. Békeová, M. Levkut: The Effects of Chlorine Intake on Some Morphometric Parameters of the Thyroid Gland in Lambs. Acta Vet. Brno 1999, 68: 191-195.The aim of the study was to determine whether drinking water containing two concentrations of chlorine (0.3 mg . l -1 or 1.8 mg . l -1 ) affects morphometric indicators of follicular epithelial cells and the diameter of thyroid gland follicles in young lambs.The height of follicular epithelial cells, the diameter of thyroid gland follicles, the frequency of epithelial cell height categories, and the frequency of follicular diameter categories were studied in two groups of lambs after two treatments: one for four weeks and the other for three months. The first group had access to drinking water with 0.3 mg . l -1 chlorine (short-term intake and low Cl concentration) for four weeks. The second group had access to drinking water containing 1.8 mg . l -1 chlorine (long-term intake and high concentration) for three months.A significant increase (P < 0.01) in follicular epithelial cell height and a significant frequency distribution shift to the higher cellular height categories was observed after intake of chlorinated water (0.3 mg . l -1 ), (P < 0.01 for cell height categories 3.1-4 and 4.1-5 µm) for four weeks. There was also a significant shift (P < 0.01 for cell height categories 4.1-5 and 5.1-6 µm) in lambs receiving 1.8 mg . l -1 chlorine in their drinking water for three months as compared to controls.The diameter of thyroid gland follicles significantly decreased (P < 0.01), and the percent of small thyroid follicles significantly increased (for diameter categories 20.1-40 and 40.1-60 µm P < 0.01 and P < 0.05, respectively) in lambs receiving 1.8 mg . l -1 chlorine in drinking water for three months as compared to controls.Our morphometric findings suggest that chlorine interferes with the thyroid metabolism in lambs, however, with no macroscopically detectable changes of the thyroid.