Fluoride Action Network


212 Wistar rats were divided randomly into five groups, each of which was fed on one of the following regimes: (1) Normal iodine and fluorine; (2) normal iodine, 10 ppm fluorine; (3) normal iodine, 30 ppm fluorine; (4) now iodine, normal fluorine; (5) low iodine, 10 ppm fluorine. The experiment lasted seven months. The results showed that severe morphologic and functional damage of the· thyroid appeared in the rats drinking water containing 30 ppm fluonne, but only slight abnormal ultrastructural changes of’ thyroid cells appeared in rats drinking water containing 10 ppm fluorine; rats with iodine deficiency showed proliferative changes of the thyroid; rats on iodine deficient diet and drinking water containing 10 ppm fluorine showed morphologic and functional damage as well as proliferation. The study suggests that there is synergistic action of iodine deficiency and fluorine intoxication on the thyroid.