Fluoride Action Network


Thirty-two one-month-old Wistar albino rats were divided randomly into four equal groups of eight (female:male = 3:1). To assess damage to DNA in their brain cells, the first group (1) of rats served as the untreated control, the second group (2) was administered high fluoride (HiF, 100 mg NaF/L in the drinking water), the third group (3) was placed on a low iodine intake (LI, 0.0855 mg I/kg diet), and the fourth group (4) was exposed to the same high fluoride and low iodine combined (HiF+LI). At 20 months of age, the rats were anesthetized and their brain cells prepared for single cell gel electrophoresis (SCGE = comet assay). DNA damage in the brain cells assessed by the tailing ratio percent was 24.68±20.81% in the control group 1 and in the HiF, LI, and HiF+LI groups 2, 3, and 4, it was 90.93±9.17%, 89.04±4.99%, and 92.48±4.04%, respectively. Moreover,the proportion of grade III damage to the brain cells increased by 24.00% in the HiF group 2, 21.88% in the LI group 3, and 33.33% in the HiF+LI group 4, but only by 8.0% in the control group 1. These results indicate that DNA strands in the brain cells of rats are adversely affected by exposure to high fluoride, low iodine, and together in combination.