CONSUMPTION OF DRINKING-WATER WITH HIGH NITRATE LEVELS CAUSES HYPERTROPHY OF THE THYROID

We studied the effect of nitrate contamination of drinking water on vo lume and function of the thyroid in human populations exposed to diffe rent nitrate levels in their drinking water. Two sets of low and mediu m (tap) water, respectively medium and high (well) water nitrate expos ure groups were compared. Drinking of nitrate-contaminated water was d ose-dependently related with 24-h urinary nitrate excretion and saliva ry nitrate levels. No iodine deficiency was observed in any of the nit rate exposure groups. A dose-dependent difference in the volume of the thyroid was observed between low and medium vs. high nitrate exposure groups, showing development of hypertrophy at nitrate levels exceedin g 50 mg/l. An inverse relationship was established between the volume of the thyroid and serum thyroid stimulating hormone (TSH) levels.