Introduction: An increase in thyroid diseases after the Chernobyl, mostly due to radioactive iodine, has been scientifically recognized. It is also known the effect of nitrate on iodine metabolism: being a competitive inhibitor of sodium-iodine symporter nitrate prevents iodide uptake by the thyroid and compromises thyroid hormone synthesis.
The aim of the study was to investigate the incidence of thyroid and salivary glands abnormalities by ultrasound (US) screening according to drinking water nitrate concentration.
Methods: Thyroid and salivary glands US with the volume estimation was performed in 264 Belarusian subjects living in the areas of Brest region polluted by radionuclides after the Chernobyl accident. The participants average age was 21.0±4.5 yr. The urine iodine concentrations and nitrate drinking water levels were measured.
Results: Median urinary iodine varied from 160 to 175 μg/l indicating no iodine deficiency. According to nitrate concentration (Median) in drinking water, the examined subjects were divided in three groups: 1 Stolin-city (20 mg/l), 2 Olmany village (334 mg/l), 3 Olshany village (880 mg/l). Thyroid hyperplasia was detected in 3,8% of 157 subjects in the group 1; in 11,4% in the group 2 (out of 79 persons) and in 17.9% in the group 3 (out of 28 persons) (P<0.05). The salivary gland ultrasonic abnormalities were found more frequently in people in Olshany village (abnormal echogenicity with hyperechoic threads in 53.6% of cases vs 17.7% in the group 2 and 22.3% in the group 1, (P<0.01).
Conclusion: The villages Olmany and Olshany of Brest region may be considered the areas with high nitrate drinking water levels, according to WHO criteria. Unfavorable ecological conditions such as high drinking water nitrate levels may contribute to the thyroid and salivary glands abnormalities development and potentiate relative iodine deficiency even in the areas with normal iodine supply.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector