Determination of exposure to major iodide ion uptake inhibitors through drinking waters

Abstract

Goiter, abnormal enlargement of the thyroid gland, is a significant worldwide public health problem. Iodine deficiency is known as the most common cause. Iodine is actively transported as iodide ion (I-) using Sodium Iodide Symporter (NIS) and sufficient blocking of I- transportation prevents the synthesis of thyroid hormones. The transportation can be blocked by some polyatomic anions known as I- uptake inhibitors. Perchlorate (ClO4-), thiocyanate (SCN-) and nitrate (NO3-) are reported as the major I- uptake inhibitors and exposure could be through various routes. Drinking water is an important exposure route. Since water is essential to sustain life, drinking water safety is very important for the protection of public health. However, as a result of natural and human-based processes, water can be contaminated and contamination of drinking water is a global food safety problem due to causing significant health and environmental problemsIn that context, this study aims to determine exposure levels to I- uptake inhibitors that arise from drinking waters at five different districts in Antalya, Turkey. Collected water samples contained NO3- and ClO4- in the range of 0.86-47.42 mg/L and <LOQ-0.11 mg/L, respectively. SCN- levels were <LOQ in all samples. Daily exposure was calculated for different age groups of 2-65+ years using contaminant levels, water consumption and body weight data. Mean NO3- and ClO4- exposure levels were in the range of 115.89-375.06 and 0.07-0.22 mu g/kg bw/d, respectively. Exposure levels were decreased with increasing age and the highest exposure levels were calculated for children due to their lower body weight. Although no risk was determined for the I- uptake inhibitors in tested locations based on the guideline values recommended by EPA and WHO, there has been a need for more exposure assessment studies in the areas where the high prevalence of goiter is observed all over the world.