Determination of nis i̇nhibitor perchlorate levels in water samples taken from different cities

Perchlorate is a mobile and stable inorganic ion. Perchlorate inhibits iodide transport to the thyroid by sodium-iodide symporter (NIS) because of its similar chemical properties to iodide. Thyroid dysfunction can be observed in sensitive populations (pregnant woman, infants, children) during iodide deficiency. Previous study with 24-hour urine samples from Istanbul, Ankara and Isparta showed that volunteers have been exposed to perchlorate. 145 random tap water samples representing entire cities, have been collected from Ankara, Isparta, Istanbul, Kayseri and Sakarya to determine perchlorate concentrations. HPLC-MS/MS method was used for perchlorate analysis. Detection and quantification limits were calculated as 0.008 µg/L and 0.026 µg/L, respectively. Inter-assay variation for 0.4 and 2 µg/L control samples was calculated as %6.72 and %2.72, respectively. Perchlorate concentrations in all samples were between <0.02 - 3.75 µg/L. Mean value for all samples were 0.17 µg/L. Median values for Istanbul, Ankara, Sakarya, Isparta and Kayseri were 0.081, 0.081, 0.041, 0.029 ve 0.27 µg/L, respectively. Highest perchlorate concentration was observed in a sample taken from Ankara. Highest median value were found in Kayseri samples with 0.27 µg/L and %75 percentile was 0.34 µg/L. Perchlorate concentrations in water samples were lower than the interim drinking water health advisory level (15 µg/L) determined by EPA. In conclusion, our results showed that perchlorate in drinking water is not the main source of exposure in these cities. Therefore, food products may be the main source of this exposure and studies have to be directed to determining levels of perchlorate in food products.