Examining the Influence of Desalinated Water on Iodine Concentration in Tap Water in Israel

Abstract Introduction: In Israel, desalinated water is a major source of drinking water. Previous studies have suggested that the levels of iodine in water provided by authorities may not accurately reflect the levels reaching end-users. Materials and Methods. We analyzed 21 tap water samples collected from different localities across Israel, 13 post-treated desalinated water samples from three of the largest Israeli desalination plants, and several natural water samples. An improved method of ICP-MS developed in our laboratory was used to analyze the content of iodine and other macro-elements, and determination of iodine was performed in alkaline media. Results: Our results showed that it is possible to distinguish between sample groups based on iodine concentration, water hardness, and Ca/Mg ratio. The median iodine concentrations for four groups of tap water samples ranged from 0.3 to 12.3 µg/L, which is lower than the concentrations previously reported by other researchers in Israel. Based on typical consumption, the water samples can provide no more than 3.39% of the recommended dietary allowance level for iodine. The analysis of post-treated desalinated water samples indicated that these waters comply with industrial specifications but contain only trace concentrations of iodine and much less magnesium than recommended by different public health authorities for public consumption of drinking water. Conclusion: The total iodine concentrations found were lower than several observations reported in previous years in the literature. There are currently no strict regulations regarding iodine and magnesium levels in drinking and/or softened (desalinated) water, but the intensive desalination plant application is already exhibiting a negative impact on public health. Further investigations are needed, but the present study provides useful insights for developing an effective policy to ensure adequate iodine supply for the population of Israel through drinking water.