Analysis on the survey results of iodine content in drinking water in Chongqing, 2017

Abstract

Objective To understand the distribution of iodine content in drinking water of residents in Chongqing. Methods In 2017, according to the Technical Plan for the Investigation of Iodine Content of Drinking Water in surveys on water iodine content, water source type, well depth and geographical situation were carried out in 38 districts (counties) and Wansheng Economic and Technological Development Zone in Chongqing, with township (town, street office) as a survey unit. Among them, the township (town, street office) with the median of water iodine > 10 μg/L was investigated with a administrative village (residential committee) as a survey unit. The Method for Iodine Detection in Iodine-deficient and High-iodine Areas recommended by the National Iodine Deficiency Disease Reference Laboratory was adopted for water iodine detection. The water iodine contents of different water source types, different well depths and different areas were compared and analyzed. Results In 2017, a total of 17 584 water samples were collected in Chongqing. The median of water iodine was 1.7 μg/L, ranging from 0.2 to 124.0 μg/L, with the content 100 μg/L accounted for 0.01% (2/17 584). Among the 1 023 townships (towns, street offices), 1 020 townships (towns, street offices) were water iodine < 10 μg/L, and 3 townships (towns, street offices) were water iodine in 10-100 μg/L, they were Anfu Street (25.8 μg/L), Qingsheng Town (11.8 μg/L) and Longji Town (31.0 μg/L) of Rongchang District. The differences of iodine content between deep well water, tap water andshallow well water (4.2, 1.5, 1.2 μg/L) were statistically significant (H=2 008.4, P < 0.01). There was a positive correlation between well depth and water iodine (r=0.298, P < 0.01). The medians of water iodine in main, northeast, southeast, and western areas were 1.8, 0.8, 1.1 and 3.7 μg/L, respectively, and the differences of water iodine content between different regions were statistically significant (H=4 080.5, P < 0.01). The water iodine contents of northeast and southeast areas (both were mountainous areas) were relatively low. Conclusions Chongqing is an iodine deficiency area. In most areas, the iodine content of drinking water is low, and the risk of iodine deficiency in mountainous areas is greater than that in other areas. Key words: Drinking water; Iodine; Deficiency diseases