RESUMO
Objective:To dynamically observe the changes in iodine level in residents' drinking water after the change of regional water supply mode (2020) in Jiangsu Province.Methods:The survey of water iodine level was conducted from June to October 2020 in administrative villages of Jiangsu Province with a median water iodine ≥40 μg/L in 2017. The survey mainly covered 1 537 administrative villages in 21 counties (cities and districts) of 5 cities, including Huaian City, Lianyungang City, Suqian City, Yancheng City, and Xuzhou City. Based on the standard of "Definition and Demarcation of Iodine Deficient Areas and Iodine Adequate Areas" (WS/T 669-2020), the administrative villages with a median water iodine of 40 - 100 μg/L were classified as iodine adequate areas. Water iodine testing was conducted using the "Method for Water Iodine Testing in Iodine Deficient and High Iodine Areas" recommended by the National Reference Laboratory for Iodine Deficiency Disorders.Results:Totally 1 498 administrative villages in Jiangsu Province were monitored in 2020, all of which had centralized water supply. The minimum value of water iodine in all administrative villages was 1.2 μg/L and the maximum value was 606.7 μg/L, and the median water iodine was 35.2 μg/L. Among them, 206 administrative villages had median water iodine < 10 μg/L, accounting for 13.75% (206/1 498); 610 administrative villages had median water iodine from 10 to < 40 μg/L, accounting for 40.72% (610/1 498); 635 administrative villages had median water iodine from 40 to 100 μg/L, accounting for 42.39% (635/1 498); and 47 administrative villages with median water iodine > 100 μg/L, accounting for 3.14% (47/1 498). Except for Sucheng District in Suqian City, Xinyi City and Gulou District in Xuzhou City, Qingjiangpu District and Xuyi County in Huaian City, and Guannan County in Lianyungang City, the median water iodine in the administrative villages of the remaining 15 counties (cities and districts) in 2020 decreased significantly compared to 2017, and the differences were statistically significant ( P < 0.05). Conclusion:After change of regional water supply mode in 2020, in most monitored counties (cities and districts) of Jiangsu Province, the water iodine level of administrative villages has decreased significantly compared to 2017.