To learn about the evaluation of the effectiveness of prevention and control measures in water-borne high iodine areas in Shanxi Province, and provide basis and suggestions for development of water-borne high iodine hazard control standards.

A cross-sectional survey was conducted in 44 high iodine administrative villages planned for water improvement in 2019 in Shanxi Province, from March to June 2019 (before water improvement) and from March to June 2020 (after water improvement), respectively. Drinking water samples from residents in survey villages, as well as salt at home and urine samples from children aged 6 - 12 were collected for iodine level determination, and thyroid volume of the children was examined. Based on the water iodine level before water improvement, at group spacing of 100 μg/L, the coverage rate of non-iodized salt in each water iodine level group, as well as the urinary iodine and goiter rate in children, were compared.

Before water improvement, the median water iodine of the 44 surveyed villages was 260.6 μg/L, water iodine all > 100 μg/L. After water improvement, the median water iodine was 50.3 μg/L, water iodine in 32 villages ≤100 μg/L, and 12 villages > 100 μg/L. The coverage rate of non-iodized salt increased from 50.0% (806/1 612) before water improvement to 61.8% (922/1 492) after water improvement, with a statistically significant difference (χ² = 65.10, P < 0.001). All of the coverage rates of non-iodized salt in each water iodine group were less than 90%. The median urinary iodine of children decreased from 448.9 μg/L before water improvement to 382.5 μg/L after water improvement, the difference was statistically significant (Z = 20.50, P < 0.001). The median urinary iodine in each group was still ≥300 μg/L. Among which there was statistically significant difference in median urinary iodine in groups > 100 - 200 and > 400 - 500 μg/L before and after water improvement (Z = 8.11, - 9.25, P = 0.005, 0.003). The overall goiter rate of children decreased from 7.8% (126/1 612) before water improvement to 4.3% (64/ 1 492) after water improvement, with a statistically significant difference (χ² = 16.77, P < 0.001). After water improvement, the goiter rates of children in water iodine ≤100 μg/L was 3.7% (41/1 117) and > 100 μg/L was 6.1% (23/375), respectively, with a statistically significant difference (χ² = 4.15, P = 0.042).

The prevention and control effect is good in water-borne high iodine areas in Shanxi Province, the water iodine and goiter rate in children are significantly reduced. However, the coverage rate of non-iodized salt is still relatively low, and excessive iodine nutrition. It is recommended to use the iodine level in drinking water, median urinary iodine in children, and goiter rate as technical indicators to develop national standards for controlling the hazards of high iodine in water sources.

Drinking water; Iodine; Excess; Prevention and control; Effect