An investigation of iodine nutritional status in water-borne high iodine areas in Shandong Province, 2017.

Objective To observe the iodine nutritional status in historical water-borne high iodine areas in Shandong Province, so as to provide a basis for improving the intervention strategy of high-iodinated goiter in water-borne high iodine areas. Methods In 2017, in 38 historical high-iodine counties (cities, districts) in 7 cities of Shandong Province, each county (city, district) was divided 5 regions according to the east, west, south, north, and middle. One township (street) was taken in each regions, and four administrative villages were selected in each township (street). In each administrative village 15 household salt samples were extracted for non-iodine salt detection; detection of iodine content of drinking water, urine iodine content and thyroid volume of children aged 8 - 12 years were carried out in 19 high iodine counties (cities, districts). The semi-quantitative method was used to detect the iodine level of edible salt of residents; the arsenic cerium catalytic spectrophotometry method(WS/T 107-2006) was used to detect the water iodine and urinary iodine content; the B-ultrasound method was used to examine the thyroid volume of children. Results A total of 9 703 edible salt samples were collected from residents, including 9 575 non-iodine salt and the consumption rate of non-iodine salt was 98.68%. Among the 38 high iodine counties (cities, districts), 20 counties (cities, districts) all stopped supplying iodized salt and 18 counties(cities, districts) partial stopped, the consumption rates of non-iodine salt were 99.37% (6 013/6 051) and 98.54% (3 562/3 652), respectively. The iodine content of drinking water in 19 monitoring sites was detected. The median water iodine was 75.50 μg/L, ranging from 8.50 to 420.70 μg/L. Among them, the median water iodine of 9 monitoring sites was > 100 μg/L, still belonged to the water-borne high iodine area. Totally 2 009 children were detected urinary iodine, the median urinary iodine concentration was 256.35 μg/L; the goiter rate of children aged 8 - 12 years was 7.86% (158/2 009), there was a statistically significant difference in the rate of goiter between children of different ages (χ2 = 43.649, P < 0.05). Conclusions Although the consumption rates of non-iodine salt in historical water-borne high iodine areas of Shandong Province are at a higher level, the water iodine content of drinking water has a larger span, iodine nutrition in children is over the appropriate level. The coverage of projects to improve water quality and reduce iodine in high iodine areas should be further expanded, and monitoring of iodine nutritional status of key populations should be strengthened. Key words: Iodine; Salts; Drinking water; Urine; Goiter