Survey of iodized salt coverage in areas with different water iodine concentrations and the iodine status of local women.

Abstract

There were only two definitions of iodine-deficient (water iodine concentration < 10μg/L) and iodine-excess areas (water iodine concentration > 100μg/L) in China before 2020. Areas with water iodine concentration between 10 and 100μg/L implement the same policy as iodine-deficient areas to provide iodized salt. The definition of iodine-adequate areas was formulated in 2020 for the first time. The paper aims to investigate the coverage rate of iodized salt (CR) in different areas defined according to the latest national standards, evaluate the iodine status of local women, and provide a basis for the revision and improvement of relevant policies. A total of 1948 women aged 18-60 were recruited from the iodine extra-high areas (IEHA), iodine-excess areas (IEA), iodine-adequate areas (IAA), inland iodine-deficient areas (IIDA), and coastal iodine-deficient areas (CIDA). Information on daily diet was collected with the Food Frequency Questionnaire. Drinking water, salt, food, and urine samples were collected and tested in our laboratory. Based on the recommended daily iodine intake, we assessed whether the subjects' daily iodine intake levels were adequate. The CR and the median urinary iodine concentrations (UICs) were 4.02% and 98.03μg/L in CIDA, 89.74% and 144.93μg/L in IIDA, 26.55% and 178.60μg/L in IAA, 8.78% and 446.5μg/L in IEA, 3.95% and 605.4μg/L in IEHA, respectively. The differences among these five areas were statistically significant (P < 0.0001). The daily dietary iodine intakes were mainly from drinking water in IAA (63.92%), IEA (92.29%), and IEHA (92.93%), and were mainly from iodized salt in IIDA (59.22%) and food in CIDA (86.6%). Women in IAA and IIDA were in an adequate iodine state. Women in IEA and IEHA were in an iodine-excess state, and it is necessary to carry out water improvements projects. Women in CIDA were in a slight iodine-deficient state, and health education on scientific iodine fortification should be strengthened to increase iodine intake.