Objective:To investigate the distribution of iodine in drinking water in external environment and the iodine nutrition status of key population in Guizhou Province, and to provide a basis for further precise implementation of prevention and control strategy of "adapting to local conditions, providing classified guidance, and scientifically supplementing iodine".Methods:From April to September 2023, a survey on the iodine level of residents' drinking water was conducted in administrative villages (neighborhood committees, hereafter referred to as administrative village) in 88 counties (districts) of 9 cities (prefectures) in Guizhou Province. At the same time, one township (town) was selected from each of the five districts of east, west, south, north and center of each county (district). From each township (town), 40 non-boarding students aged 8 - 10 years old from one primary school and 20 pregnant women were selected. Household edible salt sample and once random urine sample were collected for detection of salt iodine and urinary iodine levels.Results:The survey covered 16 492 administrative villages in 1 481 townships (towns), 88 counties (districts), 9 cities (prefectures) throughout the province. A total of 51 531 samples of residents' drinking water were collected, with a median water iodine level of 1.50 μg/L and a range of 0.01 - 98.70 μg/L. Among them, there were 16 284, 208, and 0 administrative villages with median water iodine levels < 10, 10 - < 40, and 40 - 100 μg/L, respectively, accounting for 98.74%, 1.26%, and 0, respectively. A total of 26 491 samples of household edible salt were collected from children and pregnant women, with a median salt iodine levels of 27.6 mg/kg. The coverage rate of iodized salt was 99.6% (26 395/26 491), and the qualified iodized salt consumption rate was 97.0% (25 708/26 491). And 17 657 urine samples from children and 8 834 urine samples from pregnant women were collected, with median urinary iodine levels of 222.1 and 164.4 μg/L, respectively. There were statistically significant differences in urinary iodine levels among children of different genders and ages ( Z = - 6.08, H = 19.17, P < 0.001). The results of correlation analysis showed that there was no correlation between urinary iodine of children and pregnant women and water iodine ( r = 0.01 0.02, P > 0.05), while urinary iodine of pregnant women was positively correlated with salt iodine ( r = 0.02, P = 0.041). Conclusions:The external environment of Guizhou Province is generally deficient in iodine. Under the universal salt iodization policy, children have sufficient iodine nutrition, and pregnant women have an appropriate level of iodine nutrition. Comprehensive prevention and control measures, mainly based on universal salt iodization, should be continuously carried out to eliminate the harm of iodine deficiency.

Objective:To investigate the distribution of iodine in drinking water in external environment and the iodine nutrition status of key population in Guizhou Province, and to provide a basis for further precise implementation of prevention and control strategy of "adapting to local conditions, providing classified guidance, and scientifically supplementing iodine".Methods:From April to September 2023, a survey on the iodine level of residents' drinking water was conducted in administrative villages (neighborhood committees, hereafter referred to as administrative village) in 88 counties (districts) of 9 cities (prefectures) in Guizhou Province. At the same time, one township (town) was selected from each of the five districts of east, west, south, north and center of each county (district). From each township (town), 40 non-boarding students aged 8 - 10 years old from one primary school and 20 pregnant women were selected. Household edible salt sample and once random urine sample were collected for detection of salt iodine and urinary iodine levels.Results:The survey covered 16 492 administrative villages in 1 481 townships (towns), 88 counties (districts), 9 cities (prefectures) throughout the province. A total of 51 531 samples of residents' drinking water were collected, with a median water iodine level of 1.50 μg/L and a range of 0.01 - 98.70 μg/L. Among them, there were 16 284, 208, and 0 administrative villages with median water iodine levels < 10, 10 - < 40, and 40 - 100 μg/L, respectively, accounting for 98.74%, 1.26%, and 0, respectively. A total of 26 491 samples of household edible salt were collected from children and pregnant women, with a median salt iodine levels of 27.6 mg/kg. The coverage rate of iodized salt was 99.6% (26 395/26 491), and the qualified iodized salt consumption rate was 97.0% (25 708/26 491). And 17 657 urine samples from children and 8 834 urine samples from pregnant women were collected, with median urinary iodine levels of 222.1 and 164.4 μg/L, respectively. There were statistically significant differences in urinary iodine levels among children of different genders and ages ( Z = - 6.08, H = 19.17, P < 0.001). The results of correlation analysis showed that there was no correlation between urinary iodine of children and pregnant women and water iodine ( r = 0.01 0.02, P > 0.05), while urinary iodine of pregnant women was positively correlated with salt iodine ( r = 0.02, P = 0.041). Conclusions:The external environment of Guizhou Province is generally deficient in iodine. Under the universal salt iodization policy, children have sufficient iodine nutrition, and pregnant women have an appropriate level of iodine nutrition. Comprehensive prevention and control measures, mainly based on universal salt iodization, should be continuously carried out to eliminate the harm of iodine deficiency.

The current problems with corneal transplant,including shortage of donors and immune rejection,could be effectively solved by constructing cornea in vitro with tissue engineering techniques,in which the selection of suitable scaffold materials is especially critical.Chitosan and its derivatives are natural biomaterials with excellent biocompatibility,biodegradability,mechanical property and plasticity,indicating wide application prospects in corneal tissue engineering.This article systematically reviews the research advances in chitosan and its derivatives in corneal tissue engineering,and the existing problems are also highlighted in order to provide theoretical basis for further clinical research.