Relationships between screen viewing and sleep quality for infants and toddlers in China: A cross-sectional study.

Aim: Currently young children have more opportunity to access all kinds of media, while their sleep duration has been steadily decreasing. However, little is known about the relationships between screen viewing and sleep quality, and the reasons of screen viewing for children under three years old in China. This study aimed to describe the relationships between screen viewing and sleep quality of infants and toddlers in mainland China. Methods: A cross-sectional study was conducted. Eight hundred twenty-seven children were recruited at a health care unit from a university affiliated hospital in China, and the questionnaires were completed by their parents. An extended Brief Infant Sleep Questionnaire and a Screen Viewing Questionnaire were used to collect information on children's sleep quality and screen viewing. Multivariate linear regression models were used to assess the relationships between screen viewing and sleep quality among infants and toddlers, adjusted for sociodemographic variables. Results: Of the 827 children, 26.9% of the infants and 61.4% of the toddlers did not comply with the World Health Organization (WHO) guideline on screen time. Even after adjusting for the sociodemographic covariates for both infants and toddlers, negative relationships between screen time and total sleep time (P < 0.001), and screen time and nighttime sleep (P < 0.001) existed. TV viewing time was negatively related to infants' total sleep time (ß = -0.15, P < 0.001) and toddlers' nighttime sleep (ß = -0.1, P < 0.05). Smartphone viewing time was negatively related to toddlers' total sleep time (ß = -0.12, P < 0.05) and daytime sleep (ß = -0.22, P < 0.05). Parents who offered screen media for children when they needed to do house chores were more likely to report that their children had less total sleep time (ß = -0.1, P < 0.05) and shorter longest sleep episode (ß = -0.1, P < 0.05). Conclusion: The majority of toddlers did not meet the WHO guidelines on screen time in China. Screen time was negatively related to total sleep time and nighttime sleep among infants and toddlers. Practical strategies, such as education programs on children's screen viewing, more outdoor exercises and indoor parent-child activities, providing other educational materials instead of screening, early sleep, restricted use of TVs and smartphones, and screen co-viewing, are needed to improve young children's sleep quality and promote their development.

Safe utilization and zoning on natural selenium-rich land resources: a case study of the typical area in Enshi County, China.

Selenium (Se) is an essential trace element. However, Se in soil is often accompanied by heavy metals, such as cadmium (Cd), because of geological background. The safe utilization of such Se-rich land resources remains a challenge. A typical Se-rich area located in Enshi County, China, was systematically investigated with geochemical and epidemiological methods. The results show that Se in the topsoil is 0.84 ± 1.39 µg/g, whereas that of Cd is 0.93 ± 1.63 µg/g. And the concentration of Se and Cd in corn is 0.22 ± 0.96 µg/g and 0.15 ± 0.32 µg/g, respectively, which is mainly related to the high concentrations in soil. The benchmark dose limit of urinary Cd for ß2-microglobulin in subjects (n = 160) was calculated as 3.27 µg/g Cr. In view of crop-human dose effect and combining the relationship among the concentrations of crops and human biomarkers and the concentrations of crops and topsoil, this study established the models of land resource safety zoning. With that, the risk screening value of Cd in the soil could be obtained as 0.98 µg/g in this typical area. The proportions of priority utilization, safe utilization, and strict management of agricultural land area were 58.85%, 22.90%, and 18.25%, respectively, in Enshi, China. These results could provide scientific support for local agricultural development and ecological sustainability.

[Land Safety Zoning Method in High-Selenium and High-Cadmium Areas].

The selenium in the soil of Enshi, Hubei Province, is very rich, but there is also a certain degree of cadmium pollution risk. To scientifically utilize selenium-rich resources, a typical high-selenium and high-cadmium area in Shashi Township, Enshi City was selected as the research object. Combined with the corn cadmium selenium absorption model, a land safety zoning method was proposed. Comparing the health effects of selenium with the results of land safety zoning, it was found that the antagonism of selenium on cadmium can reduce the area of strict control of agricultural areas, and improve land use efficiency. Combined with the characteristics of cadmium and selenium in various crops in the study area, it is recommended for priority protection areas and safe-use areas to vigorously develop selenium-enriched agricultural products, and grow corn and tea in the structural adjustment area.