Investigation of children's habits of smartphone usage and parental awareness of myopia control in underdeveloped areas of China.

AIM: To investigate the behaviors of smartphone usage and parental knowledge of vision health among primary students in the rural areas of China. METHODS: In this school-based, cross-sectional study, a total of 52 606 parents of students from 30 primary schools in the Xingguo County were investigated through an online questionnaire from July 2020 to August 2020. The self-designed questionnaire contained three parts: the demographic factors of both children and parents, parental knowledge and attitude toward myopia, and the preventive treatment of myopia. RESULTS: A total of 52 485 appropriately answered questionnaires were received, showing an effective response rate of 95.1%. The average age of the primary students was 10.1±0.98y and the prevalence of myopia among the primary students was 40.3%. The age of myopia occurrence in elementary students was significantly correlated with the parents' educational level (95%CI: 0.82-0.98, P=0.013), children's gender (95%CI: 1.08-1.20, P<0.001), school location (county or countryside) (95%CI: 0.59-0.66, P<0.001), children's smartphone ownership (95%CI: 1.09-1.26, P<0.001), and the average time spent on smartphone per day (95%CI: 0.78-0.88, P<0.001). School location in the county town, high family income, and high parents' educational level significantly affected both parents' myopia awareness and children's vision-threatening behaviors (P<0.01). Left-behind children showed a higher incidence of vision-threatening habits than those who lived with their parents (P<0.01). CONCLUSION: The results reveal the current situation of myopia development among rural primary school students and their parents. This survey will serve as a guidance for designing myopic prevention policies in the rural areas of China.

Acute and Subacute toxicity study of Olaquindox by feeding to common carp (Cyprinus carpio L.).

Olaquindox, is a growth-promoting feed additive for food-producing animals. As the banned medicinal feed additive, olaquindox in animal feed and water must be concerned as an important hazard index. To improve studies of the toxicity of olaquindox, we provide a toxicological effects of olaquindox on a common freshwater fish, Cyprinus carpio L. The results of acute toxicity tests showed that the 7d-LD50 of olaquindox administered by feeding for common carp was determined to be 3746.3 mg/kg. We also found that the accumulation coefficient of olaquindox in carp was 1.45-1.9. Based on the studied hematological and blood biochemical parameters (RBCs count, hemoglobin content, ALT, AST and SOD activity), we found that olaquindox induced significant alterations in all studied parameters. Regarding bioaccumulation, the results showed that olaquindox had more efficiency to internalize fish tissues (liver, kidneys and muscle). The histopathological investigation of tissues from poisoning fish revealed various alterations that varied between adaptation responses and permanent tissue damage. Our results indicate that olaquindox are toxic to common carp and have obvious accumulation, and all the data from acute and subacute toxicity experiments in common carp may provide a useful tool for assessing the toxicity of olaquindox to aquatic organisms.