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This project describes the external exposure levels of metalworking fluid (MWF) in an automobile parts manufacturing factory and analyzes the health effects of MWF on workers so as to provide a scientific basis for optimizing the MWF testing process and evaluating occupational hazards. MWF in the air of the workplace was collected according to the National Institute for Occupational Safety and Health' analysis method (NIOSH 5524). The mass concentrations of MWF total aerosols and extracted aerosols were determined by weighing and binary or ternary solvent extraction. The quantitative relationship between them was analyzed. The propensity score matching (PSM) method was used to establish the group of subjects. Demographic information, allergic diseases, and clinical laboratory indicators were collected through questionnaire and health examination data, and the health effects of MWF were assessed. Personal sampling of 38 workers in three posts was carried out using a polytetrafluoroethylene (PTFE) filter. The arithmetic means of concentration of total aerosols was 0.43(0.13–1.02) mg/m3, and the extractable aerosols concentration was 0.23(0.05–0.55) mg/m3. There was a significant correlation between total and extractable aerosol levels, and a linear regression equation was established: Y = 0.469X + 0.024 (X is the total aerosols concentration, Y is the extracted aerosols concentration). There was no significant difference in blood routine, liver function, or other biochemical results or indicators between the exposed workers and controls (P > 0.05). The clear linear relationship between concentrations of aerosols indicates that the extracted aerosols level can be reasonably inferred from the total aerosols. Under the circumstances investigated in this project, MWF exposure did not induce significant adverse health effects, as evidenced by the results of occupational medical examination. [ABSTRACT FROM AUTHOR]

Objective: To estimate the contribution of direct-drinking water provided in school to dietary intake (DI) and recommended nutrient intake (RNI) of calcium and magnesium, and to explore its influence on the height in school-age children., Methods: Tap water and direct-drinking water samples were collected from schools in Taicang City to test the contents of calcium and magnesium, and compared by one-way ANOVA and post-hoc test. Contribution rates of direct-drinking water to DI and RNI were calculated by using the contents of calcium and magnesium and data from the Nutrition and Health Status Survey 2021 . A retrospective cohort was conducted among 4,850 first-grade children consuming direct-drinking water in Taicang City from 24 primary schools in 2019. Group 1 (1,070 boys and 946 girls) consumed UF-process water with normal calcium and magnesium contents and Group 2 (1,548 boys and 1,286 girls) consumed NF/RO-process water with very low calcium and magnesium contents. During 2019-2023, the height and height growth were analyzed with the Student's t -test., Results: The highest calcium content was examined in tap water samples, followed by direct-drinking water samples supplied through a UF, NF, and RO system ( F  = 1,227.725, p  < 0.001). The highest magnesium content was examined in water supplied through a UF system, followed by that through a tap, NF and RO system ( F  = 146.504, p  < 0.001). Calcium and magnesium contents in direct-drinking water supplied through a UF system changed little compared with those in tap water, which were significantly reduced in direct-drinking water supplied through a NF and RO system. The contribution rates of direct-drinking water to DI of calcium and magnesium were 8.95 and 2.78%, respectively, and those to RNI of calcium and magnesium were 2.63 and 1.96%, respectively. There were no significant differences in the height and height growth of first-grade children drinking water supplied through the UF system vs. NF/RO system ( p  > 0.05)., Conclusion: Direct-drinking water processed through a NF or RO system should be cautiously adopted in primary and secondary schools. A UF system is preferred in schools where no health concerns are associated with water quality., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Gu, Gong, Li, Zhang, Wu, Wang, Ni, Zhang and Jiang.)