Association between exposure to metalworking fluid aerosols, occupational noise and chronic kidney disease: a cross-sectional study in China.

BACKGROUND: Chronic kidney disease (CKD) carries a high public health burden yet little is known about the relationship between metalworking fluid (MWF) aerosols, occupational noise and CKD. We aimed to explore the relationship between occupational MWF aerosols, occupational noise and CKD. METHODS: A total of 2,738 machinists were sampled from three machining companies in Wuxi, China, in 2022. We used the National Institute for Occupational Safety and Health (NIOSH) method 5524 to collect individual samples for MWF aerosols exposure, and the Chinese national standard (GBZ/T 189.8-2007) method to test individual occupational noise exposure. The diagnostic criteria for CKD were urinary albumin/creatinine ratio (UACR) of ≥ 30 mg/g and reduced renal function (eGFR < 60 mL.min- 1. 1.73 m- 2) lasting longer than 3 months. Smooth curve fitting was conducted to analyze the associations of MWF aerosols and occupational noise with CKD. A segmented regression model was used to analyze the threshold effects. RESULTS: Workers exposed to MWF aerosols (odds ratio [OR] = 2.03, 95% confidence interval [CI]: 1.21-3.41) and occupational noise (OR = 1.77, 95%CI: 1.06-2.96) had higher prevalence of CKD than nonexposed workers. A nonlinear and positive association was found between increasing MWF aerosols and occupational noise dose and the risk of CKD. When daily cumulative exposure dose of MWF aerosols exceeded 8.03 mg/m3, the OR was 1.24 (95%CI: 1.03-1.58), and when occupational noise exceeded 87.22 dB(A), the OR was 1.16 (95%CI: 1.04-1.20). In the interactive analysis between MWF aerosols and occupational noise, the workers exposed to both MWF aerosols (cumulative exposure ≥ 8.03 mg/m3-day) and occupational noise (LEX,8 h ≥ 87.22 dB(A)) had an increased prevalence of CKD (OR = 2.71, 95%CI: 1.48-4.96). MWF aerosols and occupational noise had a positive interaction in prevalence of CKD. CONCLUSIONS: Occupational MWF aerosols and noise were positively and nonlinearly associated with CKD, and cumulative MWF aerosols and noise exposure showed a positive interaction with CKD. These findings emphasize the importance of assessing kidney function of workers exposed to MWF aerosols and occupational noise. Prospective and longitudinal cohort studies are necessary to elucidate the causality of these associations.

Shrub leaf area and leaf vein trait trade-offs in response to the light environment in a vegetation transitional zone.

The leaf is an important site for energy acquisition and material transformation in plants. Leaf functional traits and their trade-off mechanisms reflect the resource utilisation efficiency and habitat adaptation strategies of plants, and contribute to our understanding of the mechanism by which the distribution pattern of plant populations in arid and semi-arid areas influences the evolution of vegetation structure and function. We selected two natural environments, the tree-shrub community canopy area and the shrub-grass community open area in the transition zone between the Qinghai-Tibet Plateau and the Loess Plateau. We studied the trade-off relationships of leaf area with leaf midvein diameter and leaf vein density in Cotoneaster multiflorus using the standardised major axis (SMA) method. The results show that the growth pattern of C. multiflorus , which has small leaves of high density and extremely small vein diameters, in the open area. The water use efficiency and net photosynthetic rate of plants in the open area were significantly greater than those of plants growing in the canopy area. The adaptability of C. multiflorus to environments with high light and low soil water content reflects its spatial colonisation potential in arid and semiarid mountains.

Relationship between exposure to metalworking fluids and nonalcoholic fatty liver disease.

OBJECTIVE: The relationship between metalworking fluids (MWFs) and nonalcoholic fatty liver disease (NAFLD) has not been previously explored. We aim to investigate the relationship between occupational exposure to MWFs and the prevalence of NAFLD and to determine the cumulative exposure threshold per day. METHODS: In 2020, 2079 employees were selected randomly from one computer numerical control machining factory in Wuxi for a questionnaire survey, and occupational health examinations were conducted at the affiliated branch of Wuxi Eighth People's Hospital. MWF samples were collected within the factory using the National Institute for Occupational Safety and Health (NIOSH) 5524 method. NAFLD was defined as having a hepatic steatosis index (HSI) ≥ 36 without significant alcohol consumption. The relationship between NAFLD and MWFs was analyzed using logistic regression, and the daily exposure threshold was calculated using R software. RESULTS: MWF exposure was found to be a risk factor for NAFLD in exposed workers compared to the non-exposed group. The OR for NAFLD in workers exposed to MWFs compared to controls was 1.42 (95% CI: 1.04-1.95). An increased risk of NAFLD was shown to be associated with an increasing dose. The daily exposure dose threshold to MWFs was found to be 6.54 mg/m3 (OR = 2.09, 95% CI: 1.24-3.52). CONCLUSION: An association between occupational exposure to MWFs and NAFLD was found. As the concentration of exposure rose, the prevalence of NAFLD was also escalated.

Association between occupational noise and obesity: a retrospective cohort study in China.

OBJECTIVES: To determine the relationship between occupational noise, and obesity and body mass index (BMI) changes. METHODS: Baseline data were collected from participants (n = 1264) who were followed for 6 years in a retrospective study. The noise exposure level (LAeq,8h) was determined by equivalent continuous weighted sound pressure levels using the fixed-point surveillance method for noise monitoring. The cumulative noise exposure (CNE) level was determined using the equal energy formula, which is based on exposure history and level. RESULTS: The incidence of obesity at low (RR = 2.364, 95% CI 1.123-4.739]), medium (RR = 3.921, 95% CI 1.946-7.347]), high (RR = 5.242, 95% CI 2.642-9.208]), and severe noise levels (RR = 9.322, 95% CI 5.341-14.428]) was higher risk than the LAeq,8h control level. The risk of obesity among participants exposed to low (RR = 2.957, 95% CI 1.441-6.068]) and high cumulative noise levels (RR = 7.226, 95% CI 3.623-14.415]) was greater than the CNE control level. For every 1 dB(A) increase in LAeq,8h, the BMI increased by 0.063 kg/m2 (95% CI 0.055-0.071], SE = 0.004). For every 1 dB(A) increase in the CNE, the BMI increased by 0.102 kg/m2 (95% CI 0.090-0.113], SE = 0.006). CONCLUSIONS: Occupational noise is related to the incidence of obesity. The occupational noise level and occupational noise cumulative level were shown to be positively correlated with an increase in BMI.

A cohort study on the association between changing occupational stress, hair cortisol concentration, and hypertension.

OBJECTIVE: To explore the relationship between changing occupational stress levels, hair cortisol concentration (HCC), and hypertension. METHODS: Baseline blood pressure of 2520 workers was measured in 2015. The Occupational Stress Inventory-Revised Edition (OSI-R) was used to assess changes in occupational stress. Occupational stress and blood pressure were followed up annually from January 2016 to December 2017. The final cohort numbered 1784 workers. The mean age of the cohort was 37.77±7.53 years and the percentage male was 46.52%. At baseline, 423 eligible subjects were randomly selected for hair sample collection to determine cortisol levels. RESULTS: Increased occupational stress was a risk factor for hypertension [risk ratio (RR) = 4.200, 95% confidence interval (CI): 1.734-10.172]. The HCC of workers with elevated occupational stress was higher than that of workers with constant occupational stress [(ORQ score ≥70: geometric mean±geometric standard deviation = 5.25±3.59 ng/g hair; 60-90: 5.02±4.00; 40-59: 3.45±3.41; <40: 2.73±3.40) x2 = 5.261]. High HCC increased the risk of hypertension (RR = 5.270, 95% CI: 2.375-11.692) and high HCC was associated with higher rates of elevated diastolic and systolic blood pressure. The mediating effect of HCC was 0.51[(95% CI: 0.23-0.79, odds ratio(OR) = 1.67] and accounted for 36.83% of the total effect. CONCLUSIONS: Increased occupational stress could lead to an increase in hypertension incidence. High HCC could increase the risk of hypertension. HCC acts as a mediator between occupational stress and hypertension.

The Effect of Temperature and Sputtered Particles on the Wettability of Al/Al2O3.

Two kinds of Al2O3 ceramic samples with and without Al film deposited were designed respectively. The influences of temperature and high kinetic energy sputtering particles on the wettability and interface strength of Al/Al2O3 were studied by comparing the wetting behavior of molten aluminum on two samples. The results show that molten aluminum does not wet the Al2O3 sample without Al film deposited at 700 °C, the contact angle is 165°, and the interfacial shear strength is 28 MPa. With the increase of temperature, the contact angle decreases continuously, and the interface shear strength gradually increases. The fracture of the brazed joint is transferred from the interface to the brazing seam. In comparison, the sample deposited with Al film is wetted by molten aluminum at 700 °C, and the contact angle is only 12°. The interface shear strength is about 120 MPa and is less affected by temperature. The shear fracture of the joint occurs in the brazed seam of Al metal. Therefore, the high energy generated by either the temperature increase or the particle sputtering enable the Al atoms to overcome the energy barrier to form Al-O bonds with the O atoms on the Al2O3 ceramic surface, thereby improving the wettability of Al/Al2O3.

An improved preparation method for cross-sectional TEM specimens of films deposited on metallic substrates.

Cross-sectional TEM analysis is one of the most important techniques to characterize microstructures of films. However, the complex process, low efficiency, and low success rate of specimen preparation limit its application. This paper analyzed the main causes of low success rate and proposed an improved method for specimen preparation of films deposited on metallic substrates. This method consisting of twin-jet electropolishing and one-sided rocking ion milling is high in efficiency and success rate.