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 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.

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.

Vessel density ratio: A novel approach to identify "culprit" coronary lesion by spiral computed tomography.

BACKGROUND AND OBJECTIVE: We hypothesized that a "culprit" lesion in acute coronary syndrome (ACS) should have low overall vessel lumen and plaque density on multidetector computed tomography-assisted coronary angiography (MDCTA) because of lower calcification and the presence of occlusive thrombus. However, thrombi and calcification both can themselves blur the demarcation between vessel wall and lumen. If we calculated a "vessel density ratio" (VDR) obtained by measuring the mean density of contrast-enhancement within a region of interest (ROI), which includes the vessel wall, lumen, plaque, and thrombus, and comparing that with the aortic root mean density acting as a reference point, this ratio may be more convenient, standardized, and reproducible to test the feasibility of VDR in identifying "culprit" lesions in ACS. METHODS: Sixty-four patients-21 exertional angina; 17 unstable angina/non-ST elevation myocardial infarction (NSTEMI); 26 ST elevation myocardial infarction (STEMI)-provided 188 diseased segments on conventional angiography. All underwent MDCTA within a week of angiography. ROI was mapped out from maximum intensity projections of diseased segments in planar view. RESULTS: One hundred seventy-four segments were evaluated. Patients who presented with ACS (STEMI and unstable angina/non-ST elevation myocardial infarction) had lower mean VDR compared to patients with exertional angina (0.58 vs. 0.66 vs. 0.81; P < 0.001). Culprit lesions in ACS patients also had the lowest mean VDR when compared to nonculprit lesions and lesions in patients without ACS (0.51 vs. 0.68 vs. 0.81; P < 0.001). CONCLUSIONS: VDR is a new, convenient, and standardized approach in identifying "culprit" lesions by MDCTA.