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.

Shift patterns, physical exercise, and Type 2 diabetes mellitus (T2DM): a prospective cohort study in China.

To examine the relationships between different shift patterns and Type 2 diabetes mellitus (T2DM) risk, and determine whether physical exercise reduced the incidence of T2DM in shift workers in the oil industry. Baseline data were collected from participants in May 2013 who were then followed for 4 years in a prospective cohort study. The cohort initially consisted of 3,002 workers and ultimately included 2,827 people. Baseline and follow-up questionnaires were sent to participants every 2 years (in May 2015 and May 2017) to update medical and lifestyle information during the follow-up period. The risk of T2DM among two shift workers [relative risk (RR) = 3.442, 95% CI: 1.904-6.799)], three shift workers (RR = 2.534, 95% CI: 1.484-4.571), and four shift workers (RR = 4.230, 95% CI: 2.680-7.518) was higher than that among day workers. An increasing trend was observed with respect to T2DM risk, with the lowest risk in three shift workers, moderate risk in two shift workers, and highest risk in four shift workers. In the interactive analysis between shift work and physical exercise, taking part in mild physical exercise increased the risk of T2DM for workers. Four shift workers who took part in mild physical exercise had an increased risk of T2DM. The relative excess risk due to interaction (RERI) was 33.769 (0.398-67.140). The attributable proportion due to interaction [API (%)] was 0.704 (0.529-0.880). The synergy index (SI) was 3.563 (1.900-6.683). Shift work is significantly correlated with increased incidence of T2DM. Risk of T2DM is lowest risk in three shift workers, moderate in two shift workers, and highest in four shift workers. Shift workers who participated in moderate and severe physical exercise had reduced risk of developing T2DM.

This study investigated the role of different shift patterns and physical exercise on type 2 diabetes mellitus (T2DM) risk factors of shift workers. We hypothesized that shift patterns would be correlated with the incidence of type 2 diabetes and that physical exercise would reduce the risk of type 2 diabetes. We studied 2,827 workers using a cohort study design following for 4 years. The study sample consisted of 1,249 fixed-day-shift workers, 650 three-shift workers, 297 two-shift workers, and 631 four-shift workers. We found that compared with fixed day shift workers, alternating shift workers were at an increased risk for developing T2DM. And moderate and severe physical exercise reduced the risk of T2DM in shift workers. We concluded that physical exercise is associated with decreased type 2 diabetes risk in shift workers, particularly when physical exercise is moderate and severe. The findings of the current study may assist enterprise management departments in developing diabetes interventions among shift workers.

The relationships of shift work, hair cortisol concentration and dyslipidaemia: a cohort study in China.

BACKGROUND: Currently, cardiovascular disease is the leading cause of death, and dyslipidaemia is an independent and modifiable major risk factor. Previous studies on shift work with dyslipidaemia and hair cortisol concentration (HCC) have yielded conflicting results. The aim of this study was to clarify the association between shift work, dyslipidaemia, and HCC. We further explored the mediating effect of HCC. METHODS: In this cohort study, baseline data were collected from participants in May 2013. The cohort included 2170 participants- 1348 shift workers and 822 non-shift workers- who were followed up for 6 years with four questionnaire surveys from July 2014, October 2015, and May to December 2019. Hair samples were collected from 340 participants during the baseline period for HCC testing with an automated radioimmunoassay. Dyslipidaemia was defined using the National Cholesterol Education Program Adult Treatment Panel III diagnostic criteria. RESULTS: Shift workers had a higher risk of dyslipidaemia than workers on the fixed day shift (two-shift RR = 1.408, 95% CI: 1.102-1.798; three-shift RR = 1.478, 95% CI: 1.134-1.926; four-shift RR = 1.589, 95% CI: 1.253-2.015). Additionally, shift workers had higher HCC levels than fixed day shift workers, with geometric mean concentration (GMC) ± geometric standard difference (GSD) = 2.625 ± 2.012 ng/g, two-shift GMC ± GSD = 3.487 ± 1.930 ng/g, three-shift GMC ± GSD = 2.994 ± 1.813 ng/g, and four-shift GMC ± GSD = 3.143 ± 1.720 ng/g. High HCC was associated with a high incidence of dyslipidaemia. After controlling for confounding factors, this study showed that HCC played a role in mediating dyslipidaemia in shift workers and accounted for 16.24% of the effect. CONCLUSIONS: Shift work was linked to increased risk of dyslipidaemia compared with fixed day shift work. Higher HCC was associated with a higher prevalence of dyslipidaemia. HCC had a significant mediating effect on dyslipidaemia in shift workers.

Relationships among N,N-dimethylformamide exposure, CYP2E1 and TM6SF2 genes, and non-alcoholic fatty liver disease.

OBJECTIVE: This study aimed to examine the relationships among N, N-dimethylformamide (DMF) exposure, cytochrome P4502E1 (CYP2E1) single nucleotide polymorphisms (SNPs) (rs2031920, rs3813867, rs6413432), transmembrane 6 superfamily member 2 (TM6SF2) SNP rs58542926 and non-alcoholic fatty liver disease (NAFLD). METHODS: Baseline data were collected from participants who were then followed for 5 years in a prospective cohort study. The cohort initially consisted of 802 workers and ultimately included 660 people, all of whom underwent annual occupational health examinations from 2010 to 2015. RESULTS: The above-threshold group (≥7.3 mg/m³ adjusted relative risk (RR)= 3.620, 95%CI 2.072-6.325) was significantly more likely to develop NAFLD than the below-threshold group (<7.3 mg/m³). The TM6SF2 SNP rs58542926 CT (adjusted RR=3.921, 95% CI 2.329-6.600, P = 0.000) and CT+TT (adjusted RR=4.385, 95% CI 2.639-7.287, P = 0.000) genotypes were risk factors for NAFLD, as compared with the TM6SF2 rs58542926 CC genotype. Each dose group (below-threshold group and above-threshold group) interacting with the genotype of TM6SF2 SNP rs58542926 had an adjusted RR from 7.764 (95% CI 3.272-18.420, P = 0.000) to 24.022 (95% CI 8.971-64.328, P = 0.000). The T allele of rs58542926 in the TM6SF2 gene may be a risk factor for susceptibility to DMF-induced NAFLD. CONCLUSION: Polymorphisms of TM6SF2 SNP rs58542926 may play an important role in susceptibility to NAFLD after exposure to DMF.