Additional file 1 of Association of length of service and job category with occupational health literacy of port employees in Shenzhen, China

Supplementary Material

Table_1_Impact of chronic benzene poisoning on aberrant mitochondrial DNA methylation: A prospective observational study.DOCX

Benzene is used as an industrial solvent, which may result in chronic benzene poisoning (CBP). Several studies suggested that CBP was associated with mitochondrial epigenetic regulation. This study aimed to explore the potential relation between CBP and mitochondrial DNA (mtDNA) methylation. This prospective observational study enrolled CBP patients admitted to Shenzhen Prevention and Treatment Center for Occupational Diseases hospital and healthy individuals between 2018 and 2021. The white blood cell (WBC), red blood cell (RBC), hemoglobin (HB), and platelet (PLT) counts and mtDNA methylation levels were measured using blood flow cytometry and targeted bisulfite sequencing, respectively. A total of 90 participants were recruited, including 30 cases of CBP (20 females, mean age 43.0 ± 8.0 years) and 60 healthy individuals (42 females, mean age 43.5 ± 11.5 years). This study detected 168 mitochondrial methylation sites >0 in all study subjects. The mtDNA methylation levels in the CBP cases were lower than the healthy individuals [median ± interquartile-range (IQR), 25th percentile, 75th percentile: (1.140 ± 0.570, 0.965, 1.535)% vs. median ± IQR, 25th percentile, 75th percentile: (1.705 ± 0.205,1.240,2.445)%, P < 0.05]. Additionally, the spearman correlation analysis showed that the mtDNA methylation levels were positively correlated with the counts of circulating leukocytes [WBC (r = 0.048, P = 0.036)] and platelets [PLT (r = 0.129, P < 0.01)]. We provided solid evidence of association between CBP and aberrant mtDNA methylation.</p

The Dose–Response Decrease in Heart Rate Variability: Any Association with the Metabolites of Polycyclic Aromatic Hydrocarbons in Coke Oven Workers?

<div><h3>Background</h3><p>Air pollution has been associated with an increased risk of cardiopulmonary mortality and decreased heart rate variability (HRV). However, it is unclear whether coke oven emissions (COEs) and polycyclic aromatic hydrocarbons (PAHs) are associated with HRV.</p> <h3>Objectives</h3><p>Our goal in the present study was to investigate the association of exposure to COEs and the urinary metabolite profiles of PAHs with HRV of coke oven workers.</p> <h3>Methods</h3><p>We measured benzene soluble matter, carbon monoxide, sulfur dioxide, particulate matters, and PAHs at different workplaces of a coke oven plant. We determined 10 urinary PAH metabolites and HRV indices of 1333 workers using gas chromatography–mass spectrometry and a 3-channel digital Holter monitor, respectively.</p> <h3>Results</h3><p>Our results showed that there was a significant COEs-related dose-dependent decrease in HRV, and an inverse relationship between the quartiles of urinary 2-hydroxynaphthalene and five HRV indices (<em>p</em>_trend<0.01 for all). After adjustment for potential confounders, elevation per interquartile range (IQR) (1.81 µg/mmol creatinine) of urinary 2-hydroxynaphthalene was associated with a 5.46% (95% CI, 2.50–8.32) decrease in standard deviation of NN intervals (SDNN). As workers worked more years, SDNN gradually declined in the same quartiles of 2-hydroxynaphthalene levels (<em>p</em>_trend = 1.40×10⁻⁴), especially in workers with the highest levels of 2-hydroxynaphthalene.</p> <h3>Conclusions</h3><p>Occupational exposure to COEs is associated with a dose-response decrease in HRV. In particular, increased exposure to 2-hydroxynaphthalene is associated with significantly decreased HRV. Increase of working years and exposure levels has resulted in a gradual decline of HRV.</p> </div

Percent change (95% CI) in HRV measures for an interquartile range increase in urinary 2-hydroxynaphthalene.

<p>Percent change (95% CI) in HRV measures for an interquartile range increase in urinary 2-hydroxynaphthalene.</p

Levels of environmental pollutants in different groups (mean ± SD).

<p>BSM: benzene soluble matter; CO: carbon monoxide; SO₂: sulfur dioxide; PM: particulate matter; PAHs: polycyclic aromatic hydrocarbons.</p

Urinary PAH metabolites and HRV indices of the workers in different groups.

<p>HF, high frequency; LF, low frequency; rMSSD, root mean square of successive differences in adjacent NN intervals; SDNN: standard deviation of NN intervals; TP: total power.</p>*<p>Simple linear regression for the trend of urinary PAH metabolites with the exposure levels.</p>†<p>Multivariate linear regression for the trend of HRV with the exposure levels with adjustment for age, sex, working years, smoking status, alcohol use, BMI, exercise and hypertension.</p

HRV indices of the workers stratified by the quartiles of each urinary PAH metabolite levels.

*<p>Multivariate analysis of covariance for the differences between different groups with adjustment for age, sex, working years, smoking status, alcohol use, BMI, exercise and hypertension.</p>†<p>Multivariate linear regression for the trend of HRV with the exposure levels with adjustment for age, sex, working years, smoking status, alcohol use, BMI, exercise and hypertension.</p

Joint effects of the quartiles of the working years and the quartiles of urinary 2-hydroxynaphthalene levels in SDNN.

<p>2-hydroxynaphthalene: Q1 (<0.84 µg/mmol creatinine), Q2 (0.84–1.56 µg/mmol creatinine), Q3 (1.57–2.65 µg/mmol creatinine) and Q4 (>2.65 µg/mmol creatinine). The cutpoint (Q1–Q4) of the working years represent the quartiles of the working years in the quartiles of urinary 2-hydroxynaphthalene levels. Working years in Q1 of 2-hydroxynaphthalene levels: Q1 (<13.83years), Q2 (13.83–18.79years), Q3 (18.80–26.92years), and Q4 (>26.92years); working years in Q2 of 2-hydroxynaphthalene levels: Q1 (<15.42years), Q2 (15.42–19.42years), Q3 (19.43–27.75years), and Q4 (>27.75years); working years in Q3 of 2-hydroxynaphthalene levels: Q1 (<16.92years), Q2 (16.92–21.17years), Q3 (21.18–29.75years), and Q4 (>29.75years); working years in Q4 of 2-hydroxynaphthalene levels: Q1 (<15.92years), Q2 (15.92–21.17years), Q3 (21.18–29.83years), and Q4 (>29.83years). *<i>P</i><0.01, compared with the group from Q1 of working years+Q1 of 2-hydroxynaphthalene levels. <i>P</i>_trend = 1.40×10⁻⁴.</p

General characteristics of the workers in different groups.

<p>BMI: body mass index.</p>*<p>One-way ANOVA for the differences between different exposure groups.</p>†<p>Chi-square tests for the differences in the distribution frequencies between different exposure groups.</p

Genotype score of top SNPs with TC, TG, LDL, HDL levels.

<p>The genotype score represents the number of risk alleles (the alleles associated with higher TC or TG or LDL or lower HDL) at each of eight SNPs. The eight SNPs were rs11207995 (DOCK7), rs10045497 (HMGCR), rs507666 (ABO), rs328 (LPL), rs651821 (APOA1/C3/A4/A5), rs1160985 (TOMM40), rs2043085 (LIPC) and rs3764261 (CETP). The height of the bars is the mean values of individuals with a specific genotype score. The error bars are Means ± SD of lipid levels in each group. </p