Rheumatoid Arthritis in Silica-Exposed Workers

Few studies have examined rheumatoid arthritis (RA) risk and severity in Korean workers exposed to silica. We compared the hospitalization risk of RA between silica-exposed workers and the general Korean population. The study cohort consisted of male workers exposed to silica who had undergone at least one silica-associated special medical examination between 1 January 2000 and 31 December 2004 (N = 149,948). The data were from the Korea Occupation Safety and Health Agency. RA morbidity based on hospital admission records was estimated from 2000 to 2005 using the Korea National Health Insurance Service claims data. The standardized admission ratio (SAR) was calculated by dividing the observed number of admissions in silica-exposed workers by the expected number of admissions in the general reference population. For the sum of “Seropositive rheumatoid arthritis” (M05) and “Other rheumatoid arthritis” (M06), the SAR was higher in the silica-exposed group (1.34, 95% CI 1.08–1.64). For M05, workers with <10 years of silica exposure had a significantly higher SAR (2.54, 95% CI 1.10–5.01) than the general population. More silica-exposed workers without a diagnosis of pneumoconiosis were hospitalized for RA than the general population. Our analysis reaffirms the link between silica exposure and RA and suggests that the severity of RA is increased by silica. Further studies of silica-exposed workers with longer follow-up are needed.

PIG-A gene mutation as a genotoxicity biomaker in polycyclic aromatic hydrocarbon-exposed barbecue workers

Background The PIG-A gene mutation assay is a valuable tool for measuring in vivo gene mutations in blood cells. The human PIG-A assay, used as a potential genotoxicity biomarker, is minimally invasive, sensitive, and cost-efficient; however, the relationship between carcinogen exposure and PIG-A mutations is not well understood. Methods We investigated the genotoxic effect of red blood cells using PIG-A assay and lymphocyte cytokinesis-block micronucleus test in barbecue restaurant workers (N = 70) exposed to polycyclic aromatic hydrocarbons (PAHs) and self-identified healthy control subjects (N = 56). Urinary PAH metabolites were measured to evaluate internal exposure levels. Results Multivariate Poisson regression showed that the PAH-exposed workers exhibited significantly higher PIG-A mutant frequency (MF) (8.04 ± 6.81 × 10− 6) than did the controls (5.56 ± 5.26 × 10− 6) (RR = 0.707, 95% CI: 0.615–0.812, P < 0.001). These results indicate that PAH exposure is a risk factor for elevated PIG-A MF. The frequencies of micronuclei (MN) and nuclear buds (NBUD) in the PAH-exposed workers (MN: 3.06 ± 2.07 ‰, NBUD: 1.38 ± 1.02 ‰) were also significantly higher than in the controls (MN: 1.46 ± 0.64 ‰, P < 0.001; NBUD: 0.70 ± 0.60 ‰, P < 0.001). Additionally, PIG-A MFs showed better associations with several urinary hydroxylated PAH metabolites (P2-OH-Flu = 0.032, r2-OH-Flu = 0. 268; P2-OH-Phe = 0.022, r2-OH-Phe = 0.286; P3-OH-Phe = 0.0312, r3-OH-Phe = 0.270; P4-OH-Phe = 0.018, r4-OH-Phe = 0.296), while the increase in MN, NPB, and NBUD frequencies was not associated with any OH-PAH metabolites; and high-PAH-exposed workers showed the highest PIG-A MFs. Furthermore, there was a significant association between PIG-A MF and PAH exposure levels (Chi-square test for trend, P = 0.006). Conclusions Our results indicate that an increase in PIG-A MF in barbecue workers could reflect the response to PAH exposure, providing evidence of its potential as a genotoxicity biomarker in human risk assessment.

Telomere length in peripheral leukocytes is a sensitive marker for assessing genetic damage among workers exposed to isopropanol, lead and noise: the case of an electronics manufacturer

Background Workers in electronics manufacturers may be exposed to various occupational hazards such as isopropanol, lead, and noise. Telomeres are special segments of cap-like DNA protein complex at end of liner chromosomes in eukaryotic cells. Telomere length is a potential marker of genetic damage. The aim of this study is to evaluate the effect of occupational hazards on the relative telomere length (rTL) of peripheral blood cells of workers in an electronics manufacturer, and to explore whether relative telomere length could be a biomarker for assessing genetic damage in the electronics manufacturing industry. Methods We investigated a large-scale electronics manufacturer in the Pearl River Delta Region. We ultimately collected 699 qualified workers (248 with isopropanol exposure, 182 with lead exposure, 157 with noise exposure, and 112 controls). During physical examination of the workers, we gave them questionnaires to understand their health statuses and living habits. We also collected peripheral blood samples from these workers to test exposure levels and rTL in the leucocytes. Results The concentrations of air isopropanol in all monitored workshops was 25.3 mg/m3 and air lead smoke was 0.020 mg/m3. The maximum equivalent continuous A sound level noise exposure position was 82.2dB (A). All were lower than those in the Occupational Exposure Limits in Workplaces in China. Urinary acetone in the isopropanol exposed group was 1.04 (0, 1.50) mg/L, and cumulative urinary acetone was 1.48 (0, 5.09) mg-years/L. Blood lead levels (BLLs) were 28.57 (22.77, 37.06) µg/dL, and cumulative blood lead levels (CBLLs) were 92.75 (55.47, 165.13) µg-years/dL. rTL was different between occupational exposed workers and controls: rTL was 0.140 units (95 % CI: 0.022, 0.259) shorter in lead exposed workers and 0.467 units (95 % CI: 0.276–0.658) shorter in noise exposed workers compared to the controls. There is no statistical difference in rTL between isopropanol exposure workers and the controls. In order to elucidate the relationship between rTL and occupational hazards exposure, we divided the isopropanol exposure workers into three groups (0, ~1.43 mg/L, and >1.43 mg/L). None of the rTL difference was statistically significant among exposed workers at different uroacetone levels (P>0.05). The groups with ≥100 µg/dL blood lead had shorter rTL than the group with blood lead below 100 µg/dL (F=4.422, P=0.013). We incorporated age, gender, birthplace, race, education level, smoking, and alcohol consumption into the linear regression equation. Only blood lead concentration (X) was entered into the regression equation, yielding a multivariate linear regression equation of Y=0.397-0.124X (F=8.091, P=0.005). Workers with different hearing loss also had statistically significant differences in rTL (F=5.731, P=0.004). rTL was a protective factor for the occurrence of noise-induced hearing loss (NIHL). The longer the rTL, the lower the risk of NIHL [OR=0.64 (0.42, 0.98)]. Conclusions rTL was shorter in lead exposed workers and noise exposed workers, and it was a protective factor for the occurrence of the noise-induced hearing loss. Thus, rTL of peripheral blood may be a sensitive marker of genetic damage among workers in environments with lead and noise exposure.

Rounded atelectasis after exposure to refractory ceramic fibres (RCF)

Background Refractory Ceramic fibres (RCF) are man-made mineral fibres used in high performance thermal insulation applications. Analogous to asbestos fibres, RCF are respirable, show a pleural drift and can persist in human lung tissue for more than 20 years after exposure. Pleural changes such as localised or diffuse pleural thickening as well as pleural calcification were reported. Result A 45 years old man worked in high performance thermal insulation applications using refractory ceramic fibres (RCF) for almost 20 years. During a occupational medical prophylaxis to ensure early diagnosis of disorders caused by inhalation of aluminium silicate fibres with X-ray including high-resolution computed tomography (HRCT), bilateral pleural thickening was shown and a pleural calcification next to a rounded atelectasis was detected. Asbestos exposure could be excluded. In pulmonary function test a restrictive lung pattern could be revealed. In work samples scanning electron microscopy (SEM) including energy dispersive X-ray analysis (EDX) classified used fibres as aluminium silicate fibres. X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) showed crystalline as well as amorphous fibres. Conclusions A comprehensive lung function analysis and in case of restrictive lung disorders additional CT scans are needed in RCF exposed workers in accordance to the guidelines for medical occupational examinations comparable to asbestos exposed workers.

A rapid point of care CC16 kit for screening of occupational silica dust exposed workers for early detection of silicosis/silico-tuberculosis

Silicosis is an irreversible, incurable and progressive occupational disease caused by prolonged exposure to crystalline-silica dust while working in the relevant industries. Conventionally diagnosis is done by chest radiology, often in an advanced stage as early symptoms often go unnoticed. Early detection and necessary intervention (secondary prevention) could be a realistic possible control strategy for controlling silicosis as no effective treatment is available to stop and/or reverse the pathological process. Additionally, these patients are also vulnerable to pulmonary tuberculosis, which often becomes difficult to treat and with uncertain treatment outcome. Considering India has a huge burden of silicosis and silico-tuberculosis, a rapid and inexpensive screening method was realized to be an urgent need for early detection of silicosis among silica dust exposed workers. Serum club cell protein 16 (CC16) is evidenced to be a useful proxy screening marker for early detection of silicosis as evidenced from the recent research work of ICMR-National Institute of Occupational Health (ICMR-NIOH), India. In this study a lateral-flow assay for semi-quantitative estimation of serum CC16 level was developed. The detection was performed using gold nanoparticles conjugated anti-CC16 monoclonal antibodies. A sum of 106 serum samples was tested to do the performance evaluation of the assay. A concentration of 6 ng/ml or less produced one band, 6.1–9 ng/ml produced two bands, while more than 9 ng/ml produced all the three bands at the test zone. The sensitivity of the assay was 100% while the specificity was 95%. This assay may be used as a sensitive tool for periodic screening of silica dust exposed vulnerable workers for early detection of silicosis in them.

Long non-coding RNA ENST00000414355 as a biomarker of cadmium exposure regulates DNA damage and apoptosis

Human exposure to cadmium (Cd) may induce severe effects in different organs. Recent studies suggest that long non-coding RNAs (lncRNAs) are closely involved in the pathophysiological mechanisms of Cd-related diseases. This study evaluated the use of lncRNA (ENST00000414355) as an expression signature of Cd exposure and assessed its ability to modulate DNA damage and apoptosis by measuring the expression of ATM serine/threonine kinase (ATM) and mitochondrial membrane potential (ΔΨm) in Cd-exposed workers. A total of 139 (74 non-smokers and 65 smokers) participants from a Cd battery manufacturer were included in the study. Venous blood samples were collected to determine the blood Cd level and detect blood ENST00000414355 and its target gene (ATM) using real-time reverse transcription-polymerase chain reaction (qRT-PCR). Mitochondrial membrane potential was used to assess the Cd effect on mitochondrial permeability. Our results indicated a significant positive correlation between blood Cd level and lncRNA-ENST00000414355 and ATM expression and a significant negative correlation between blood Cd level and ΔΨm ( p < 0.0001). Moreover, significant correlations were observed between the expression of lncRNA-ENST00000414355 and ATM expression and ΔΨm ( p < 0.0001). Statistical significance was found in the blood Cd level, lncRNA-ENST00000414355 expression, ATM expression, and ΔΨm ( p < 0.0001) between smokers and non-smokers. This study confirmed the upregulation of the lncRNA-ENST00000414355 expression, DNA damage-checkpoint-related gene (ATM), and decreased ΔΨm in Cd-exposed workers. Thus, lncRNA-ENST00000414355 may serve as a valuable biomarker for the exposure and toxicity of Cd.

Noise-induced Hearing Loss and Hypertension Among Occupational Noise-exposed Workers: a Pilot Study Based on Baseline Data

Background: Noise is a widespread occupational hazardous factor affecting the health of workers in occupational health field. Noise-induced hearing loss (NIHL) and hypertension are the important biological adverse effects caused by occupational noise exposure. This study aimed to determine the binaural high frequency (3, 4, and 6 kHz) threshold on average (BHFTA) and levels of systolic blood pressure (SBP) and diastolic blood pressure (DBP), to assess the prevalence of NIHL and hypertension and determine the factors influencing the risk of both, and to evaluate the association between NIHL and hypertension among occupational noise-exposed workers. Methods: Questionnaire and occupational health checkup were performed to collect the personal information and physical examination data. Finally, baseline data from 42,588 occupational noise-exposed workers were analyzed. Noise intensity in the workplaces was measured using sound level meter. Pure tone audiometry (PTA) was measured at 3, 4 and 6 kHz using diagnostic audiometer. Moreover, blood pressure level was measured using automated sphygmomanometer. Results: The mean levels of BHFTA, SBP, and DBP were 23.09 ± 11.32 dB, 126.85 ± 15.94 mm Hg, 79.94 ± 11.61 mm Hg. Of the 42,588 subjects, the prevalence of NIHL and hypertension were 24.38% (n = 10,383) and 25.40% (n = 10,816). The results suggested that higher risk of NIHL and hypertension were more likely to be the subgroups of male gender, aged > 35 years, noise exposure time > 5 years, noise exposure level > 85 dB (A) and smoking. The BHFTA, SBP, and DBP levels increased with the age, noise exposure time and exposure level (Ptrend < 0.001). Besides, similar trends were also observed in the prevalence of NIHL and hypertension. Furthermore, there was a significant association of NIHL with hypertension. We found that 32.25% (n = 3,348) workers with NIHL had hypertension. The mean levels of SBP and DBP in NIHL workers were significantly higher than those with normal hearing (P < 0.001). Besides, workers with NIHL had a significantly higher risk of developing hypertension than normal hearing workers (adjusted OR = 1.07, 95%CI = 1.02-1.13). Conclusion: Our current findings suggest that the prevalence of NIHL and hypertension are high in the studied workers and occupational noise exposure is an important factor. Therefore, it is urgent to reduce noise exposure in the workplaces and to strengthen industrial noise monitoring.