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- Gliga, Anda R., et al.
(författare)
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Exposure to Mild Steel Welding and Changes in Serum Proteins With Putative Neurological Function—A Longitudinal Study
- 2020
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Ingår i: Frontiers in Public Health. - : Frontiers Media SA. - 2296-2565. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Welders are exposed to high levels of metal particles, consisting mainly of iron and manganese (Mn) oxide. Metal particles, especially those containing Mn can be neurotoxic. In this exploratory study, we evaluated associations between welding and expression of 87 putative neurology-related proteins in serum in a longitudinal approach. The study cohort from southern Sweden included welders working with mild steel (n = 56) and controls (n = 67), all male and non-smoking, which were sampled at two timepoints (T1, T2) 6-year apart. Observed associations in the longitudinal analysis (linear mixed models) were further evaluated (linear regression models) in another cross-sectional sample which included welders (n = 102) and controls (n = 89) who were sampled only once (T1 or T2). The median respirable dust levels for welders after adjusting for respiratory protection was at T1 0.6 (5–95 percentile: 0.2–4.2) and at T2 0.5 (0.1–1.8) mg/m3. The adjusted median respirable Mn concentration was at T2 0.049 mg/m3 (0.003–0.314) with a Spearman correlation between adjusted respirable dust and respirable Mn of rS = 0.88. We identified five neurology-related proteins that were differentially expressed in welders vs. controls in the longitudinal sample, of which one (nicotinamide/nicotinic acid mononucleotide adenylyltransferase 1; NMNAT1) was also differentially expressed in the cross-sectional sample. NMNAT1, an axon-protective protein linked to Alzheimers disease, was upregulated in welders compared with controls but no associations were discerned with degree of exposure (welders only: years welding, respirable dust, cumulative exposure). However, we identified five additional proteins that were associated with years welding (GCSF, EFNA4, CTSS, CLM6, VWC2; welders only) both in the longitudinal and in the cross-sectional samples. We also observed several neurology-related proteins that were associated with age and BMI. Our study indicates that low-to-moderate exposure to welding fumes is associated with changes in circulating levels of neurology-related proteins.
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| 3. |
- Gliga, Anda R., et al.
(författare)
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Mild steel welding is associated with alterations in circulating levels of cancer-related proteins
- 2019
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Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 93:12, s. 3535-3547
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Tidskriftsartikel (refereegranskat)abstract
- Welding fumes were recently classified as carcinogenic to humans and worldwide millions work as welders or perform welding operations. The purpose of this study was to identify new biomarkers of welding-induced carcinogenesis. We evaluated a panel of 91 putative cancer-related proteins in serum in a cohort of welders working with mild steel (n = 77) and controls (n = 94) from southern Sweden sampled on two occasions 6-year apart using a longitudinal analysis (linear mixed models). The significant results from the longitudinal analysis were tested for reproducibility in welders (n = 88) and controls (n = 69) sampled once during the same sampling period as timepoint 1 or timepoint 2 (linear regression models), i.e., in a cross-sectional setting. The models were adjusted for age, body-mass index, and use of snus. All study participants were non-smokers at recruitment. Exposure to welding fumes was assessed using questionnaires and respirable dust measurement in the breathing zone that was adjusted for personal respiratory protection equipment. The median respirable dust in welders was 0.7 (0.2–4.2) and 0.5 (0.1–1.9) mg/m3 at the first and second timepoints, respectively. We identified 14 cancer-related proteins that were differentially expressed in welders versus controls in the longitudinal analysis, out of which three were also differentially expressed in the cross-sectional analysis (cross-sectional group). Namely, syndecan 1 (SDC1), folate receptor 1 (FOLR1), and secreted protein acidic and cysteine rich (SPARC) were downregulated, in welders compared with controls. In addition, FOLR1 was negatively associated with years welding. Disease and function analysis indicated that the top proteins are related to lung cancer as well as cell invasion and migration. Our study indicates that moderate exposure to welding fumes is associated with changes in circulating levels of putative cancer-related proteins, out of which FOLR1 showed a clear dose–response relationship. It is, however, unclear to which extent these changes are adaptive or potential early biomarkers of cancer.
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| 6. |
- Hedmer, Maria, et al.
(författare)
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Diesel Exhaust Exposure Assessment Among Tunnel Construction Workers—Correlations Between Nitrogen Dioxide, Respirable Elemental Carbon, and Particle Number
- 2017
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Ingår i: Annals of Work Exposures and Health. - : Oxford University Press (OUP). - 2398-7308 .- 2398-7316. ; 61:5, s. 539-553
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Occupational exposure to diesel exhaust is common due the widespread use of dieselpowered combustion engines. Diesel exhaust is chemically complex and consists of thousands of compounds present as gases and particulate matter. Both nitrogen dioxide (NO2) and elemental carbon(EC) have been used as markers for diesel exhaust exposure. Currently EC is regarded as the best surrogate of diesel exhaust. The objective was to quantify the occupational exposure to diesel exhaust in underground tunnel construction work using a multi-metric approach, and to investigate the correlations between NO2, respirable EC, respirable organic carbon (OC), respirable total carbon(TC), respirable dust (RD), and particle number. Also, the use of NO2 as a proxy for diesel exhaust was evaluated, how much of the variability in the diesel exhaust exposure was attributed to within and between individual factors and if there was a difference between expert and self-administered measurements of NO2. Methods: The personal exposure to diesel exhaust was assessed by expert supervised measurements of NO2, EC, OC, TC, RD and particle number in the breathing zones of underground tunnel workers. Stationary sampling of NO2, EC, OC, TC, RD, size-fractioned mass concentration, and particle number were conducted. The personal and stationary measurements were conducted on threeoccasions simultaneously. The workers measured their exposure by repeated self-administered measurements of NO2. The self-administered measurements were performed twice for each worker with at least one month lag between the samplings. Results: In the simultaneous sampling of diesel exhaust, the geometric mean (GM) concentration of NO2 and respirable EC were 72 μg m−3 (10th–90th percentile 34–140 μg m−3) and 2.6 μg m−3 (10th–90th percentile 1.6–7.3 μg m−3), respectively. The GM for OC and TC was 28 μg m−3 (10th–90th percentile 20–42 μg m−3) and 31 μg m−3 (10th–90th percentile 20–50 μg m−3), respectively. The GM for RD and particle number was 180 μg m−3 (10th–90th percentile 20–530 μg m−3) and 47 900 cm−3 (10th–90th percentile (27 500–94 100 cm−3), respectively. A significant correlation was found between NO2 and respirable EC [Spearman’s correlation r = 0.53 (P = 0.05)]. The within-worker variability of NO2 was 45.5% and the between-worker variability was 54.5%. The self-administered measured concentrations of NO2 (GM 70 μg m−3) did not statistically differ from the NO2 concentrations measured by an expert (P > 0.35).Conclusion: The diesel exhaust exposure in tunnel construction work was low. A significant correlation between NO2 and EC was observed. This indicates that NO2 could be used as a proxy for diesel exhaust in tunnel work if diesel exhaust is the only source of NO2 and if the ratio between EC and NO2 is known and constant. Passive sampling of NO2 is much easier and cheaper to perform compared with active sampling of EC. It is possible to utilize self-administered NO2 measurements in extreme and inaccessible work environments. This study adds support to continued use of NO2 as an exposure marker in combination with EC for diesel exhaust exposure. In tunnel construction work, the variability in the diesel exhaust exposure was high both between- and within-workers.
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| 7. |
- Hedmer, Maria, et al.
(författare)
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Exposure and Emission Measurements During Production, Purification, and Functionalization of Arc-Discharge-Produced Multi-walled Carbon Nanotubes.
- 2014
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Ingår i: Annals of Occupational Hygiene. - : Oxford University Press (OUP). - 1475-3162. ; 58:3, s. 355-379
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Tidskriftsartikel (refereegranskat)abstract
- Background: The production and use of carbon nanotubes (CNTs) is rapidly growing. With increased production, there is potential that the number of occupational exposed workers will rapidly increase. Toxicological studies on rats have shown effects in the lungs, e.g. inflammation, granuloma formation, and fibrosis after repeated inhalation exposure to some forms of multi-walled CNTs (MWCNTs). Still, when it comes to health effects, it is unknown which dose metric is most relevant. Limited exposure data for CNTs exist today and no legally enforced occupational exposure limits are yet established. The aim of this work was to quantify the occupational exposures and emissions during arc discharge production, purification, and functionalization of MWCNTs. The CNT material handled typically had a mean length <5 μm. Since most of the collected airborne CNTs did not fulfil the World Health Organization fibre dimensions (79% of the counted CNT-containing particles) and since no microscopy-based method for counting of CNTs exists, we decided to count all particle that contained CNTs. To investigate correlations between the used exposure metrics, Pearson correlation coefficient was used.
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| 10. |
- Hedmer, Maria, et al.
(författare)
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Real-Time Emission and Exposure Measurements of Multi-walled Carbon Nanotubes during Production, Power Sawing, and Testing of Epoxy-Based Nanocomposites
- 2022
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Ingår i: Annals of Work Exposures and Health. - : Oxford University Press (OUP). - 2398-7308 .- 2398-7316. ; 66:7, s. 878-894
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Tidskriftsartikel (refereegranskat)abstract
- The use of manufactured nanomaterials is increasing globally. Although multi-walled carbon nanotubes (CNTs) are used in a wide range of applications, only limited data are available on emissions and exposures during CNT composite production. No exposure data using portable aethalometers in the personal breathing zone (PBZ) to monitor occupational exposure to CNTs have yet been published. The aim of this study was to characterize emissions of and exposures to CNTs during CNT composite production, sawing, and shear testing. We also investigated whether real-time aethalometer measurements of equivalent black carbon (eBC) could be used as a proxy filter sampling of elemental carbon (EC). The presence of CNTs as surface contamination in the production facility was monitored since this could contribute to airborne exposure.Methods: During CNT composite production in an industrial setting including both chemical and manufacturing laboratories, different work tasks (WTs) were studied with a combination of directreading instruments (aethalometer, aerodynamic particle sizer, condensation particle counter) and filter-based methods. Measurements were performed to monitor concentrations in the emission zone (EZ), PBZ, and background zone. The filter samples were analysed for EC and fibre concentration of CNTs using scanning electron microscopy (SEM). Additionally, surfaces in the facility were tape sampled for monitoring of CNT contamination, and analysed with SEM.Results: Clear eBC peaks were observed in the PBZ during several WTs, most clearly during open handling of CNT powder. Power sawing emitted the highest particle number concentration in the EZ of both nanoparticles and coarse particles, but no individual airborne CNTs, agglomerates, or aggregates were detected. Airborne CNTs were identified, for example, in a filter sample collected in the PBZ of a worker during mixing of CNT epoxy. The airborne CNT particles were large agglomerates which looked like porous balls in the SEM images. Significant EC exposures were found in the inhalable fraction while all respirable fractions of EC were below detection. The highest inhalable EC concentrations were detected during the composite production. No significant correlation was found between inhalable EC and eBC, most likely due to losses of large EC containing particles in the sampling lines and inside the eBC monitor. In total, 39 tape samples were collected. Surface contamination of CNTs was detected on eight surfaces in the chemical and manufacturing laboratories, mainly in the near-field zone. Elongated CNT-like features were detected in the sawdust after sawing of CNT composite.Conclusions: Characterization of a workplace producing CNT composite showed that open handling of the CNT powder during weighing and mixing of CNT powder material generated the highest particle emissions and exposures. The portable direct-reading aethalometer provided time-resolved eBC exposure data with complementary information to time-integrated EC filter samples by linking peak exposures to specific WTs. Based on the results it was not possible to conclude that eBC is a good proxy of EC. Surface contamination of CNTs was detected on several surfaces in the near-field zone in the facility. This contamination could potentially be resuspended into the workplace air, and may cause secondary inhalation exposure.
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