Exposure to welding fumes is associated with acute systemic inflammatory responses

Relationship between pulmonary and systemic markers of exposure to multiple types of welding particulate matter

Welding results in a unique and complex occupational exposure. Recent epidemiological studies have shown an increased risk of cardiovascular disease following welding fume exposure. In this study, we compared the induction of pulmonary and systemic inflammation following exposure to multiple types of welding fumes. Mice were exposed to 340μg of manual metal arc stainless steel (MMA-SS), gas metal arc-SS (GMA-SS) or GMA-mild steel (GMA-MS) by pharyngeal aspiration. Mice were sacrificed at 4 and 24h post-exposure to evaluate various parameters of pulmonary and systemic inflammation. Alterations in pulmonary gene expression by a custom designed TaqMan array showed minimal differences between the fumes at 4h. Conversely at 24h, gene expression changes were further increased by SS but not GMA-MS exposure. These findings were associated with the surrogate marker of systemic inflammation, liver acute phase gene induction. Interestingly, stress response genes in cardiovascular tissues were only increased following MMA-SS exposure. These effects were related to the initial level of pulmonary cytotoxicity, as measured by lactate dehydrogenase activity, which was greatest following MMA-SS exposure. In conclusion, varying types of welding fumes elicit quantitatively different systemic inflammatory and/or stress responses.

Acute decrease in HDL cholesterol associated with exposure to welding fumes

OBJECTIVE

To investigate acute changes in circulating lipids after exposure to relatively high levels of particulate matter through welding.

METHODS

Using a repeated measures panel study, lipid levels before and after welding and personal exposures to fine particulate matter (PM2.5) were measured in 36 male welders over 63 exposure and/or control days.

RESULTS

There was a trend toward decrease in HDL (-2.3 mg/dL, P = 0.08) 18 hours after welding. This effect became significant (-2.6 mg/dL, P = 0.05) after adjustment for possible confounders. The effect was strongest (-4.3 mg/dL, P = 0.02) among welders who did not weld the day before the study. There were no significant changes in other lipids associated with welding or PM2.5 exposure.

CONCLUSION

Welding exposure was associated with an acute decrease in circulating HDL, which may relate to the inflammatory and proatherosclerotic effects of fine particle exposure.

Inhalation exposure of gas-metal arc stainless steel welding fume increased atherosclerotic lesions in apolipoprotein E knockout mice

Epidemiological studies suggest that welding, a process which generates an aerosol of inhalable gases and metal rich particulates, increases the risk for cardiovascular disease. In this study we analyzed systemic inflammation and atherosclerotic lesions following gas metal arc-stainless steel (GMA-SS) welding fume exposure. Apolipoprotein E knockout (apoE(-/-)) mice, fed a Western diet, were exposed to GMA-SS at 40mg/m(3) for 3h/day for ten days (∼8.26μg daily alveolar deposition). Mice were sacrificed two weeks after exposure and serum chemistry, serum protein profiling and aortic lesion area were determined. There were no significant changes in serum total cholesterol, triglycerides or alanine aminotransferase. Serum levels of uric acid, a potent antioxidant, were decreased perhaps suggesting a reduced capacity to combat systemic oxidative stress. Inflammatory serum proteins interleukin 1 beta (IL-1β) and monocyte chemoattractant protein 3 (MCP-3) were increased two weeks after GMA-SS exposure. Analysis of atherosclerotic plaques showed an increase in lesion area as the result of GMA-SS exposure. In conclusion, GMA-SS exposure showed evidence of systemic inflammation and increased plaque progression in apoE(-/-) mice. These results complement epidemiological and functional human studies that suggest welding may result in adverse cardiovascular effects.

Statistical modeling to determine sources of variability in exposures to welding fumes

BACKGROUND/AIMS

Exposures to total particulate matter (TP) and manganese (Mn) received by workers during welding and allied hot processes were analyzed to assess the sources and magnitudes of variability.

METHODS

Compilation of data from several countries identified 2065 TP and 697 Mn measurements for analysis. Linear mixed models were used to determine fixed effects due to different countries, industries and trades, process characteristics, and the sampling regimen, and to estimate components of variance within workers (both intraday and interday), between workers (within worksites), and across worksites.

RESULTS

The fixed effects explained 55 and 49% of variation in TP and Mn exposures, respectively. The country, industry/trade, type of ventilation, and type of work/welding process were the major factors affecting exposures to both agents. Measurements in the USA were generally higher than those in other countries. Exposure to TP was 67% higher in enclosed spaces and 43% lower with local exhaust ventilation (LEV), was higher among boilermakers and was higher when either a mild-steel base metal or a flux cored consumable was used. Exposure to Mn was 750% higher in enclosed spaces and 67% lower when LEV was present. Air concentrations of Mn were significantly affected by the welding consumables but not by the base metal. Resistance welding produced significantly lower TP and Mn exposures compared to other welding processes. Interestingly, exposures to TP had not changed over the 40 years of observation, while those of Mn showed (non-significant) reductions of 3.6% year(-1). After controlling for fixed effects, variance components between worksites and between-individual workers within a worksite were reduced by 89 and 57% for TP and 75 and 63% for Mn, respectively. The within-worker variation (sum of intraday and interday variance components) of Mn exposure was three times higher than that of TP exposure. The estimated probabilities of exceeding occupational exposure limits were very high (generally much >10%) for both agents.

CONCLUSIONS

Welding exposures to TP and Mn vary considerably across the world and across occupational groups. Exposures to both contaminants have been and continue to be unacceptably high in most sectors of industry. Because exposures to the two agents have different sources and characteristics, separate control strategies should be considered to reduce welders' exposures to TP and Mn.

Mapping particulate matter at the body weld department in an automobile assembly plant

A respiratory health survey conducted in an assembly plant in 2000-2001 found that welders had elevated rates of self-reported respiratory symptoms compared with painters and assembly workers. Subsequently, the ventilation system was improved at the body weld department. In a follow-up study, particle spatial distributions were analyzed, following a mapping protocol developed specifically for this workplace, to evaluate the effectiveness of the changes. Significant temporal and spatial variations were observed. Temporal variation during a shift was monitored with over-shift stationary sampling at fixed locations. Spatial variation was evaluated with 1-min time-weighted average particle concentrations measured throughout the process areas (212 locations). The arithmetic spatial mean across 212 locations for the respirable particles varied from 305 microg/m(3) to 501 microg/m(3) on 6 sampled days, with a standard deviation of 71 microg/m(3), indicating that the difference between before and after countermeasures must be at least 191 microg/m(3) to be considered statistically significant at the given sample sizes. The available data were not sufficient to evaluate the reduction of the particle concentrations after the countermeasures. The map of particle mass concentration revealed several high concentration areas, requiring further investigation and potentially higher level of controls. Resistance welding needed to be effectively controlled, as it could be the major particle emitting sources in the facility. The map of submicrometer (0.014 microm to 1.0 microm) particle count concentration presented different patterns from that of respirable particle mass concentration, indicating that the submicrometer particles tended to be more evenly distributed over the process areas. Workers not in proximity to intensive welding operations might be exposed to fine particles at levels higher than had traditionally been thought. Mapping was demonstrated to be an effective method to assess particle spatial distributions. A well-designed sampling protocol is critical to achieving the specific aims of a mapping study.

Personal exposure to metal fume, NO2, and O3 among production welders and non-welders

The objective of this study was to characterize personal exposures to welding-related metals and gases for production welders and non-welders in a large manufacturing facility. Welding fume metals and irritant gases nitrogen dioxide (NO(2)) and ozone (O(3)) were sampled for thirty-eight workers. Personal exposure air samples for welding fume metals were collected on 37 mm open face cassettes and nitrogen dioxide and ozone exposure samples were collected with diffusive passive samplers. Samples were analyzed for metals using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and welding fume metal exposure concentrations were defined as the sum of welding-related metals mass per volume of air sampled. Welding fume metal exposures were highly variable among similar types of welding while NO(2) and O(3) exposure were less variable. Welding fume metal exposures were significantly higher 474 μg/m(3) for welders than non-welders 60 μg/m(3) (p=0.001). Welders were exposed to higher concentrations of NO(2) and O(3) than non-welders but the differences were not statistically significant. Welding fume metal exposure concentrations for welders performing gas metal arc welding (GMAW) and shielded metal arc welding (SMAW) were higher than welders performing gas tungsten arc welding (GTAW). Non-welders experienced exposures similar to GTAW welders despite a curtain wall barrier separating welding and non-welding work areas.

Flow cytometric analysis of the oxidative status in human peripheral blood mononuclear cells of workers exposed to welding fumes

Flow cytometry is a simple analytical technique that identifies, counts, and characterizes cells. The oxidative status of cells is influenced by many exogenous sources, such as occupational exposure to welding fumes. This study evaluated flow cytometry as a method to determine the oxidative status of male welders (n = 15) occupationally exposed to welding fumes. Flow cytometric analysis of reactive oxygen species (ROS) was carried out in peripheral blood mononuclear cells (PBMC) by using the probe 2, 7-dichlorodihydrofluorescein diacetate (DCFH-DA). Lipid peroxidation was measured by the decrease of fluor-DHPE fluorescence and intracellular glutathione (GSH) levels by using mercury orange. All of the parameters were also observed under a confocal microscope. The oxidative stress ratio was calculated from the oxidative damage and the antioxidant capacity to give an accurate account of the cellular oxidative status. ROS and lipid peroxidation levels were elevated by approximately 87% and approximately 96%, respectively, and GSH levels lowered approximately 96% in PBMC of workers exposed to welding fumes compared with non-exposed controls. The oxidative stress ratio was significantly higher (p < 0.001) in the exposed group. Flow cytometry can be useful for the measurement of cellular oxidative stress in somatic cells of workers exposed to welding fumes and other occupational settings. Calculating an oxidative stress index may be useful in predicting disease outcomes and whether preventative control measures are efficient.

A systematic review of occupational exposure to particulate matter and cardiovascular disease

Exposure to ambient particulate air pollution is a recognized risk factor for cardiovascular disease; however the link between occupational particulate exposures and adverse cardiovascular events is less clear. We conducted a systematic review, including meta-analysis where appropriate, of the epidemiologic association between occupational exposure to particulate matter and cardiovascular disease. Out of 697 articles meeting our initial criteria, 37 articles published from January 1990 to April 2009 (12 mortality; 5 morbidity; and 20 intermediate cardiovascular endpoints) were included. Results suggest a possible association between occupational particulate exposures and ischemic heart disease (IHD) mortality as well as non-fatal myocardial infarction (MI), and stronger evidence of associations with heart rate variability and systemic inflammation, potential intermediates between occupational PM exposure and IHD. In meta-analysis of mortality studies, a significant increase in IHD was observed (meta-IRR = 1.16; 95% CI: 1.06–1.26), however these data were limited by lack of adequate control for smoking and other potential confounders. Further research is needed to better clarify the magnitude of the potential risk of the development and aggravation of IHD associated with short and long-term occupational particulate exposures and to clarify the clinical significance of acute and chronic changes in intermediate cardiovascular outcomes.

Biological effect markers in exhaled breath condensate and biomonitoring in welders: impact of smoking and protection equipment

PURPOSE

The objective of this study was to investigate the effect of welding as well as the impact of smoking and protection measures on biological effect markers in exhaled breath condensate. Additionally, biomonitoring of chromium, aluminium and nickel in urine was performed to quantify internal exposure.

METHODS

Exhaled breath condensate (EBC) and urine samples of 45 male welders and 24 male non-exposed control subjects were collected on Friday pre-shift and after 8 h of work post-shift. In EBC, biological effect markers such as malondialdehyde, nitrite, nitrate, 3-nitrotyrosine, tyrosine, hydroxyproline, proline, H(2)O(2) and pH-value were measured while aluminium, nickel, and chromium were measured in the urine samples.

RESULTS

Although internal exposure to aluminium, nickel and chromium in this study was low, welders showed significantly increased concentrations of all these parameters at baseline compared to non-exposed controls. Moreover, welders had higher nitrate concentrations in EBC at baseline and after shift. Nitrate concentration was considerably lower after shift if personal protection equipment was used. H(2)O(2) was increased only when subjects smoked during shift.

CONCLUSION

It has been shown that welding-associated long-term and short-term health effects could be detected in a population of welders. The results also showed that using personal protection equipment is of high importance and H(2)O(2) may be an effect marker associated with smoking rather than with welding fumes, while nitrate in EBC seems to be sensitive to welding fume exposure.

Individual exposure to particulate matter and the short-term arrhythmic and autonomic profiles in patients with myocardial infarction

AIMS

Epidemiological studies show that peak exposure to air pollution is associated with increased morbidity and mortality from cardiovascular events. Panel and controlled exposure studies show that particulate matter (PM) may influence the parasympathetic regulation of the heart. The aim of this study was to concurrently measure individual exposure to PM of various sizes, heart rate variability (HRV), and electrical instability in patients with myocardial infarction.

METHODS AND RESULTS

Personal exposures to PM(10), PM(2.5), and PM(0.25) was measured over 24 h in 39 patients (36 males, 3 females; mean age 60.3 years) with prior myocardial infarction (>6 months). Simultaneously, a 24 h ECG was recorded and then analysed for HRV and ventricular arrhythmias. Breath condensate and blood samples also were collected at the end of monitoring to measure several indexes of inflammation. Negative correlation was found between HRV and exposure to PM(0.25) in a group of patients not taking beta-blockers. More severe ventricular arrhythmias were observed at the highest concentrations of PM(10) and PM(2.5). Indexes of inflammation in either breath condensate or blood did not correlate with PM exposures.

CONCLUSION

Our study shows that exposure to ultrafine particles is associated with autonomic dysregulation in selected patients with myocardial infarction. More severe arrhythmias occur at the highest exposures to larger particles. Nevertheless, the underlying mechanisms remain hypothetical because inflammation may be evoked by PM or be related to the disease itself.

Involvement of sensory nerves and TRPV1 receptors in the rat airway inflammatory response to two environment pollutants: diesel exhaust particles (DEP) and 1,2-naphthoquinone (1,2-NQ)

The environmental chemical 1,2-naphthoquinone (1,2-NQ) is implicated in the exacerbation of airways diseases induced by exposure to diesel exhaust particles (DEP), which involves a neurogenic-mediated mechanism. Plasma extravasation in trachea, main bronchus and lung was measured as the local (125)I-bovine albumin accumulation. RT-PCR quantification of TRPV1 and tachykinin (NK(1) and NK(2)) receptor gene expression were investigated in main bronchus. Intratracheal injection of DEP (1 and 5 mg/kg) or 1,2-NQ (35 and 100 nmol/kg) caused oedema in trachea and bronchus. 1,2-NQ markedly increased the DEP-induced responses in the rat airways in an additive rather than synergistic manner. This effect that was significantly reduced by L-732,138, an NK(1) receptor antagonist, and in a lesser extent by SR48968, an NK(2) antagonist. Neonatal capsaicin treatment also markedly reduced DEP and 1,2-NQ-induced oedema. Exposure to pollutants increased the TRPV1, NK(1) and NK(2) receptors gene expression in bronchus, an effect was partially suppressed by capsaicin treatment. In conclusion, our results are consistent with the hypothesis that DEP-induced airways oedema is highly influenced by increased ambient levels of 1,2-NQ and takes place by neurogenic mechanisms involving up-regulation of TRPV1 and tachykinin receptors.

Spirometry, impulse oscillometry and capnovolumetry in welders and healthy male subjects

BACKGROUND

Welding processes emit fine and ultrafine aerosol particles which are potentially harmful to the lungs of welders. In the past, changes in lung function were mostly determined by conventional spirometry. In this study spirometry was combined with new techniques such as Impulse Oscillometry (IOS) and Capnovolumetry (CVS) in order to assess welding associated changes in lung function.

METHODS

45 Male welders and 24 non-welders were investigated at two time points: before work shift (baseline) and after work shift.

RESULTS

At baseline there were no differences between both study populations in spirometric, IOS, and CVS parameters. However, parameters of the flow-volume curve decreased with increasing long-term welding fume exposure (welding years). Airway resistances measured by IOS increased with welding years. IOS central airway resistance and several parameters of CVS increased during the work shift indicating airway narrowing and more inhomogeneous ventilation.

CONCLUSIONS

In this study it has been shown that welding associated long-term and short-term effects could be detected in a population of welders, although exposure conditions were quite heterogeneous. The parameters of IOS and Capnovolumetry showed effects even more pronounced than conventional lung function parameters. Thus, these techniques may be considered as an additional tool for occupational medicine research.

Prospective study of metal fume-induced responses of global gene expression profiling in whole blood

Metal particulate inhalation causes pulmonary and cardiovascular diseases. Our previous results showed that systemic responses to short-term occupational welding-fume exposure could be assessed by microarray analyses in whole-blood total RNA sampled before and after exposure. To expand our understanding of the duration of particulate-induced gene expression changes, we conducted a study using a similar population 1 yr after the original study and extended our observations in the postexposure period. We recruited 15 individuals with welding fume exposure and 7 nonexposed individuals. Thirteen of the 22 individuals (9 in exposed group and 4 in nonexposed group) had been monitored in the previous study. Whole-blood total RNA was analyzed at 3 time points, including baseline, immediately following exposure (approximately 5 h after baseline), and 24 h after baseline, using cDNA microarray technology. We replicated the patterns of Gene Ontology (GO) terms associated with response to stimulus, cell death, phosphorus metabolism, localization, and regulation of biological processes significantly enriched with altered genes in the nonsmoking exposed group. Most of the identified genes had opposite expression changes between the exposure and postexposure periods in nonsmoking welders. In addition, we found dose-dependent patterns that were affected by smoking status. In conclusion, short-term occupational exposure to metal particulates causes systemic responses in the peripheral blood. Furthermore, the acute particulate-induced effects on gene expression profiling were transient in nonsmoking welders, with most effects diminishing within 19 h following exposure.

Acute changes in vascular function among welders exposed to metal-rich particulate matter

BACKGROUND

Although welding fume exposure is associated with adverse cardiovascular outcomes, the mechanisms remain unclear. To investigate the role of vascular function, we assessed levels of the augmentation index (a correlate of arterial stiffness) after short-term exposure to welding-derived fine particulate matter (PM2.5).

METHODS

In a panel study, we monitored 26 male welders over 24 hours on a welding day (n = 25), a non-welding day (n = 15), or both (n = 14). Augmentation index (expressed as a percent) was obtained in the morning before exposure (baseline) and after exposure in the afternoon and the following morning. Personal PM2.5 exposure was measured over 6 hours of welding or an equivalent non-welding period. We used linear mixed models adjusting for baseline augmentation index, smoking, age, and time to evaluate the effects of welding (binary) and PM2.5 (continuous) on augmentation index levels. We also assessed modification by welding exposure the day before monitoring (binary).

RESULTS

Welding was associated with a 2.8% increase in afternoon augmentation index (95% confidence interval = -1.4 to 7.0) and a 2.4% decrease (-6.9 to 2.2) in next-morning augmentation index. Additional exposure the day prior to monitoring was associated with a greater afternoon increase (5.1%; 0.8 to 9.5). Using PM2.5 concentration, a positive association was observed in the afternoon and an inverse association the next morning; results differed by previous day's welding status after excluding outliers.

CONCLUSIONS

Subsequent to welding fume exposure, there is an increase in afternoon augmentation index and a decrease in next-morning augmentation index, with greater changes after consecutive days of exposure. These results suggest that exposure to the PM2.5 component of welding fume elicits acute adverse vascular responses.

Cardiovascular risk factors and signs of subclinical atherosclerosis in the Heinz Nixdorf Recall Study

INTRODUCTION

Modern investigation modalities allow markers of atherosclerosis to be detected at a subclinical stage. The aim of the study was to analyze the prevalence of these markers in relation to traditional risk factors.

METHODS

The population based study included 4814 participants, aged 45 to 75 years, with a response rate of 55.8% of those contacted. The patients' history, psychosocial and environmental risk factors were assessed.

RESULTS

The prevalence of obesity was 26.2% in men and 28.1% in women, 26% of men and 21% of women were smokers. Hypertension was found in 46% of men and 31% of women, diabetes in 9.3% of men and 6.3% of women. Markers of subclinical peripheral arterial disease were found in 6.4% of men and 5.1% of women, of subclinical carotid artery disease in 43.2% and 30.7%, and of subclinical coronary artery calcification in 82.3% and 55.2%, respectively. The prevalence of coronary calcification measured using an Agatston Score >100 was in 40% in men and 15% in women, using a score >400, 16.8% and 4.5%, respectively.

DISCUSSION

A high prevalence of subclinical atherosclerosis was found in the older population. The follow-up period will demonstrate whether the detection of markers of subclinical atherosclerosis will improve risk stratification beyond that offered by traditional risk factors.

Short-term effects of particulate matter: an inflammatory mechanism?

"Would you tell me please, which way I ought to go from here," asked Alice. "That depends a good deal on where you want to go to," said the cat. (Lewis Carroll, Alice's Adventures in Wonderland) A large number of epidemiological studies show positive correlations between increasing levels of particulate matter (PM) in urban air and short-term morbidity and mortality for diverse acute cardiopulmonary diseases. Brought about by PM increments, inflammation is thought to exacerbate preexisting inflammatory diseases. Experimental evidence suggests a hierarchical oxidative stress model, in which a weakened antioxidant defense, as observed in disease or induced by inhaled particles, increases the PM ability to cause lung inflammation, accounting for exacerbations that occur in asthmatics and in patients with chronic obstructive lung disease. The role of PM-induced inflammation leading to acute cardiovascular events such as arrhythmia, heart failure, and myocardial infarction is more speculative. There is neither clear-cut evidence in humans that inhaled PM could get as far as blood circulation nor that proinflammatory mediators are significantly released from inflamed lung tissues, nor that blood coagulability is critically altered. As a whole, data in humans indicate that short-term inflammatory responses to PM are not always detected; they are usually mild and loosely correlated with functional changes. Among these studies, the diversity of PM characteristics, dose metrics, and endpoints hampers a clear discerning of inflammatory mechanism(s). Thus, the question arises as to whether inflammation represents the mechanism of acute cardiopulmonary PM toxicities in susceptible individuals, or rather an event that may coexist with other relevant mechanism(s). This review article discusses the evidence in humans linking short-term PM increments to inflammation and to exacerbations of cardiopulmonary diseases. Although there is a large amount of data available, there still remains a gulf between the number of epidemiological and panel studies and that of controlled exposures. Research on controlled exposure needs expanding, so that the results of time-series and panel studies will be better understood and short-term standards for human exposure may be more confidently allocated.

Short-Term Effects of Particulate Air Pollution on Male Smokers and Never-Smokers

BACKGROUND

Numerous studies have shown that ambient air pollution and smoking are both associated with increased mortality, but until now there has been little evidence as to whether the effects of these 2 factors combined are greater than the sum of their individual effects. We assessed whether smokers are subject to additional mortality risk from air pollution relative to never-smokers.

METHODS

This study included 10,833 Chinese men in Hong Kong who died at the age of 30 or above during the period 1 January to 31 December 1998. Relatives who registered for deceased persons were interviewed about the deceased's smoking history and other personal lifestyle factors about 10 years before death. Poisson regression for daily number of deaths was fitted to estimate excess risks per 10 microg/m increase in particulate matter with aerodynamic diameter <10 microm (PM10) in male smokers and never-smokers in stratified data, and additional excess risk for smokers relative to never-smokers in combined data.

RESULTS

In smokers there was a significant excess risk associated with PM10 for all natural causes and cardio-respiratory diseases for men age 30 years or older and men 65 or older. For all natural causes, greater excess risk associated with PM10 was observed for smokers relative to never-smokers: 1.9% (95% confidence interval = 0.3% to 3.6%) in men age 30 and older and 2.3% (0.4% to 4.3%) in those age 65 and older.

CONCLUSIONS

Ambient particulate air pollution is associated with greater excess mortality in male smokers compared with never-smokers.

Heart rate variability, hemostatic and acute inflammatory blood parameters in healthy adults after short-term exposure to welding fume

The present study aimed to investigate, whether short-term experimental exposure to high levels of welding fumes would be capable of exerting acute effects in healthy subjects. Specifically, we assessed cardiovascular function in terms of heart rate variability (HRV) as well as the concentrations of inflammatory mediators and hemostatic proteins in blood as outcome measures. Twenty subjects without a history of airway and cardiovascular diseases were exposed to either control air or welding fume for 1 h on 2 separate days under standardized conditions. The median concentration of the alveolar particle fraction during welding was 3.5 mg/m(3 )(quartiles: 1.4-6.3 mg/m(3); range 1.0-25.3 mg/m(3)). Five hours later a panel of clinical assessments was performed, including HRV measurement and drawing of blood samples. There were no changes in symptom ratings or lung function after welding fume exposure. Exposures did also not differ regarding effects on time- and frequency-domain parameters of HRV. Similarly, blood leukocyte numbers, cell differentials and the blood levels of fibrinogen, C-reactive protein, antithrombin III, factor VIII, von Willebrand factor, ristocetin cofactor, sICAM-1, tumor necrosis factor alpha, interleukin 6, interleukin 8 and epithelial neutrophil activating peptide 78 were not altered by welding fume inhalation. However, there was a significant fall in the level of endothelin-1 (P < 0.01). In conclusion, the data did not indicate effects of clinical significance of a short-term high-level exposure to welding fumes on HRV or a set of blood hemostatic and acute inflammatory parameters in healthy subjects. The small but statistically significant effect on endothelin levels demonstrated that measurable effects could be elicited even in these individuals. Overall, welding fumes are not likely to exert acute cardiovascular effects in healthy individuals.

pH Increase Observed in Exhaled Breath Condensate from Welding Fume Exposure

OBJECTIVES

We sought to investigate changes in exhaled breath condensate (EBC) pH in healthy workers exposed to welding fumes.

METHODS

Fourteen exposed participants (median age 39 years, 5 smokers) and 8 nonexposed controls (median age 44 years, 1 smoker) were monitored at an apprentice welding school. Exposure to fine particulate matter less than 2.5 microm (PM2.5) was assessed using cyclone samplers. EBC samples were collected at baseline and at the end of the work shift. EBC samples were deaerated using argon and pH values were measured using standard pH microelectrodes.

RESULTS

Mean +/- SEM PM2.5 levels were 1.17 +/- 0.18 mg/m for exposed subjects and 0.03 +/- 0.01 mg/m for controls. Baseline median (range) EBC pH values for the control and exposed group were similar (P = 0.86), 7.21 (4.91 to 8.26), and 7.39 (4.85 to 7.79), respectively. The exposed subjects had a small-but-marginally significant (P = 0.07) pre- to post-work shift increase in pH of 0.28, whereas the control group showed a minimal increase of only 0.03 (P = 0.56). Compared with the control group, the exposed group had a median cross-shift pH increase of 0.25 (P = 0.49).

CONCLUSIONS

The aerosolized fine particulate matter contained in metal fumes may be associated with an acute increase in EBC pH values. Further study is necessary to investigate the acute rise in EBC pH after acute exposure to welding fume.

Induction of proinflammatory cytokines and C-reactive protein in human macrophage cell line U937 exposed to air pollution particulates

Exposure to particulate matter air pollution causes inflammatory responses and is associated with the progression of atherosclerosis and increased cardiovascular mortality. Macrophages play a key role in atherogenesis by releasing proinflammatory cytokines and forming foam cells in subendothelial lesions. The present study quantified the inflammatory response in a human macrophage cell line (U937) after exposure to an ambient particulate sample from urban dust (UDP) and a diesel exhaust particulate (DEP). The effect of native UDP and DEP was compared with their corresponding organic extracts (OE-UDP/OE-DEP) and stripped particles (sUDP/sDEP) to clarify their respective roles. Exposure to OE-UDP, OE-DEP, UDP, DEP, and 2,3,7,8-tetrachlorodibenzo-p-dioxin led to a greater increase of interleukin (IL)-8, tumor necrosis factor-alpha, and cyclooxygenase-2 mRNA expression than did the stripped particles, whereas sUDP, sDEP, UDP, and DEP led to a greater production of C-reactive protein and IL-6 mRNA. The particles and the organic extract-induced expression of cyclooxygenase-2 and cytochrome P450 (CYP)1a1 was significantly suppressed by co-treatment with an aryl hydrocarbon receptor (AhR) antagonist, indicating that these effects are mainly mediated by the organic components, which can activate the AhR and CYP1a1. In contrast, the induction of C-reactive protein and IL-6 seems to be a particle-related effect that is AhR independent. The inflammatory response induced by particulate matter was associated with a subsequent increase of cholesterol accumulation, a hallmark of foam cells. Together, these data illustrate the interaction between particulate matter and the inflammatory response as well as the formation of cholesterol-accumulating foam cells, which are early markers of cardiovascular disease.