Acute respiratory effects and biomarkers of inflammation due to welding-derived nanoparticle aggregates

Abstract

PurposeWelders are exposed to airborne particles from the welding environment and often develop symptoms work-related from the airways. A large fraction of the particles from welding are in the nano-size range. In this study we investigate if the welders’ airways are affected by exposure to particles derived from gas metal arc welding in mild steel in levels corresponding to a normal welding day.MethodIn an exposure chamber, 11 welders with and 10 welders without work-related symptoms from the lower airways and 11 non-welders without symptoms, were exposed to welding fumes (1 mg/m3) and to filtered air, respectively, in a double-blind manner. Symptoms from eyes and upper and lower airways and lung function were registered. Blood and nasal lavage (NL) were sampled before, immediately after and the morning after exposure for analysis of markers of oxidative stress. Exhaled breath condensate (EBC) for analysis of leukotriene B4 (LT-B4) was sampled before, during and immediately after exposure.ResultsNo adverse effects of welding exposure were found regarding symptoms and lung function. However, EBC LT-B4 decreased significantly in all participants after welding exposure compared to filtered air. NL IL-6 increased immediately after exposure in the two non-symptomatic groups and blood neutrophils tended to increase in the symptomatic welder group. The morning after, neutrophils and serum IL-8 had decreased in all three groups after welding exposure. Remarkably, the symptomatic welder group had a tenfold higher level of EBC LT-B4 compared to the two groups without symptoms.ConclusionDespite no clinical adverse effects at welding, changes in inflammatory markers may indicate subclinical effects even at exposure below the present Swedish threshold limit (8 h TWA respirable dust).

Comprehensive proteome analysis of nasal lavage samples after controlled exposure to welding nanoparticles shows an induced acute phase and a nuclear receptor, LXR/RXR, activation that influence the status of the extracellular matrix

“…In this study, we observed the effects on the proteome level in the nasal region after exposure to welding fumes. Proteins with changed levels were detected following welding fume particle exposure compared to filtered air, although neither clinical symptoms nor specific pro-inflammatory markers in nasal lavage were recorded in the study subjects [ 18 ]. This suggests that by applying a more comprehensive proteomic analysis, important biological information might still be gained even if no clinical symptoms can be recorded.…”

“…However, these suggestions have to be further studied because there is a possibility of leakage from the circulation as result of exposure-related tissue damage. A previous study [ 18 ] of a symptomatic welding group showed that they had an increasing trend of blood neutrophils after exposure and that they had a tenfold higher level of exhaled breath condensate leukotriene B4 compared to the other groups. Leukotrienes use lipid signaling to convey information order to regulate immune responses, and leukotriene B4 is involved in inflammation [ 54 ].…”

“…Six welders reported work-related nasal symptoms (runny nose, itching/sneezing) during the last month, and three welders showed a positive skin prick test for a standard panel of aeroallergens. Furthermore, lung function (FVC and FEV 1 as % of predicted) and methacholine test (PD 15 ) were carried out [ 18 ]. For the whole group the lung function was normal: FVC: 99 (72–114) and FEV 1 : 101 (66–132; % of predicted, median, min–max).…”

“…Elevated levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1, IL-6, and IL-8 have been observed after welding exposure [ 15 – 17 ]. It has also been shown that even at low exposure levels in a controlled human chamber study where no clinical symptoms were recorded, biomarkers of inflammation were still induced [ 18 ]. There is a need for a deeper understanding of the mechanisms involved in the responses induced by welding fume particle exposure, and the identification of proteins and pathways associated with welding fume particle exposure is an important step in this regard.…”

Nanotoxicology: The Need for a Human Touch?

“…Secondly, exposure to nanoparticle‐rich welding fumes (1 mg m −3 intermittently for 3 s every 20 min for 5.5 h) in a chamber setting led to mild increases in IL‐6 in the nasal lavages of welders without lower airways symptoms, whereas there were no significant changes in lung function or blood biomarkers. [ 104 ] To the best of our knowledge, we are aware of only a two sets of experiments that have performed inhalation exposures to a MNM of potentially greater toxicity (excluding combustion‐derived particle studies), both using zinc oxide nanoparticles. [ 105–108 ] Beckett et al.…”