Benjamin Gerhards

Single and Combined Exposure to Zinc- and Copper-Containing Welding Fumes Lead to Asymptomatic Systemic Inflammation.

Objective: Recently, it has been shown that exposure to welding fumes containing both zinc and copper leads to asymptomatic systemic inflammation in humans as shown by an increase of blood C-reactive protein. In the present study, it was investigated which metal is responsible for this effect. Methods: Fifteen healthy male subjects were exposed under controlled conditions to welding fumes containing either zinc, or copper, or copper and zinc. Results: For each exposure blood C-reactive protein increased. Conclusions: Copper- and zinc-containing welding fumes are able to induce systemic inflammation.

101 Biological effects of copper and zinc containing welding fumes after controlled exposure of humans

Introduction Copper and zinc containing welding fumes are suspected to induce inflammatory reactions, which, in humans, may result in metal fume fever. In a series of studies, early reactions of such welding fumes were investigated. Methods Exposures were performed in the Aachen Workplace Simulation Lab. 15 healthy male subjects were exposed for 6 hours to average welding fume mass concentrations up to 2.5 mg m-3. Welding fumes resulted from Metal-Inert-Gas brazing of zinc coated steel using copper welding wire or resistance spot welding of zinc-coated steel. Inflammatory markers were measured in the blood or in nasal secretions prior to exposure, directly after or 24–29 hours after exposure. Results The main results of these studies were: exposure to zinc and copper containing welding fumes lead to an asymptomatic inflammatory reaction as shown by an increase of blood C–reactive–Protein (CRP). Ultrafine resistance spot welding particles with similar composition and number concentration but lower mass concentration do not induce such reactions. Both, copper and zinc are individually able to induce such inflammation reactions. However, copper seems to have a higher potential for this induction. The inflammatory reaction is also reflected by an increase of Serum Amyloid A (SAA) and Interleukin 6 in the blood and by an increase of Interferon–λ and CRP in nasal secretions. Discussion Since increases of CRP, SAA, and IL-6 indicate an increased risk for cardiovascular disease, exposure to zinc and copper containing welding fumes may have to be considered for the prevention of work related cardiovascular disease. Future studies should investigate, if the observed inflammatory reaction persists after repeated exposure

Human nasal mucosal C-reactive protein responses after inhalation of ultrafine welding fume particles: positive correlation to systemic C-reactive protein responses

Abstract Exposures to occupationally relevant ultrafine, zinc- and copper-containing welding fumes cause inflammatory responses involving systemic IL-6, C-reactive protein (CRP) and serum amyloid A (SAA), all associated with elevated risk of cardiovascular events. We investigated whether the systemic response is preceded by nasal inflammatory reactions. Fifteen nonsmoking male subjects were exposed for 6 h under controlled conditions to zinc-/copper-containing welding fumes (at 2.5 mg/m3) or ambient air control in a randomized order. Nasal secretions were collected before and at 1, 3, 6, 10, and 29 h after exposure. Nasal levels of selected biomarkers were determined by electrochemiluminescent assays and related to their systemic levels. Nasal interferon-γ (IFN-γ) peaked significantly 1 h after start of exposure compared to baseline. Nasal CRP as well as SAA increased significantly at 10 and 29 h compared to baseline. Receiver operating characteristic (ROC) curve analysis for differentiating welding fume from control exposure was performed: The highest area under ROC curve (AUC) values were found for the CRP increases (10, 29 h versus 0 h): AUC = 0.83, and for IFN-γ increases (1 h versus 0 h): AUC = 0.92. Nasal and systemic changes of CRP at 29 h revealed a strong correlation (Spearman rank test: increases compared to baseline: r = 0.815, p = 0.0022; absolute levels: r = 0.9, p = 0.0002). In conclusion, short-term exposure to a zinc- and copper-containing welding fume causes significant increases of inflammatory mediators in nasal mucosal lining fluid. Therefore, measurement of nasal inflammatory mediators may provide a useful means for occupational surveillance of workers exposed to ultrafine metal fume particles.

The effects of zinc- and copper-containing welding fumes on murine, rat and human precision-cut lung slices

Recently, the pro-inflammatory effects of metal inert gas brazing welding fumes containing zinc and copper have been demonstrated in humans. Here, murine, rat and human precision cut lung slices (PCLS) were incubated in welding fume containing media with 0.1, 1, 10 and 100 μg/ml for 24 or 48 h. 24 h incubation were determined either by incubation for the total time or for only 6 h followed by a 18 h post-incubation phase. Cytotoxicity, proliferation and DNA repair rates, and cytokine levels were determined. Welding fume particle concentrations of 0.1 and 1 μg/ml showed no toxic effects on PCLS of all three species, while for 10 and 100 μg/ml a concentration-dependent toxicity occurred. Proliferation and DNA repair rates were reduced for all tested concentrations and incubation times. Additionally, the cytokine levels in the supernatants were markedly reduced, while after 6 h of exposure with 18 h of post-incubation time a trend towards increased cytokine levels occurred. PCLS are a reliable and feasible method to assess and offer a prediction of toxic effects of welding fume particles on human lungs. Rat PCLS showed similar responses compared to human PCLS and are suitable for further evaluation of toxic effects exerted by welding fume particles.

Laser beam welding of ultrahigh strength martensitic steels with active cooling

Recent steel developments create new possibilities for steel construction and lightweight design. The reason for this is the ultrahigh strength of particular steel grades. Fully martensitic steels like 22MnB5 or S1100 QL gain ultimate yield strengths of up to 1500 MPa. Therefore, those grades are predestined for crash relevant or highly loaded parts, and they gain increasing importance as construction materials. As promising as the martensitic ultrahigh strength steels are as construction materials, there are some issues when it comes to joining. The heat input into the material harms the costly adjusted material properties. Thus, each welding process reduces the strength in the heat-affected zone considerably. The key to reduce the drop in strength is to conduct the welding heat out of the work piece. The quicker the heat is conducted the lesser it can harm the material properties. Therefore, it is vital to select an active cooling device capable of conducting a large amount of heat out of the work piece...