Physicochemical properties of air discharge-generated manganese oxide nanoparticles: comparison to welding fumes

Abstract

Exposures to high doses of manganese (Mn) via inhalation, dermal contact or direct consumption can cause adverse health effects. Welding fumes are a major source of manganese containing nanoparticles in occupational settings. Understanding the physicochemical properties of manganese-containing nanoparticles can be a first step in understanding their toxic potential following exposure. In particular, here we compare the size, morphology and Mn oxidation states of Mn oxide nanoparticles generated in the laboratory by arc discharge to those from welding collected in heavy vehicle manufacturing. Fresh nanoparticles collected at the exit of the spark discharge generation chamber consisted of individual or small aggregates of primary particles. These nanoparticles were allowed to age in a chamber to form chain-like aggregates of primary particles with morphologies very similar to welding fumes. The primary particles were a mixture of hausmannite (Mn3O4), bixbyite (Mn2O3) and manganosite (MnO) phases, whereas aged samples revealed a more amorphous structure. Both Mn2+ and Mn3+, as in double valence stoichiometry present in Mn3O4, and Mn3+, as in Mn2O3 and MnOOH, were detected by X-ray photoelectron spectroscopy on the surface of the nanoparticles in the laboratory nanoparticles and welding fumes. Dissolution studies conducted for these two Mn samples (aged and fresh fume) reveal different release kinetics of Mn ions in artificial lysosomal fluid (pH 4.5) and very limited dissolution in Gamble’s solution (pH 7.4). Taken together, these data suggest several important considerations for understanding the health effects of welding fumes. First, the method of particle generation affects the crystallinity and phase of the oxide. Second, welding fumes consist of multiple oxidation states whether they are amorphous or crystalline or occur as isolated nanoparticles or agglomerates. Third, although the dissolution behavior depends on conditions used for nanoparticle generation, the dissolution of Mn oxide nanoparticles in the lysosome may promote Mn ions translocation into various organs causing toxic effects.

Size, composition, morphology, and health implications of airborne incidental metal-containing nanoparticles

“…Previously, the generation of Fe and Mn nanoparticles was simulated to have a close model to characterize the materials and their behavior under contact with biological solutions. (65,68) However, from this study, it is concluded that new models that include heterogeneous agglomerates of incidental nanoparticles (Fe-Mn-Cu and Fe-Mn-Zn) with both architectures are required to better understand the health implications that these incidental nanoparticles will have.…”

“…(40) This can have a significant effect on the inflammatory responses that the agglomerates will generate in the lung as each oxide dissolves at different rates. (64,65) In addition, the transport of the same INPs to different parts of the respiratory tract may generate different health effects. (66) For example, ZnO and Cu/CuO nanoparticles have shown to dissolve in the lung mostly by macrophage action, (64,67) but there is no indication that dissolution will occur if transported directly to the brain by the olfactory system.…”

Análisis de la microestructura de humos de soldadura de aceros de bajo y medio contenido de carbon

“…However, previous studies have experimentally showed that metals and heavy metals emitted by welding fumes still pollute the environment. • Therefore, it can be clearly stated that these materials are vented into the atmosphere and threaten the environment and human health because the fume produced during the welding process contains many different oxides and elements (Stockmann-Juvala et al, 2013;Stebounova et al, 2018;McCarrick, et al, 2019). • The data obtained in this study provide important information for understanding the effects of welding fumes on health and environment.…”

“…Since welding fumes consist of ultra-fine particles, these structures were essentially shapeless. The structures of the phases obtained from the XRD analysis given in Table 1 were composed of different crystal lattice structures as reported in previous studies (Ehrman et al, 1999;Stebounova et al, 2018). During the condensation of these particles, separate molecules may get together to form different phases in a single structure.…”

“…Previous works have reported some specific chemical composition of welding (Ehrman et al, 1999;Jenkins and Eagar, 2005a;Jenkins and Eagar, 2005b;Sowards et al, 2010;Golbabaei and Khadem, 2015;Stebounova et al, 2018). However, there is still need of a study involving comprehensive analysis of chemical composition of welding fume in order to have better understanding on possible adverse health effects, and have create better preventive and safety strategies.…”