Occupational Exposure to Welding Fume among Welders: Alterations of Manganese, Iron, Zinc, Copper, and Lead in Body Fluids and the Oxidative Stress Status

Abstract

Welders in this study were selected from a vehicle manufacturer; control subjects were from a nearby food factory. Airborne manganese levels in the breathing zones of welders and controls were 1.45 ± SD1.08 mg/m 3 and 0.11 ± 0.07 μg/m 3 , respectively. Serum levels of manganese and iron in welders were 4.3-fold and 1.9-fold, respectively, higher than those of controls. Blood lead concentrations in welders increased 2.5-fold, whereas serum zinc levels decreased 1.2-fold, in comparison with controls. Linear regression revealed the lack of associations between blood levels of five metals and welder's age. Furthermore, welders had erythrocytic superoxide dismutase activity and serum malondialdehyde levels 24% less and 78% higher, respectively, than those of controls. These findings suggest that occupational exposure to welding fumes among welders disturbs the homeostasis of trace elements in systemic circulation and induces oxidative stress.The welding fume generated during the welding process possesses at least 13 metals, including manganese (Mn), beryllium (Be), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), mercury (Hg), molybdenum (Mo), nickel (Ni), zinc (Zn), antimony (Sb), and vanadium (V). 1 Welders are known to be at risk, particularly for chronic exposure to airborne manganese, which is one of the major coating materials in welding products (eg, bars and wires). [2][3][4][5][6] A recent study even suggests that exposure to manganese during welding may be a risk factor for the etiology of Parkinson's disease among the career welders. 7 Although limited studies have documented airborne manganese levels during welding, the question as to how low-level, long-term exposure to manganese or welding fume may affect blood levels of trace metals is unanswered. However, altered systemic homeostasis of iron and manganese is known to be associated with neurodegenerative disorders. 8 Manganese-induced neurological lesions are reportedly located in the globus pallidus and striatum of the basal ganglia. The pallidus and striatum display a marked decrease in myelinated nerve fibers, accompanied by depletion of striatal dopamine. [11][12][13][14] The mechanism whereby manganese induces neurodegenerative damage remains elusive. Nonetheless, several recent reports have suggested that manganese neurotoxicity may be associated with its interaction with other essential trace elements, including iron, 10,13,15,16 zinc, 17 copper, 17 and aluminum. 13,15,18 Particularly regarding manganese-induced neurotoxicity, studies have shown that chronic exposure to manganese appears to be associated with altered iron concentrations in blood as well as in the cerebrospinal fluid, presumably the result of Mn-Fe interaction at certain [Fe-S]-containing proteins, which regulate the homeostasis of iron. 10,16,[19][20][21] The excess accumulation of iron in neurons may consequently produce cellular oxidative stress, leading to neuronal damage.Superoxide dismutase (SOD), a cytoplasmic enzyme, catalyzes the react...

Brain magnetic resonance imaging and manganese concentrations in red blood cells of smelting workers: Search for biomarkers of manganese exposure

“…Determination of Mn concentrations in the whole blood, plasma, or serum has been used in our previous clinical and experimental animal studies (Li et al, 2004;Lu et al, 2005;Zheng et al, 1999). Since Mn is primarily intracellularly distributed (Crossgrove and Zheng, 2004), it was reasonable to hypothesize that Mn in the blood compartment may accumulate in the blood cells, and a direct assay of Mn in the RBC fraction may serve as a better indicator for Mn concentrations in the blood circulation.…”

“…Most studies prior to this work on MRI and Mn exposure were conducted on exposed welders (Josephs et al, 2005;Kim et al, 1999c;Nelson et al, 1993;Ono et al, 2002). Since the welding fumes generated during the welding process possesses at least 13 metals (Li et al, 2004), the exposure to multiple metals, notably iron (Fe), may complicate the exposure scenario for accurate assessment of Mn exposure. In addition, the welders' job assignments vary frequently between indoor and outdoor environments and amid open or closed compartments, bringing about the day-to-day variations in exposure conditions.…”

Assessment of occupational exposure to welding fumes by inductively coupled plasma‐mass spectroscopy and by the alkaline Comet assay

“…Many biomonitoring studies have measured metal concentrations in body fluids to assess exposure to welding fumes, and this assessment is often conducted using inductively coupled plasma-mass spectroscopy (ICP-MS) [Danadevi et al, 2004;Li et al, 2004]. As indicated above, biological endpoints, such as DNA damage, can be monitored by analysis of CA and SCE [Jelmert et al, 1995], micronuclei in either buccal cells [Danadevi et al, 2004] or lymphocytes [Medeiros et al, 2003], DNA-protein crosslinks [Costa et al, 1993], or unscheduled DNA synthesis [Knudsen et al, 1992].…”

Alteration of Serum Concentrations of Manganese, Iron, Ferritin, and Transferrin Receptor Following Exposure to Welding Fumes Among Career Welders

“…The differences between two means were analyzed by a standard, parametric ANOVA. A statistics software SPSS/PC+ for Windows (V. 10.0) was used in data analysis (Li et al, 2004).…”

“…Several lines of evidence suggest that manganese-induced neurotoxicities appear to be associated with altered iron (Fe) metabolism at both systemic and cellular levels (Chua and Morgan, 1996;Li et al, 2004;Malecki et al, 1999;Zheng and Zhao, 2001;Zheng et al, 1999). In vivo manganese exposure in animals appears to facilitate the influx of iron from the blood to the cerebral spinal fluid (CSF) .…”