Behavior of aluminum in aluminum welders and manufacturers of aluminum sulfate—impact on biological monitoring

Abstract

Riihimäki V, Valkonen S, Engström B, Tossavainen A, Mutanen P, Aitio A. Behavior of aluminum in aluminum welders and manufacturers of aluminum sulfate-impact on biological monitoring. Scand J Work Environ Health 2008;34(6):451-462. ObjectivesThe suitability of determining aluminum in serum or urine as a form of biological monitoring was critically assessed.Methods Airborne and internal aluminum exposure was assessed for 12 aluminum welders in a shipyard and 5 manufacturers of aluminum sulfate. Particles were characterized with X-ray diffraction and scanning electron microscopy. Aluminum in air and biological samples was analyzed using electrothermal atomic absorption spectrometry. Basic toxicokinetic features were inferred from the data. ResultsThe mean 8-hour time-weighted average concentration of aluminum was 1.1 (range 0.008-6.1) mg/m 3 for the shipyard and 0.13 (range 0.02-0.5) mg/m 3 for the aluminum sulfate plant. Welding fume contained aluminum oxide particles <0.1 µm in diameter and their agglomerates, whereas bauxite and aluminum sulfate particles ranged from 1 to 10 µm in diameter. The shipyard welders' mean postshift serum and urinary concentrations of aluminum (S-Al and U-Al, respectively) were 0.22 and 3.4 µmol/l, respectively, and the aluminum sulfate workers' corresponding values were 0.13 and 0.58 µmol/l. Between two shifts, the welders' S-Al concentration decreased by about 50% (P<0.01), but their U-Al concentration did not change (P=0.64). No corresponding temporal changes occurred among the aluminum sulfate workers. After aluminum welding at the shipyard had ceased, the median S-Al concentration decreased by about 50% (P=0.007) within a year, but there was no change (P=0.75) in the corresponding U-Al concentration.Conclusions About 1% of aluminum in welding fume appears to be rapidly absorbed from the lungs, whereas an undetermined fraction is retained and forms a lung burden. A higher fractional absorption of aluminum seems possible for aluminum sulfate workers without evidence of a lung burden. After rapid absorption, aluminum is slowly mobilized from the lung burden and dominates the S-Al and U-Al concentrations of aluminum welders. For kinetic reasons, S-Al or U-Al concentrations cannot be used to estimate the accumulation of aluminum in the target organs of toxicity. However, using U-Al analysis to monitor aluminum welders' lung burden seems practical.

Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts

“…Plasma collected from volunteers with no known Al exposure generally contains ≤ 2.7 μg/L (with an upper normal limit of ~6 μg/L), serum generally contains up to approximately 3 μg/L and urine generally contains approximately 1–9 μg/L. The Zeager et al (2012) conclusion is not consistent with others who have used blood and urinary Al to monitor HD patients (Pei et al 1992, 1995), Al welders and other industrial workers (DFG 2007, Riihimaki et al 2008, Riihimaki and Aitio 2012). …”

Biological monitoring of occupational exposure to dust among aluminium foundry workers

“…In the study of Hull & Abraham on subjects exposed to welding fumes, the results showed that most of the particles were accumulated and the average diameter of the AL particles was 0.34 μm and there were also the singlet particles as small as 10 nm in diameter [27]. The toxicokinetic of AL in human by inhalation, which is the main route of exposure in occupational workplaces, has not received much attention [28]. It may be difficult to estimate the actual body burden due to the reabsorption of inhaled AL in the lung [9].…”

Metal load assessment in patient pulmonary lavages: towards a comprehensive mineralogical analysis including the nano-sized fraction

“…Thus, they developed a method to collect, recover, and analyze Cr, Mn and Ni nanoparticles (metals that have been linked with severe health outcomes) generated during welding, separately from larger particles. Similarly, Riihimäki et al (Riihimäki et al, 2008) highlighted the impact of the particle size on toxicity: while aluminum metal and aluminum oxide are practically insoluble in water and are thus presumably poorly absorbed into living organisms, oxidized aluminum, contained in ultrafine particles, behaves differently, since some aluminum of the welding fume is rapidly taken up by the welder's lungs. It argues once again for the study of the finest fraction separately from its larger counterpart.…”