Behavior of aluminum in aluminum welders and manufacturers of aluminum sulfate--impact on biological monitoring.
OBJECTIVE
The 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.


RESULTS
The 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 microm in diameter and their agglomerates, whereas bauxite and aluminum sulfate particles ranged from 1 to 10 microm 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 micromol/l, respectively, and the aluminum sulfate workers' corresponding values were 0.13 and 0.58 micromol/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.
Riihimäki
Vesa
V
Good Practices and Competence, Statistical Services, Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, FI-00250 Helsinki, Finland. vesa.riihimaki@ttl.fi
Valkonen
Sinikka
S
Engström
Bernt
B
Tossavainen
Antti
A
Mutanen
Pertti
P
Aitio
Antero
A
D000328:Adult; D000395:Air Pollutants, Occupational / Q000032:analysis* / Q000097:blood / Q000652:urine; D000534:Alum Compounds / Q000032:analysis / Q000378:metabolism*; D000535:Aluminum / Q000032:analysis* / Q000097:blood / Q000652:urine; D004391:Dust / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D005260:Female; D005387:Finland; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D016273:Occupational Exposure / Q000032:analysis; D012767:Ships; D013054:Spectrophotometry, Atomic; D014896:Welding; D014961:X-Ray Diffraction
D000395:Air Pollutants, Occupational; D000534:Alum Compounds; D004391:Dust; C041524:aluminum sulfate; D000535:Aluminum