Aluminum - Toxicology of Metals - page 338

convulsions (Hantson et al ., 1994) and a third from sep-
tic complications (Reusche et al ., 2001).
Intravesical alum instillation is a treatment for hem-
orrhagic cystitis. This treatment has resulted in acute
aluminum intoxication among patients with some
degree of renal insuffi ciency (Phelps et al ., 1999).

of aluminum body burden suggested a critical level of
aluminum was 110-160 g/L in urine.

A Swedish study compared 38 aluminum weld-
ers with a control group of 39 steel welders (Sjögren
et al ., 1996). The median employment time as aluminum
welder was 15 years. Aluminum welders performed
less well than the reference group on four tests of motor
function: fi nger tapping, two tasks of the Luria-Nebraska
battery, and a pegboard test. For the former three tests,
this effect was dose-related and observed in a subgroup
of 19 highly exposed welders who had a median urine
concentration of 59

µ

6.4.3 Neurobehavioral Effects of Occupational
Aluminum Exposure

Several studies of welders have been performed in
Finland to assess the potential for occupational alu-
minum exposure to produce adverse neurobehavioral
effects. The fi rst, comprising 17 participants, did not
use a control group but compared data for subgroups
of welders with differing exposures. Dose-effect rela-
tionships between aluminum levels in serum and
urine and performance on four tests of memory func-
tion (symbol learning, memory-for-designs, digit
span, and associative learning) were found (Hänninen
et al ., 1994). The mean level of aluminum in urine was
75

g aluminum/L. In fi ve of the 19
welders, the urine aluminum exceeded 100

µ

g/L.
A Norwegian study compared a group of 20 alumi-
num welders with a reference group of construction
workers (Bast-Pettersen et al ., 2000). The welders per-
formed better than the construction workers in several
of the tests used. However, when performance of the
welders was analyzed separately, signifi cant correla-
tions were found between exposure duration in years
and poorer performance on the tremor test. Perform-
ance on a test of reaction time was found to be worse
for workers exposed to higher levels of aluminum in
the air. The median urine aluminum for this group was
41

µ

g/L. The second article (Akila et al ., 1999) reported
data from 51 aluminum welders and 28 controls, who
were divided into three groups according to the levels
of aluminum in urine. The low exposure group had
a mean of 12

µ

g/L.
In two German longitudinal studies of aluminum
welders' psychometric measurements were performed
2 years apart. One study had 98 aluminum welders
from the car industry and 50 nonexposed car produc-
tion workers (Buchta et al ., 2003). The median urinary
aluminum was 58

µ g/L, and the range was 19-129 µ

µ g/L, the medium exposed group had

60 g/L.

Dose-related impaired performance attributed to alu-
minum was found on the digit symbol, synonyms,
embedded fi gures, memory for designs, and block
design tests. The third article from this research team
reported on the same worker groups, with the addi-
tion of further welders (Riihimäki et al ., 2000). Weld-
ers were assigned to one of three groups according
to a combined measure of aluminum in serum and
in urine to provide an indication of aluminum body
burden. The three groups were composed of 25, 29,
and 30 workers. The median urinary aluminum lev-
els were 11, 49, and 192

µ g/L, and the high exposure group had 269 µ

g/L in 2001,
and the median exposure time was 6 years. No sig-
nifi cant differences in psychomotor performance or
other neurobehavioral tasks, except for reaction time,
were observed. A second study compared 44 alumi-
num welders in the train body and truck trailer indus-
try with 37 nonexposed production workers (Buchta
et al ., 2005). Median urinary aluminum was 130

µ g/L in 1999 and 52 µ

µ g/L

g/L, respectively. Signifi -
cant group differences were found with respect to
symptoms of fatigue, memory and concentration,
and emotional lability. Six of 18 psychological tests of
memory and concentration also showed signifi cant
group differences, with a lower performance in the
highly exposed groups. Furthermore, there were EEG
differences between the exposure groups. A number
of subjects in the exposed groups exhibited mild or
moderate diffuse or epileptiform abnormalities.
To evaluate dose-response relationships, the prevalence
of fi ndings in six critical domains (symptoms, visual
accuracy, attention, verbal, visuospatial memory, and
EEG) was examined. The proportion of deviant fi nd-
ings in these domains was between 15 and 20%. A plot
of the number of deviant fi ndings against the measure

µ in 1999 and 150 g/L in 2001. Mean exposure time was

11 years. Welders showed signifi cantly poorer per-
formance in symbol-digit substitution, block design,
and, to some extent, in switching attention, but not
in reaction time. The fi rst study (Buchta et al ., 2003)
revealed a small, but statistically insignifi cant, increase
in the reaction-time difference between the fi rst and
second examination. In the second study (Buchta et al .,
2005), no trend differences compared with the controls
were seen. The lack of any differences between the two
examinations might be explained by the short period
for follow-up. A third examination, which is planned
for both studies, may clarify this picture, unless further
nonparticipation biases the group comparison.
There are two studies of psychometric performance
by workers exposed to aluminum powder. Neither of

µ