Neuropsychological effects were examined in 47 mercury vapor exposed male c
hloralkali workers with current low concentrations of urinary mercury (mean
U-Hg 5.9 nmol/mmol creatinine (Cr)). Their ever-age duration of exposure,v
as 13.3 years, and the calculated mean concentration of U-Hg was 9.0 nmol H
g/nmol Cr per year (exposure intensity) during their time of exposure. They
were compared, with 47 age-matched male referents in a cross-sectional stu
dy. The two groups were nor statistically significantly different with resp
ect to neuropsychological test performance or number of self-reported subje
ctive symptoms. The test results of the Static Steadiness Test, which asses
ses tremor were not associated with exposure to mercury vapor: However curr
ent smokers had more hand tremor than non-smokers. Statistically significan
t associations were found between indices of current exposure (the concentr
ation of inorganic mercury in whole blood) and the results of the WAIS Digi
t Symbol Test and the Benton Visual Retention Test (number of correct respo
nses). This could indicate a small effect of current exposure on visuomotor
/psychomotor speed and attention, and immediate visual memory Whether the a
ssociation found between the historical exposure intensity and the Digit Sy
mbol Test results may represent long-term conseqences of exposure cannot be
determined in this study (C) 2001 Elsevier Science Inc. All rights reserve
d.