No cognitive deficits in men formerly exposed to lead.
OBJECTIVE
The objective of the study was to investigate long-term cognitive effects resulting from low to moderate lead exposure below current threshold values. Executive functions, attention, visuospatial and visuomotor functioning in workers formerly exposed to lead were investigated.


METHODS
48 men formerly exposed to lead and with a mean current blood level (PbB) of 5.4 microg Pb/100 ml were investigated, together with 48 matched controls (PbB, 4.7 microg Pb/100 ml) out of a pool of 61 males. The two groups were matched for age, years spent in education, verbal intelligence and gram alcohol consumption per week. The following neuropsychological tests were used: modified Wisconsin card sorting test, block design test, visual recognition test, simple reaction time, choice reaction and digit-symbol substitution. Lead exposure was assessed using both current and cumulative measurements.


RESULTS
There were no significant differences in cognitive parameters between the two groups. When analyzing dose-response relationships, negative correlations were found between PbB and performance in the block design test, and between PbB and scores in the visual recognition and digit-symbol substitution tests. High cumulative exposure (IBL, >5000; duration of exposure, >5 years) correlated only with wrong reactions in the choice reaction test.


CONCLUSIONS
The results of our study indicate that cognitive deficits resulting from low-level exposure to lead are reversible. The study was limited to low-level long-term exposure (all PbB values were always below 55 microg Pb/100 ml), and extrapolation of these results to persons heavily exposed to lead is not possible.
Winker
Robert
R
Division of Occupational Medicine, Medical University of Vienna, Vienna, Austria. robert.winker@medunivie.ac.at
Barth
Alfred
A
Ponocny-Seliger
Elisabeth
E
Pilger
Alexander
A
Osterode
Wolf
W
Rüdiger
Hugo W
HW
D000328:Adult; D001317:Austria / Q000453:epidemiology; D003072:Cognition Disorders / Q000097:blood* / Q000453:epidemiology*; D006801:Humans; D007221:Industry; D007854:Lead / Q000097:blood*; D007855:Lead Poisoning / Q000097:blood* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000097:blood* / Q000453:epidemiology*; D015995:Prevalence; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors
D007854:Lead