Subclinical vestibulo-cerebellar, anterior cerebellar lobe and spinocerebellar effects in lead workers in relation to concurrent and past exposure.

By computerized static posturography, the subclinical effects of past and concurrent lead absorption on the vestibulo-cerebellum (lower vermis), anterior cerebellar lobe and spinocerebellar afferent pathway were examined in 49 male chemical factory workers exposed to lead stearate (lead workers). Their concurrent blood lead (BPb) concentrations ranged from 7 to 36 (mean 18.0) microgram/100 g. In the past, their maximum BPb ranged from 11 to 113 (mean 47.7) micrograms/100 g; mean BPb was 7-52 (mean 23.5) micrograms/100 g; and cumulative BPb, defined as mean BPb x years of exposure, was 15-1268 (mean 390.6) micrograms.year/100 g. Control subjects were 23 healthy male workers who had never been occupationally exposed to lead. The postural sway of high (2-4 Hz) and low (1 Hz or less) frequencies with eyes open for lead workers was significantly greater than that for controls in the medio-lateral (right-left) and anterior-posterior directions. Similarly, the sway of high and low frequencies with eyes closed was significantly larger in lead workers than in controls in the medio-lateral direction. Results of stepwise multiple regression analysis indicated that the sway with frequencies of 0.5-2 Hz with eyes open was related to concurrent BPb in the anterior-posterior direction. With eyes closed the sway of high frequency was significantly related to mean BPb in the past in the medio-lateral direction. The pattern of the changes suggests that the vestibulo-cerebellum, anterior cerebellar lobe and spinocerebellar pathway are asymptomatically affected by lead. It appears that the change in the vestibulo-cerebellum reflects concurrent lead absorption, while on the other hand, that in the anterior cerebellar lobe reflects past lead absorption.