Biochemical and electrophysiological study of subjects with a history of past lead exposure

Abstract

The effects of lead on porphyrin metabolism and peripheral nervous system were studied in a group of 38 subjects who had not been exposed for a period of time, ranging from 3 to 27 years. The mean values for blood lead (PbB), chelated lead(PbUEDTA), and free erythrocyte protoporphyrin (FEP) were found to be significantly higher in the subjects with past lead exposure than in controls. In all cases the neurological examination was negative. The mean values for maximum motor conduction velocity (MMCV) and conduction velocity of the slower fibers (CVSF) of the ulnar and peroneal nerves were found to be significantly lower in the subjects with past lead exposure than in the control group of 23 subjects standardized for age. Signs of partial denervation were present in four cases, with two presenting a decrease of the motor conduction velocity (MCV) as well. No correlation was found between electrophysiological findings and biochemical indicators of dose and effect. The length of exposure showed a significant negative correlation only with the MMCV of the ulnar nerve. A significant difference from controls standardized for age was observed only in subjects with exposure of more than 6 months for all the electromyographic (EMG) parameters. It does not appear that the EMG findings could depend upon modest lead deposits still present in the organism; they should rather give evidence to the permanent effect of alterations that occurred during the prolonged exposure to lead.

Sparing of cognitive executive functions and impairment of motor functions after industrial exposure to lead: A field study with control group.

“…It may also have resulted from the significant positive correlation between age and duration of nonexposure ( r = .32) and the significant negative correlation between grip strength and age ( r = −.39). Though workers of the present study had been unexposed to lead for very widely varying time intervals (0 to 84 months, M = 26.66, SD = 27.64), this distribution probably did not overlap with the one reported by Corsi, Bartolucci, Fardin, Negrin, and Manzoni (1984; M = 145 months), who also observed absence of reversibility of motor impairment. Range and standard deviation were unfortunately not mentioned in that report.…”

Lead exposure during demolition of a steel structure coated with lead-based paints. II. Reversible changes in the conduction velocity of the motor nerves in transiently exposed workers.

“…On the basis of the data reported by Corsi et al (7), obtained in a group of seven patients formerly intoxicated with lead for less than three and a half months, such an irreversible change cannot be excluded either . Yet both in the results of Corsi et al (7) and in the present results (table 2 and table 5) the mean values of the workers, long after the termination of exposure , and tho se of the referents are strikingly smilar. These similarities should not simply be dismissed, but should be taken instead as a hint that an irreversible effect of transitory exposure is less likely.…”

Effect of exposure to lead on postural control in workers

“…8 10 14 Effects in workers exposed to lead include decreased central nervous conduction,1 2 cognitive impairment,4-6extrapyramidal signs,3 and peripheral neuropathies 27-10 …”