Absence of peripheral neuropathy in long-term lead-exposed subjects

Abstract

The safety of a blood lead concentration of 70 microgram/100 ml as a hygienic border value with regard to development of lead neuropathy was tested in 95 employees, who had been exposed occupationally to lead for more than 9 years. The blood lead concentration was slightly above the border value in nine subjects, while the erythrocyte-Zn-protoporphyrin concentration was significantly elevated in 81 subjects, indicating an abnormal accumulation of metabolically active lead. None of the group showed clinical evidence of peripheral neuropathy, and the vibratory perception thresholds as well as motor conduction data from the median, radial, and common peroneal nerves were normal, as compared with an age-matched control group of 21 non-exposed normal subjects. The amplitude ratio between proximally and distally evoked muscle action potentials was normal in all lead-exposed subjects. These findings suggest that lead-exposed subjects are well protected against peripheral lead neuropathy, when blood lead levels are kept below the hygienic border value.

Distúrbios neurológicos em trabalhadores com baixos níveis de chumbo no sangue. I: Neuropatia periférica

“…Não obstante, alguns autores não conseguiram demonstrar alterações neurológicas periféricas nestes níveis de exposição 24,27,28,38,40 ; e outros não encontraram distúrbios neurocomportamentais em trabalhadores expostos também a esses níveis 25,28 .…”

Blood pressure and other cardiovascular risk factors of long-term exposure to lead.

“…The facilities used in these investigations gave us an opportunity to study cardiovascular risk factors in' workers exposed to lead on the long-term. In two previous papers we have described these workers' subjective symptoms and studied whether they had peripheral nerve disease (6,7).…”

Subclinical neurophysiological effects of lead: A review on peripheral, central, and autonomic nervous system effects in lead workers

“…Araki and Honma [1976] also found signi®cant correlations between BPbs and NCVs as well as reductions in NCVs in workers with asymptomatically increased lead absorption as described above. These observations have in general been con®rmed by subsequent investigations [Landrigan et al, 1976;Feldman et al, 1977;Repko et al, 1978;Buchthal and Behse, 1979;Seppaelainen et al, 1979Seppaelainen et al, , 1983Seppaelainen and Hernberg, 1980;Araki et al, 1980Araki et al, , 1986aAraki et al, , 1993aAshby, 1980;Bordo et al, 1982;Rosen et al, 1983;Singer et al, 1983;Triebig et al, 1984;Chen et al, 1985;Jeyaratnam et al, 1985;Murata et al, 1987a;Murata and Araki, 1991;He et al, 1988;Hirata and Kosaka, 1993;Fujimura et al, 1998], although they have not been made in all published reports [Baloh et al, 1979;Paulev et al, 1979;Spivey et al, 1980;Nielsen et al, 1982;Pasternak et al, 1989;Yeh et al, 1995]. Among the later six studies which have failed to show signi®cant NCV effects of lead, males and females are mixed in the study subjects of the three studies [Nielsen et al, 1982;Pasternak et al, 1989;Yeh et al, 1995].…”