Neurological and electrophysiological examinations on three groups of workers with different levels of exposure to mercury vapors

The authors performed neurological, visual evoked potentials (VEP) and elec troneurography (ENG) examinations on three groups of workers with occupatio nal exposure to mercury vapors (Hg-o), and on a control group. The exposure of dental professionals (n = 36) was mild, that of chloralkali plant worke rs (n = 36) was intermediate, and that of workers from mercury works (n = 7 7) was very high, Symptoms and signs of micromercurialism were observed onl y in the group with the highest exposure to Hg-o, In comparison with the co ntrol group, a shortening of VEP latency and a decrease in amplitude were f ound in the exposed groups, The VEP changes correlated with Hg-o excreted i n urine after administration of a chelating agent - sodium 2,3-dimercapto-1 -propan sulfonate (DMPS). The frequency of abnormal VEP results increased w ith increasing levels of exposure, ENG changes were observed only in the gr oup with the highest exposure to Hg-o. An isolated decrease of sural nerve conduction velocity was observed in 18% of total workers, In 70% of the cas es, this was associated with an abnormality in VEP, The combination of a de crease in sural nerve conduction velocity and an abnormality of VEP seems t o be a characteristic pattern of electrophysiological changes in persons ex posed to mercury vapors, Eur J Neurol 6:571-577 (C) 1999 Lippincott William s & Wilkins.