RELATION BETWEEN EXPOSURE RELATED INDEXES AND NEUROLOGICAL AND NEUROPHYSIOLOGICAL EFFECTS IN WORKERS PREVIOUSLY EXPOSED TO MERCURY-VAPOR

A cross sectional study of aspects of their neurology was carried out on 77 chloralkali workers previously exposed to mercury (Hg) vapour an d compared with 53 age matched referents. The chloralkali workers had been exposed for an average of 7-9 years at a concentration of 59 mug Hg/m3 in the working atmosphere. The individual mean urinary concentra tion of Hg for each year of exposure was 531 nmol Hg/1. On average the exposure had ceased 12.3 years before the examinations. Both the medi an sensory nerve conduction velocity and the amplitude of the sural ne rve were associated with measures of cumulative exposure to Hg. An ass ociation was also found between years since first exposure to Hg and a spects of the visual evoked response. Previously exposed subjects with postural tremor or impaired coordination also had alterations in visu al evoked response. These results may indicate an effect of previous e xposure to mercury vapour on the nervous system, possibly in the visua l pathway, cerebellum, and the peripheral sensory nerves.