[Value of electroencephalographic studies for the evaluation of the neurotoxic effect of metallic mercury].

The results of 373 EEG investigations were analysed. They were obtained in a period of 4 years in 222 workers with occupational exposure to metallic mercury in the synthesis of acetaldehyde and salt electrolysis. Abnormal or borderline abnormal results were found in 13% of them. Results were compared in groups differing in age, duration of occupation, working post and Hg excretion with urine. Significantly greater frequency of increased Hg absorption was found in the group with abnormal records. The authors stressed the following morphological features of EEG in those exposed to Hg: tendency for seizure activity, loss of ability of following of rhythmic flashes, unchanged frequency of background activity despite increasing degree of other abnormalities, absence of low-voltage tracings, persistence of abnormalities in the records after loss of contact with mercury.