PERSISTENT INCREASES IN SCOTOPIC B-WAVE AMPLITUDES AFTER LEAD-EXPOSURE IN MONKEYS

The electroretinogram (ERG) of rhesus monkeys was re-examined more tha n 2 years after termination of lead exposure when mean blood lead leve ls had declined to values below 10 mu g dl(-1). Amplitude of the b-wav e was increased by lead exposure at scotopic conditions, while there w ere no changes in photopic signals. The lead-induced effects were simi lar to alterations detected during the treatment phase and, thus, are not dependent on current exposure. Taking into account, that dopamine antagonists cause similar changes in the ERG, it is suggested that the observed effects may be mediated by a permanent change of dopaminergi c processes since immunoreactivity also revealed adverse effects on th e dopaminergic system in the retinae of these monkeys.