Persistent increases in scotopic B-wave amplitudes after lead exposure in monkeys.

The electroretinogram (ERG) of rhesus monkeys was re-examined more than 2 years after termination of lead exposure when mean blood lead levels had declined to values below 10 micrograms dl-1. Amplitude of the b-wave was increased by lead exposure at scotopic conditions, while there were no changes in photopic signals. The lead-induced effects were similar 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 dopaminergic processes since immunoreactivity also revealed adverse effects on the dopaminergic system in the retinae of these monkeys.