title: 5-year follow-up study of children with low-to-moderate lead absorption: electrophysiological evaluation.
abstract: Forty-nine children aged 6 to 12 years were evaluated for residual effects of lead exposure using psychometric, electrophysiological, and medical tests 5 years after initial assessment. The original range of blood lead (PbB) levels was 6-59 (mean = 28) micrograms/dl; the current range was 6-30 (mean = 14) micrograms/dl. A linear relationship between PbB and slow brain wave voltage during sensory conditioning was observed at initial evaluation and at 2-year follow-up. No significant relationship between PbB and slow wave voltage during passive conditioning was found at the 5-year follow-up, although a linear increase in slow wave negativity relative to the current PbB level during active conditioning was suggested by exploratory analyses. Another exploratory analysis revealed a significant linear relationship between the original PbB levels and the latency of waves III and V of the brainstem auditory evoked potential. The latency of both waves increased as a function of original PbB. Increased latency of these waves is suggestive of subclinical pathology of the auditory pathway rostral to the cochlear nucleus, although end-organ impairment cannot be ruled out. No threshold for the effect of Pb on auditory function was apparent.
mesh_terms: D001921:Brain / Q000187:drug effects*; D001933:Brain Stem / Q000187:drug effects; D002648:Child; D003213:Conditioning, Psychological / Q000187:drug effects; D004569:Electroencephalography; D004585:Electrooculography; D005072:Evoked Potentials, Auditory / Q000187:drug effects; D005074:Evoked Potentials, Visual / Q000187:drug effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007854:Lead / Q000097:blood; D007855:Lead Poisoning / Q000503:physiopathology*; D008297:Male
chemical_list: D007854:Lead