The effect of lead on brainstem auditory evoked potentials in children

To determine whether lead affects brainstem auditory evoked potentials (BAEPs) in low-to-moderate lead exposed children.

BAEPs were recorded from 114 asymptomatic children aged 1 - 6 years. Average values were calculated for peak latency (PL) and amplitude (Amp). Whole blood lead (PbB) levels were assessed by graphite furnace atomic absorption spectroscopy. Based on their PbB levels, subjects were divided into low lead (PbB < 100 micro g/L) and high lead subgroups (PbB > or = 100 micro g/L).

The PbB levels of the 114 subjects ranged from 32.0 to 380.0 micro g/L in a positively skewed distribution. The median of PbB levels was 90.0 micro g/L while the arithmetic average was 88.0 micro g/L. Of the subjects, 43.0% (49/114) had levels equal to or greater than 100 micro g/L. Bilateral PLs I, V, and III of the left ear in the high lead subgroup were significantly longer than those in the low lead subgroup (P < 0.05). A positive correlation was found between PbB levels and bilateral PLs I, V and III of the left ear (P < 0.05), after controlling for age and gender as confounding factors. A significant and positive correlation between PbB levels and PL I of the left ear, even when PbB levels were lower than 100 micro g/L, in the low subgroup (r = 0.295, P = 0.019) was also found.

Lead poisoning in children younger than 6 years old is a very serious problem to which close attention should be paid. The indications that lead prolongs partial PLs may imply that lead, even at PbB levels lower than 100 micro g/L, impairs both the peripheral and the central portions of the auditory system. BAEPs may be a sensitive detector of subclinical lead exposure effects on the nervous system in children.