A comprehensive neurobehavioral and neurophysiological study for low level lead-exposed workers

A comprehensive neurobehavioral and neurophysiological study was performed to evaluate the adverse effect of low level lead-exposure, and to compare the sensibility, easiness of the test methods utilized. The tests were: WHO recommended Neurobehavioral Core Test Battery (NCTB), Autonomic Nouvers System Function (ANS) Test Battery, Brain Electricity Active Mapping (BEAM), and Nerve Conduction Velocity. 44 lead-exposed workers were selected, with 34 age, education degree, family economic level, smoking and drinking matched referents.

The mean blood lead concentration of lead-exposed workers was 1.3870 mumol/L, whereas that of referents was 0.6080 mumol/L, the difference was very significant. The negative Profile of Mood State (POMS) score of lead-expose workers was higher than that of referents, whereas the positive POMS score of the referents was higher than that of lead-exposed group, with a covariance analysis. The lead-exposure affected some NCTB test items, such as simple reaction time (SRT), digital symbol (DSY), correct dots (PAC) and total dots (PA). The heart-rate response to Valsalva manoeuvre (HR-V), heart-rate response to deep breathing (HR-DB), and blood-pressure response to immediate standing (BP-IS) were lowered in lead-exposed workers significantly. Some abnormal brain electric waves (dominant beta frequency, semetry-diffuse abnormal and non semetry-diffuse abnormal wave distribution, dominant low wave amplitude) appeared in lead-exposed workers. Left ulnar nerve maximal conduction velocity was significantly lowered in lead-exposed group.

The NCTB (including POMS), and ANS function test should be the regular screening battery for low level lead-exposed workers. The threshold blood lead concentration for health surveillance should be 30 micrograms/dL, or 1.4 mumol/L.