CUMULATIVE BLOOD LEAD LEVELS AND NERVE-CONDUCTION PARAMETERS

Most studies on the effects of lead on the peripheral nerves used 'cur rent' blood lead levels of the workers and infer the nerve conduction' s findings to it. This practice is not ideal as the toxicity of lead o n the peripheral nerves occurs over a period of time. seventy-two work ers in a lead battery manufacturing factory and 82 referents were stud ied with the aim of (1) correlating the nerve conduction parameters of the median and ulnar nerves of the dominant forearms with the blood c umulative lead-years (BPbCum) results; (2) determining a 'noeffect' cu mulative dose of lead on the peripheral nerves. The mean BPb for the e xposed and referent were 36.9 mu g/100ml and 10.5 mu g/100ml, respecti vely. The mean BPbCum was 136.8 (range=6.7-1087.0)mu g-year/100ml. Sig nificant differences were found in the adjusted (for age, ethnical gro ups, smoking and drinking habits by ANCOVA) means median sensory condu ction velocity, motor conduction velocity, distal latency and amplitud e between the exposed and referent groups. But for the ulnar nerve onl y, distal latency was significantly different. With the BPbCum groups, dose response relations are noted in both the nerve conduction parame ters of the median and ulnar nerves. There were no significant differe nces for the ulnar and median nerves conduction parameters between BPb Cum <40 mu g-year/100ml group and referent. Based on the study's findi ngs, it would suggest that a maintained blood lead level of less than 40 mu g/100ml for one year may not have significant effects on the med ian and ulnar nerves.