Cumulative Blood Lead Levels and Nerve Conduction Parameters

Most studies on the effects of lead on the peripheral nerves used "current' 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 on the peripheral nerves occurs over a period of time. Seventy-two workers in a lead battery manufacturing factory and 82 referents were studied with the aim of (1) correlating the nerve conduction parameters of the median and ulnar nerves of the dominant forearms with the blood cumulative lead-years (BPbCum) results; (2) determining a "noeffect' cumulative dose of lead on the peripheral nerves. The mean BPb for the exposed and referent were 36.9 micrograms/100ml and 10.5 micrograms/100ml, respectively. The mean BPbCum was 136.8 (range = 6.7-1087.0)micrograms-year/100ml. Significant differences were found in the adjusted (for age, ethnical groups, smoking and drinking habits by ANCOVA) means median sensory conduction velocity, motor conduction veloclty, distal latency and amplitude between the exposed and referent groups. But for the ulnar nerve only, distal latency was significantly different. With the BPbCum groups, dose response relations are noted in both the nerve conduction parameters of the median and ulnar nerves. There were no significant differences for the ulnar and median nerves conduction parameters between BPbCum < 40 micrograms-year/100ml group and referent. Based on the study's findings, it would suggest that a maintained blood lead level of less than 40micrograms/100ml for one year may not have significant effects on the median and ulnar nerves.