Associations of tibia lead, DMSA-chelatable lead, and blood lead with measures of peripheral nervous system function in former organolead manufacturing workers

Background. The goals of the present study were to compare and contrast associations of blood lead. DMSA-chelatable lead, current tibia lead, and back-extrapolated "peak" tibia lead with four peripheral nervous system (PNS) sensory and motor function measures in older trades with past exposure to organic and inorganic lead. Methods. Data were collected from former organolead manufacturing workers with an average of 16 years since last occupational lead exposure. Current tibia lead levels were measured by ¹⁰⁹Cd x-ray fluorescence. Sensory pressure thresholds (index and pinky fingers) and pinch and grip strength were measured with the Pressure-Specified Sensory Device (PSSD). Results. In adjusted analyses, none of the four lead biomarkers was associated with sensory pressure threshold of the index finger or pinch or grip strength. In contrast, all four biomarkers were associated (P ≤ 0.10) with pressure threshold of the pinky finger. The final linear regression models accounted for a small proportion of the variance in the sensory (1-3%) and motor measures (10-21%). Conclusions. This study found no strong association between lead biomarkers and selected PNS sensory or motor function measures among former organolead manufacturing workers with no recent occupational exposure to lead. Previously reported CNS findings in this cohort suggest that the PNS may be less sensitive to the chronic toxic effects of lead in this dose range among adults. It is also possible that the PNS has a greater capacity for repair than does the CNS, or that the PNS measures were less sensitive for detection of lead-related health outcomes than were the CNS measures.