A methodological consideration for blood lead concentrations obtained from the earlobe in Japanese adults occupationally unexposed to lead

BACKGROUND Neuropsychological effects of considerably low levels of lead exposure are observed in children, and a reliable and possibly painless technique that can detect such levels is required for the assessment of such exposure. We examined whether the blood lead (BPb) concentrations obtained from the earlobe were as valid and useful as those from the median cubital vein. METHODS Paired blood samples were collected from the earlobe and cubital vein of 112 Japanese participants occupationally unexposed to lead, and the BPb levels were determined using ICP-MS. RESULTS The limit of detection of BPb for the ICP-MS method was 0.015 μg/dL, and there was no participant with a BPb level below this limit. The median values of BPb concentrations were 0.91 (range, 0.41-2.48) μg/dL for earlobe blood using a 175-μL capillary tube and 0.85 (0.35-2.39) μg/dL for venous blood using a 5-mL vacuum tube. There was a significant correlation between the earlobe BPb levels and cubital vein BPb levels (Spearman rank correlation r S = 0.941), though the earlobe BPb levels were significantly higher than the cubital vein BPb levels. Most of the participants regarded earlobe puncture as a painless method. CONCLUSIONS These data suggest that earlobe BPb levels can be used to assess lead exposure in children. Blood collection using a capillary tube should be done carefully and promptly because slow withdrawal may lead to measurement bias.