Evaluation of potential health effects by lead exposure using the benchmark dose analysislea

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To clarify the critical dose of lead inducing anemia, the effects of lead on hemoglobin (Hb) and hematocrit (Hct) levels, and red blood cell (RBC) count were examined in 388 male lead-exposed workers aged I 8-67 years, by using the benchmark dose (BMD) approach. The blood lead (BPb) level was associated with Hb (r=-0.240), RBC (r=-0.237) and Hct (r=-0.201) among the workers with BPb levels of 1-i 15 (median 22) μg/dl; these line& relations were statistically significant (p<0.001) even after controlling for age and working status. The critical doses of BPb (i.e., lower 95% confidence limits of BMD) were estimated to be 19.2 μg/dl for Hb, 19.7 μg/dl for RBC, and 29.4 μg/dl for Hct. It is suggested that reduction in hematopoietic indicators may be initiated at BPbs below the level currently considered no effect.To estimate the effects of lead on autonomic nervous system functions, electrocardiographic RR interval variability was measured in 212 workers. The C-CV_<LF>, C-CV_<HF>, LF/HF ratio and QTc were also computed from component spectral powers by means of autoregressive spectral and component analyses. However, these indicators showed no significant associations with BPb and erythrocyte protoporphyrin levels. Further studies with a larger sample size would be needed to confirm the effect of lead on autonomic neurotoxicity.