"ULtra-clean" isotope diultion/mass spectrometic analyses for lead in human blood plasma indicated that most reported values are artificially high.

We measured lead concentrations in venous blood plasma from two subjects, one having a typical exposure and the other a high exposure to lead. Our preliminary data, obtained by isotope dilution/mass spectrometric techniques in an ultra-clean laboratory, show lead concentrations of 0.02 mug/L and 2 mug/L, respectively, in their blood plasma, and 110 mug/L and 800 mug/L, respectively, in samples of whole blood. These results indicate that plasma lead concentrations previously reported have been overestimated by a large factor, and that further improvements in analytical procedures are needed in most laboratories before data on lead concentratios in blood plasma can be properly interpreted. Our preliminary data indicate a positive correlation between lead intake and lead concentrations in blood plasma.