MEASUREMENT BY ICP-MS OF LEAD IN PLASMA AND WHOLE-BLOOD OF LEAD WORKERS AND CONTROLS

Objectives - To test a simple procedure for preparing samples for meas urement of lead in blood plasma (P-Pb) and whole blood (B-Pb) by induc tively coupled plasma mass spectrometry (ICP-MS), to measure P-Pb and B-Pb in lead workers and controls, and to evaluate any differences in the relation between B-Pb and P-Pb between people. Methods - P-Pb and B-Pb were measured by ICP-MS in 43 male lead smelter workers and seven controls without occupational exposure to lead. For analysis, plasma and whole blood were diluted 1 in 4 and 1 in 9, respectively, with a d iluted ammonia solution containing Triton-X 100 and EDTA. The samples were handled under routine laboratory conditions, without clean room f acilities. Results - P-Pb was measured with good precision (CV = 5%) e ven at concentrations present in the controls. Freeze storage of the s amples had no effect on the results. The detection limit was 0.015 mu g/l. The P-Pb was 0.15 (range 0.1-0.3) mu g/l in controls and 1.2 (0.3 -3.6) mu g/l in lead workers, although the corresponding B-Pbs were 40 (24-59) mu g/l and 281 (60-530) mu g/l (1 mu g Pb/l = 4.8 nmol/l). B- Pb was closely associated with P-Pb (r = 0.90). The association was ev idently non-linear; the ratio B-Pb/P-Pb decreased with increasing P-Pb . Conclusions - By means of ICP-MS and a simple dilution procedure, P- Pb may be measured accurately and with good precision down to concentr ations present in controls. Contamination of blood at sampling and ana lysis is no major problem. with increasing P-Pb, the percentage of lea d in plasma increases. In studies of lead toxicity, P-Pb should be con sidered as a complement to current indicators of lead exposure and ris k.