PERCUTANEOUS-ABSORPTION OF INORGANIC LEAD COMPOUNDS

In vivo experiments with the stable lead isotope, Pb-204, have confirm ed that inorganic lead compounds can be absorbed through the skin. Thr ee different analytical techniques - thermal ionization mass spectrome try, inductively coupled Plasma mass spectrometry and anodic stripping voltammetry - showed that lead, as lead nitrate or lead acetate, was rapidly absorbed through the ski and det table in sweat, blood and uri ne within 6 h of skin application Of the 4.4 mg of lead applied to the skin in one experiment, 1.3 mg was absorbed within 24 h. Initial rapi d uptake was probably via sweat glands and hair follicles, followed by slower absorption via the transepidermal route. While increases in Pb -204 concentration and abundance were observed, no increase in total l ead in blood or urine w found. It is possible that the physicochemical form of skin-absorbed lead partitions strongly into extracellular flu id, but has a low affinity for erythrocytes. There was no significant difference in uptake of lead into erythrocytes (in vitro) from normal saline, synthetic sweat or sauna sweat. Ultrafiltration of sweat showe d that up to 70% of lead in sweat was associated with > 30 000 MW part icles. It is possible that percutaneous absorption of lead could contr ibute significantly to lead body burden, particularly from occupationa l exposure to lead in dust. Moreover, because lead absorbed through th e skin was only just detectable in blood, and blood lead is the main c riterion by which industry determines exposure, skin-absorbed lead may remain undetected.