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.