Biological availability of lead in a paint aerosol. 2. Absorption, distribution and excretion of intratracheally instilled lead paint particles in the rat.

Four groups of rats received by intratracheal instillation (1) a lead chromate paint particulate suspension, (2) lead tetraoxide suspension, (3) lead acetate solution, or (4) saline. Lead-dosed animals received an equivalent dose of 1 mg lead/kg body weight. Distribution of lead was monitored through assays of urine, feces, and tissues (lung, bone, muscle kidney, liver) obtained at post-mortem 5 weeks after exposure. Delta-aminolevulinic acid dehydratase (ALA-D) activity was measured to determine the effect of lead on heme biosynthesis. The vast majority of the dosed lead in the paint matrix remained in the lung. In contrast, in the lead acetate-dosed animals, little remained in the lung, but significant elevations were found in bone and kidney. Blood ADA-D was significantly depressed in the lead acetate-treated animals, but was not significantly different from control animals in the animals dosed with lead paint or lead tetraoxide. These findings suggest that lead chromate in an alkyd resin paint matrix is poorly absorbed from the lung compared with lead acetate and lead tetraoxide.