Bioavailability of Lead in Mining Wastes: An Oral Intubation Study in Young Swine

Experimental determination of the oral bioavailability and bioaccessibility of lead particles

“…USEPA Region VIII scientists conducted in vivo experiments on piglets to estimate the bioavailability of soil Pb particles, and from there the potential burden for infants/children [41,79,80]. The juvenile swine model experimental procedure for assessing oral bioavailability from soils, detailed in Weis et al [41] and further developed by Casteel et al [42], was then applied to a wide variety of soils [60,63,64,70], in some cases with modifications to the original EPA procedure [46,62].…”

“…However, for some animal models, such as the rat, it is often necessary to increase dosages in order to increase BLLs to detectable levels that permit reliable differentiation between the PbAc and the test material [45]. Bioavailability results obtained under such conditions may be underestimated, as the rate of elimination of Pb at these high dosages could be much higher, especially if they largely exceed the saturation concentration for active transport mechanisms in the gut [79]. …”

“…Indeed, Casteel et al found a high RBA (57-58%) for soils of ≤ 250 μm containing a majority of particles ≤ 10 μm [49]. The significant BLLs observed in piglets dosed with “predicted low bioavailable” tailings were partly explained by the small size of the galena crystals (mostly < 10 μm) that were completely dissolved within 50–100 min at a low gastric pH [79]. Rieuwerts et al reported a bioaccessibility of about 61-116% for particles < 64 μm, while particles > 64 μm were 21 to 72% bioaccessible [117].…”

Uses and limits of empirical data in measuring and modeling human lead exposure.

“…Kierski (75) showed that the weanling rabbit, 5 weeks old, absorbs twice as much lead from ingested soil as does the older rabbit. The juvenile swine, interestingly, may be farther along developmentally than the human infant but still appears to absorb lead at relatively high rates from dosed animal feeds or diet augmented with various leaded soils (76)(77)(78)(79)(80)(81)(82).…”

Blood lead concentrations of Swedish preschool children in a community with high lead levels from mine waste in soil and dust.

“…Studying the bioavailability of inorganic lead in rats after oral administration, Freeman et al (44) observed that only a small fraction of lead was absorbed from soil contaminated by mine waste in comparison with lead acetate. In contrast to the ob servations made from rats, LaVelle et al (45 ) reported a relatively high bioavailability of lead derived from mine waste in soil given orally to young pigs.…”