Estimation of Relative Bioavailability of Lead in Soil and Soil-Like MaterialsUsing Young Swine

Abstract

In this article we summarize the results of a series of studies that measured the relative bioavailability (RBA) of lead in a variety of soil and soil-like test materials. Reference material (Pb acetate) or Pb-contaminated soils were administered orally to juvenile swine twice a day for 15 days. Blood samples were collected from each animal at multiple times during the course of the study, and samples of liver, kidney, and bone were collected at sacrifice. All samples were analyzed for Pb. We estimated the RBA of a test material by fitting mathematical models to the dose–response curves for each measurement end point and finding the ratio of doses that gave equal responses. The final RBA for a test material is the simple average of the four end point–specific RBA values. Results from 19 different test materials reveal a wide range of RBA values across different exposure materials, ranging from 6 to 105%. This variability in RBA between different samples highlights the importance of reliable RBA data to help improve risk assessments for Pb in soil. Although the RBA value for a sample depends on the relative amounts of the different chemical and physical forms of Pb present, data are not yet adequate to allow reliable quantitative predictions of RBA from chemical speciation data alone.

Lead speciation in indoor dust: a case study to assess old paint contribution in a Canadian urban house

“…Consistent with in situ bioavailability values obtained by Casteel et al (2006), the relative bioaccessibility for the identified inorganic Pb phases in house dust are as follows: Pb on goethite (very high-92% relative to Pb acetate = 100%) [ PbCO 3 (high-73%) [ PbO (medium to high-67%) [ PbSO 4 (low-14%) [ PbCrO 4 (very low-9%). These results along with those from XANES speciation (Table 2) indicate that up to 89% of the total Pb in the composite-36 sample would be highly bioaccessible.…”

Potential health impacts of heavy-metal exposure at the Tar Creek Superfund site, Ottawa County, Oklahoma

“…This question was answered in a recent study of the relative bioavailability (RBA) of lead in blood, liver, kidney, and femur from soil exposures in Joplin, Missouri (located in Jasper County) (Casteel et al 2006). RBA was tested by feeding a precise dose of lead in soil to juvenile swine.…”

Lead bioaccessibility in 12 contaminated soils from China: Correlation to lead relative bioavailability and lead in different fractions

“…At present, several in vivo animal modelsincluding mouse and swine have beenused to assess Pbrelative bioavailability (RBA, relative to water soluble lead acetate) [11][12][13][14].However, in vivo assays are costly and time consuming, therefore not suitable to measure site-specific Pb-RBA on a large scale. As a result, various in vitro assays to determine Pb bioaccessibility have been developed, whichmeasures the soluble Pb fraction from soil in simulatedhuman gastrointestinalfluids [10][11][15][16].…”