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.

Soil abatement was associated with a significant decline in children's blood lead and indoor environmental levels of lead and arsenic.

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Soil abatement was associated with a significant decline in children's blood lead and indoor environmental levels of lead and arsenic.

Subacute (10-day) and subchronic (90-day) toxicity studies of ethylene glycol (EG) were conducted in male and female Sprague-Dawley rats to provide the U.S. Environmental Protection Agency's (EPA) Office of Drinking Water with toxicity data for final preparation of a Health Advisory for the chemical. Ethylene glycol was administered in drinking water at concentrations of 0.5, 1.0, 2.0, and 4.0% for both sexes in the 10-day study. Based on a projected consumption rate of 100 ml/kg/day, the respective doses on a mg/kg/day basis would be 554, 1108, 2216, and 4432. These dose levels were also used in the 90-day study for females, but dose levels for the males in the 90-day study were 0.25, 0.5, 1.0, and 2.0% (227, 554, 1108, and 2216 mg/kg/day). At time of sacrifice necropsies were performed and tissues were prepared for histological evaluation. Blood samples were taken for hematology and clinical chemistry determinations. Body weights were measured weekly. Water and food consumption were determined three times weekly. No mortality occurred in the 10-day study. In the 90-day study 8/10 females and 2/10 males in the high dose group died prior to sacrifice. Body weights were suppressed in a dose response fashion for males and females. Hemoglobin, hematocrit, erythrocytes, and leukocytes were all significantly decreased in female rats receiving 4% EG for 10 days. The most significant histopathological findings, seen predominantly in males, were kidney lesions which included calcium oxalate crystals in tubules and pelvic epithelium; tubular dilation and degeneration; intratubular proteinaceous material; and inflammation in tubules and pelvic epithelium. At the same dose of ethylene glycol, males had more kidney lesions and much higher incidence and severity of lesions than the females.