Selected Chemical and Physical Properties of Soils and Gut Physiological Processes that Influence Lead Bioavailability

Abstract

and lower) have been observed. This condition is phytotoxic to plants and the deficiency of plant cover increases the likelihood for soil lead ingestion. After ingestion, nutritional status becomes an important factor with both iron and calcium deficiencies increasing lead bioavailability. To complement the other discussions of the Gl tract and bioavailability in this volume, the following physiological responses of the gut that either increase or decrease soil lead bioavailability are described: (1) The role of the 'normal' microbial flora in altering baseline gut function, (2) effect of pH, (3) intestinal transit time, (4) role of mucus, and (5)

Bioaccessibility of Metals in Soils for Different Liquid to Solid Ratios in Synthetic Gastric Fluid

“…These results are consistent with previous observations made at single liquid to solid ratios (12,17,24,25). There was a statistically significant difference in the bioaccessible fraction of Pb, As, and Cr measured for each ratio within a soil, as well as for the individual metals between soils, suggesting that soil matrix, element, and/or compound play a role in bioaccessibility.…”

Peer Reviewed: Reducing Children's Risk from Lead in Soil

“…In a review of drug absorption, Kararli (28) concluded that no single animal can mimic the gastrointestinal tract characteristics of humans, although it is possible to select the right animal model for a specific purpose. Thus, the debate about which animal model (e.g., weanling pigs or weanling rats) is most appropriate as a surrogate for children has become a subset of issues that need to be addressed (14,(29)(30)(31)(32). Animal-dosing studies are complex, expensive, and time-consuming; it is preferable therefore to ultimately identify a battery of chemical or physical tests that will dependably mimic and predict the bioavailability of soil lead to humans (see Supporting Information).…”

Subchronic lead feeding study in male rats and micropigs

“…Lead bioavailability, in general terms, can be defined as that portion of ingested lead that is retained by the body to interact with the various ongoing metabolic processes. A number of chemical, physical, and physiological factors, including Ca 21 , Fe 21 , diet composition, gut pH, etc., are involved in the absorption of ingested lead into the body and deposition in various tissues (Barltrop and Khoo, 1975;Barltrop and Meek, 1975;Flanagan et al, 1982;Heard et al, 1983: Hemphill et al, 1991Mielke and Heneghan, 1991). Since nutritional and physiological processes are easier and cheaper, to study in rats than in larger mammals, many health regulatory guidelines for humans have been established based on studies done in rats.…”