Comparative Absorption of Lead from Contaminated Soil and Lead Salts by Weanling Fischer 344 Rats

Freeman, G. B.; Dill, Jeffrey A.; Johnson, Jerry D.; Kurtz, P. J.; Parham, Fred; Matthews, H. B.

doi:10.1093/toxsci/33.1.109

Cited by 21 publications

(22 citation statements)

References 17 publications

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“…The distinct blood Pb plateau in the rat may reflect the higher doses administered in the rat bioassay (1000-6000 µg/kg bw/d) compared to the swine bioassay (<500 µg/kg bw/d). The existence of a blood Pb doseresponse plateau in rats, at this dose range, is consistent with saturation of a capacity-limited absorption mechanism for Pb which saturates at high Pb doses (>1000 µg/kg bw) and results in a decreasing absorption fraction with increasing dose Fung, 1981, 1985;Freeman et al, 1992Freeman et al, , 1996. However, lower blood Pb plateaus for soil Pb compared to Pb acetate suggest that some component of soil depresses the maximal capacity for Pb absorption.…”

supporting

confidence: 70%

Amending Soils With Phosphate As Means To Mitigate Soil Lead Hazard: A Critical Review Of The State Of The Science

Scheckel

Diamond

Burgess

et al. 2013

Journal of Toxicology and Environmental Health, Part B

128

179

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Ingested soil and surface dust may be important contributors to elevated blood lead (Pb) levels in children exposed to Pb contaminated environments. Mitigation strategies have typically focused on excavation and removal of the contaminated soil. However, this is not always feasible for addressing widely disseminated contamination in populated areas often encountered in urban environments. The rationale for amending soils with phosphate is that phosphate will promote formation of highly insoluble Pb species (e.g., pyromorphite minerals) in soil, which will remain insoluble after ingestion and, therefore, inaccessible to absorption mechanisms in the gastrointestinal tract (GIT). Amending soil with phosphate might potentially be used in combination with other methods that reduce contact with or migration of contaminated soils, such as covering the soil with a green cap such as sod, clean soil with mulch, raised garden beds, or gravel. These remediation strategies may be less expensive and far less disruptive than excavation and removal of soil. This review evaluates evidence for efficacy of phosphate amendments for decreasing soil Pb bioavailability. Evidence is reviewed for (1) physical and chemical interactions of Pb and phosphate that would be expected to influence bioavailability, (2) effects of phosphate amendments on soil Pb bioaccessibility (i.e., predicted solubility of Pb in the GIT), and (3) results of bioavailability bioassays of amended soils conducted in humans and animal models. Practical implementation issues, such as criteria and methods for evaluating efficacy, and potential effects of phosphate on mobility and bioavailability of co-contaminants in soil are also discussed.

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supporting

confidence: 70%

Amending Soils With Phosphate As Means To Mitigate Soil Lead Hazard: A Critical Review Of The State Of The Science

Scheckel

Diamond

Burgess

et al. 2013

Journal of Toxicology and Environmental Health, Part B

128

179

View full text Add to dashboard Cite

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“…When test animals ingest contaminants in a soil matrix, in general less absorption occurs and fewer toxic effects are observed than when they ingest the same contaminants in a food or liquid matrix (6)(7)(8). The difference can be ascribed to a lower oral bioavailability, resulting from a lower bioaccessibility for contaminants in soil than for contaminants in food or liquid.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Five In Vitro Digestion Models To Study the Bioaccessibility of Soil Contaminants

Oomen

Hack

Minekus

et al. 2002

Environ. Sci. Technol.

720

437

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Soil ingestion can be a major exposure route for humans to many immobile soil contaminants. Exposure to soil contaminants can be overestimated if oral bioavailability is not taken into account. Several in vitro digestion models simulating the human gastrointestinal tract have been developed to assess mobilization of contaminants from soil during digestion, i.e., bioaccessibility. Bioaccessibility is a crucial step in controlling the oral bioavailability for soil contaminants. To what extent in vitro determination of bioaccessibility is method dependent has, until now, not been studied. This paper describes a multi-laboratory comparison and evaluation of five in vitro digestion models. Their experimental design and the results of a round robin evaluation of three soils, each contaminated with arsenic, cadmium, and lead, are presented and discussed. A wide range of bioaccessibility values were found for the three soils: for As 6-95%, 1-19%, and 10-59%; for Cd 7-92%, 5-92%, and 6-99%; and for Pb 4-91%, 1-56%, and 3-90%. Bioaccessibility in many cases is less than 50%, indicating that a reduction of bioavailability can have implications for health risk assessment. Although the experimental designs of the different digestion systems are distinct, the main differences in test results of bioaccessibility can be explained on the basis of the applied gastric pH. High values are typically observed for a simple gastric method, which measures bioaccessibility in the gastric compartment at low pHs of 1.5. Other methods that also apply a low gastric pH, and include intestinal conditions, produce lower bioaccessibility values. The lowest bioaccessibility values are observed for a gastrointestinal method which employs a high gastric pH of 4.0.

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“…Not only are young children more likely to absorb lead (they absorb approximately 50% of all lead inhaled or ingested, compared to approximately 10% for adults) but the effects at lower levels are more likely to be greater and ongoing (Anthony, 2003). Extensive reports and reviews are available on the systemic, immunological, neurological, developmental, reproductive, genotoxic and carcinogenic effects of acute to chronic lead exposure by the inhalation, oral and dermal routes of administration (Freeman et al, 1996). Therefore, considerable effort has been made to treat Pb-containing wastes.…”

Section: Introductionmentioning

confidence: 99%

Kinetic research on the sorption of aqueous lead by synthetic carbonate hydroxyapatite

Yang

Wang

et al. 2008

Journal of Environmental Management

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Comparative Absorption of Lead from Contaminated Soil and Lead Salts by Weanling Fischer 344 Rats

Cited by 21 publications

References 17 publications

Amending Soils With Phosphate As Means To Mitigate Soil Lead Hazard: A Critical Review Of The State Of The Science

Amending Soils With Phosphate As Means To Mitigate Soil Lead Hazard: A Critical Review Of The State Of The Science

Comparison of Five In Vitro Digestion Models To Study the Bioaccessibility of Soil Contaminants

Kinetic research on the sorption of aqueous lead by synthetic carbonate hydroxyapatite

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