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Formation of plumbojarosite (PLJ) reduces bioavailability of soil-borne lead (Pb)
Citation:
Karna, R., Matthew Noerpel, C. Nelson, B. Elek, K. Herbin-Davis, G. Diamond, K. Bradham, K. Scheckel, AND D. Thomas. Formation of plumbojarosite (PLJ) reduces bioavailability of soil-borne lead (Pb). 59th Annual Meeting of the Society of Toxicology, Anaheim, California, March 08 - 19, 2020. https://doi.org/10.23645/epacomptox.12514952
Impact/Purpose:
This abstract describes evaluation of a novel method for the conversion of soil-borne lead into poorly soluble plumbojarosite. The effectiveness of this approach is investigated using a mouse model to measure the relative bioavailability of lead in untreated and treated soils.
Description:
Exposure to Pb during early life has long-lasting adverse effects on health. Ingestion of Pb-contaminated soil is a major route for exposure of children to this toxic metal. Soil remediation procedures that alter physiochemical properties of soil-borne Pb can limit exposure by reducing gastrointestinal Pb uptake. A novel approach for remediation of soil Pb uses addition of iron (Fe) sulfate and application of heat to promote formation of PLJ, a poorly soluble Pb-Fe sulfate compound. Here, two Pb-contaminated soils and samples of a low-lead soil spiked with various Pb compounds (i.e., carbonate, chloride, phosphate, or sulfate) were treated to convert native Pb species to PLJ. We used a mouse assay to examine tissue Pb distribution after ingestion of diets amended with untreated or treated soils. Bone and blood Pb levels were determined to evaluate uptake across the gastrointestinal barrier. For both Pb-contaminated soils and all Pb compounds, bone and blood Pb levels were significantly lower (P<0.001, student t-test) in mice that consumed diets amended with treated soils than in mice that consumed diets amended with untreated soils. After treatment, estimated relative bioavailability (RBA) of Pb in both soils and for all Pb compounds were reduced by more than 90% compared to RBA estimates for untreated soils or compounds. X-ray absorption spectroscopy was used to determine Pb species in soil-amended diets and in feces excreted by mice consuming these diets. Treatment of Pb-contaminated soils or Pb compounds consistently converted more than 90% of all Pb species in these materials to PLJ. Speciation of Pb in feces from mice fed diets containing soils or Pb compounds treated to promote PLJ formation found no evidence that ingested PLJ underwent chemical transformation during transit of the gastrointestinal tract. This evidence suggests that formation of PLJ could be an effective strategy to reduce the RBA of Pb in soil and minimize this medium’s role as a source of exposure to Pb in young children. (This abstract does not represent U.S. Environmental Protection Agency policy.)
URLs/Downloads:
DOI: Formation of plumbojarosite (PLJ) reduces bioavailability of soil-borne lead (Pb)
KARNA ET AL SOT POSTER REVIEW VERSION 02072020.PDF (PDF, NA pp, 509.301 KB, about PDF)