Interconnected soil iron and arsenic speciation effects on arsenic bioaccessibility and bioavailability: a scoping review

ABSTRACT

Extensive research has examined arsenic (As) bioavailability in contaminated soils and is routinely assessed using in vitro bioaccessibility (IVBA) assays. Analysis of differences in bioaccessibility measurements across IVBA assays and phases is expected to provide valuable insights into geochemical mechanisms controlling soil As bioaccessibility and bioavailability. Soil iron (Fe) content and As speciation are expected to significantly influence IVBA gastric and intestinal phases due to fluctuations in precipitation-dissolution chemistry and sorption reactivity as pH and assay chemical complexity changes. The aim of this review was to examine these relationships by 1) conducting a meta-analysis (n = 47 soils) determining the influence of total Fe on As bioaccessibility measurements and 5 IVBA assays and 2) investigating the effect of As speciation on gastric/intestinal phase IVBA and in vitro-in vivo correlations. Our findings indicate that soil Fe content and As speciation heterogeneity are important in elucidating variability of bioaccessibility measurements across IVBA assays and gastrointestinal phases. Greater focus on coupled As speciation and Fe precipitation chemistry may (1) improve our understanding of soil geochemical factors and assay constituents that influence As in vitro-in vivo correlations and (2) resolve variability in the precision of oral relative bioavailability (RBA) estimated using IVBA assays for soils possessing heterogenous As speciation and Fe composition.

KEYWORDS:

• Arsenic
• bioaccessibility
• bioavailability
• iron
• speciation
• meta-analysis
• sorption
• coprecipitation

Acknowledgments

Portions of this work were funded by U.S. Environmental Protection Agency Office of Superfund Remediation and Technology Innovation (OSRTI) under contract 68HERH19D022 (Task Order 68HERH19F0313). We thank Kasey Kovalcik and Wilson Salls for their internal reviews of this manuscript. This document is being subjected to review by the Center of Environmental Measurement and Modeling (CEMM) for publication. Approval does not signify that the contents reflect the views of the Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available from the corresponding author, TDS, upon reasonable request.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

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Funding

The author(s) reported there is no funding associated with the work featured in this article.