Soil Bioavailability at Superfund Sites: Guidance

Related Soil Bioavailability Pages

This page contains context and links to soil bioavailability guidance documents. On this page:

Metals

Guidance for Evaluating the Bioavailability of Metals in Soils for Use in Human Health Risk Assessment

This guidance document provides: 1) a recommended process for deciding when to collect site-specific information on the oral bioavailability of metals in soils for use in human health risk assessments; 2) a recommended process for documenting the data collection, analysis and implementation of a validated method that would support site-specific estimates of oral bioavailability; and 3) general criteria for EPA to use in evaluating whether a specific bioavailability method has been validated for regulatory risk assessment purposes.

Standard Operating Procedure for an In Vitro Bioaccessibility Assay for Lead and Arsenic in Soil

The purpose of this standard operating procedure (SOP) is to define the proper analytical procedure for the validated in vitro bioaccessibility assay for lead and arsenic in soil, originally described in Estimation of Relative Bioavailability of Lead in Soil and Soil-like Materials Using In Vivo and In Vitro Methods (EPA, 2007). The SOP also describes the typical working range, the limits of the assay and any potential interferences.

The following reports are round robin analyses of the Flat Creek Soil Standard Reference Materials for lead and arsenic via the in vitro bioaccessibility assay.

Guidance for Sample Collection for In Vitro Bioaccessibility Assay for Arsenic and Lead in Soil and Applications of Relative Bioavailability Data in Human Health Risk Assessment

This document provides guidance on study design, sample collection, and data analysis for the In Vitro Bioaccessibility Assay and Relative Bioavailability, as well as on the application of this data in Human Health Risk Assessment.

The Frequently Asked Questions on Bioavailability Sampling and Assessment (Attachment A) provides answers to common questions and issues that arise in sampling, analyzing, and applying bioavailability data.

Example calculations are provided in Attachment B (Calculation of IEUBK Model and Adult Lead Methodology (ALM) Absorption Fraction Parameter from IVBA Results of EPA Method 1340) and provide step by step illustrations of how to calculate the Absorption Fraction Parameter and the Absorption Fraction for Soil and Dust from In Vitro Bioaccessibility data. The Absorption Fraction Parameter represents lead bioavailability in the Integrated Exposure Uptake Biokinetic Model for Lead in Children and the Absorption Fraction for Soil and Dust represents lead bioavailability in the Adult Lead Methodology Model.

Case Studies on applying In Vitro Bioaccessibility and Relative Bioavailability Data to Human Health Risk Assessment at Superfund Remedial and Removal sites. Attachments C – H provide examples of sites that have used site-specific bioavailability data in the Human Health Risk Assessment.

Lead

Fact Sheet: Relative Bioavailability and In Vitro Bioaccessibility of Lead in Soil

This fact sheet introduces human health risk assessors to the use of bioavailability data to assess risks from incidental ingestion of soils contaminated with lead (Pb) and provides a list of additional resources.

Rationale and Efficacy of Amending Soils with Phosphate as Means to Mitigate Soil Lead Hazard

This fact sheet and journal article discuss the rationale and efficacy of amending soil with phosphate as a means to mitigate soil lead hazard.

Estimation of Relative Bioavailability of Lead in Soil and Soil-like Materials Using In Vivo and In Vitro Methods

These documents address an in vivo swine bioavailability bioassay and an in vitro bioaccessibility assay. These are both scientifically sound and feasible methodologies for predicting the relative bioavailability (RBA) of lead in soil and soil-like materials. EPA’s Office of Superfund Remediation and Technology Innovation (OSRTI) recommends that the Regions rely on these particular test methodologies as validated methodologies for quantitative use in most site-specific risk assessments.

The following is the report of an in vivo swine study on the relative bioavailability of lead and arsenic in NIST 2710a Standard Reference Material:

This report is a round robin analysis of NIST Standard Reference Materials 2710A and 2711A for lead via the in vitro bioaccessibility assay:

Mouse Model for Measuring In Vivo Lead Oral Relative Bioavailability

Technical recommendation to use the mouse model assay to assess the RBA of lead in soils in situations where EPA Method 1340 would not be appropriate. While Method 1340 (In Vitro Bioaccessibility) remains the preferred method to assess site-specific RBA of lead in soil, there are a variety of situations where Method 1340 may not be appropriate, such as where amendments are used to reduce the bioavailability of lead. In such cases, the BAC recommends that a mouse model assay be used.

Arsenic

Fact Sheet: Relative Bioavailability and In Vitro Bioaccessibility of Arsenic in Soil

This fact sheet introduces human health risk assessors to the use of bioavailability data to assess risks from incidental ingestion of soils contaminated with lead (Pb) and provides a list of additional resources.

Relative Bioavailability Of Arsenic In Soils At 11 Hazardous Waste Sites Using An In Vivo Juvenile Swine Method

These documents address an in vivo swine bioavailability bioassay, which is a scientifically sound and feasible methodology for measuring the RBA of arsenic in soil and soil-like materials. OSRTI recommends that the Regions rely on this method for quantitative use in most site-specific risk assessments.

Compilation and Review of Data for Relative Bioavailability of Arsenic in Soil and Recommendations for Default Value for Relative Bioavailability

These documents identified and evaluated literature relevant to estimating an RBA value of arsenic in soil. Based on the analysis and external independent peer review, the following conclusions have been made: 1) currently available research suggests that an RBA of arsenic in soils can be expected to be less than 100 percent; 2) the upper percentile of U.S. data results in a default RBA arsenic in soil value of 60 percent; 3) the default RBA for arsenic in soils should only be used if site-specific assessments for arsenic RBA are not feasible.

​The following document discusses an in vivo swine bioavailability bioassay study of the arsenic in the Flat Creek Soil Reference Material.

The following document discusses the validation of Method 1340 for assessing the in vitro bioaccessibility of lead and arsenic in soils and soil-like materials, as well as the validation of NIST SRM 2710a for use with the method:

Mouse Model for Measuring In Vivo Inorganic Arsenic Oral Relative Bioavailability

Technical recommendation to use the mouse model assay to assess the RBA of inorganic arsenic in soils in situations where EPA Method 1340 would not be appropriate. While Method 1340 (In Vitro Bioaccessibility) remains the preferred method to assess site-specific RBA of inorganic arsenic in soil, there are a variety of situations where Method 1340 may not be appropriate, such as where amendments are used to reduce the bioavailability of inorganic arsenic. In such cases, the BAC recommends that a mouse model assay be used.

Dioxin

Superfund

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Last updated on April 25, 2025