Low-cost screening method for estimating inorganic arsenic in soil

Area of Science:

• Environmental Science
• Analytical Chemistry
• Toxicology

Background:

• Pollution poses risks, yet accessible testing for contaminants like inorganic arsenic is limited.
• Inorganic arsenic is linked to various acute and chronic diseases.
• Limited resources hinder community-based environmental monitoring.

Purpose of the Study:

• To develop and evaluate a low-cost, accessible screening method for inorganic arsenic in soil.
• To adapt a commercial water test kit for soil arsenic analysis.
• To assess the method's ability to estimate bioaccessible and total inorganic arsenic.

Main Methods:

• Adapted a commercial water test kit for soil screening.
• Evaluated two extraction solutions for bioaccessible and total inorganic arsenic.
• Characterized 151 soil samples and standards using the screening method and laboratory analysis.

Main Results:

• The bioaccessible screening method estimates in vitro bioaccessible assay (IVBA) arsenic and predicted minimum total arsenic.
• Screening levels of 82.5 µg L⁻¹ and 132.0 µg L⁻¹ predict exceeding AZDEQ and NYDEC regulatory soil levels, respectively.
• False positives were minimal; false negatives increased near regulatory thresholds, with rates of 0-81.4% depending on the threshold and region.

Conclusions:

• The proposed bioaccessible screening method offers a practical tool for assessing soil arsenic contamination.
• The method can provide physiological insight and estimate total arsenic relative to regulatory standards.
• Further investigation is needed for the total arsenic screening method, but the bioaccessible method is suitable for screening total arsenic down to 8.5 mg kg⁻¹.