Project Description

Soil Arsenic Bioavailability in Humans

Introduction

A study of Flordia soil arsenic relative bioavailability in human adults was designed and conducted using well characterized Florida soil. The eventual linkage of soil ingestion estimates with the bioavailability information from this study will enable a comprehensive assessment of the oral route exposure of soil-based arsenic.

Study Design

To answer to question of soil arsenic bioiavailability from Florida soil, we conducted an experimental mass-balance study of adults comprised of two study periods with each lasting seven days.

In the first period, 11 adult volunteer subjects (6 females, 5 male between the age of 26 and 53) collected duplicate food samples, and all urine and stool samples over a seven consecutive day period. Samples were analyzed to determine quantities of arsenic.

In the second period, 11 adult volunteer subjects (9 subjects from the first period study, plus two additional subjects) were placed on an arsenic suppression diet three days before the start of the study period. Duplicate food samples, and all urine and stool samples over a seven consecutive day period. On the second day of this study period (between 8 and 9PM) study subjects ingested a capsule containing 0.75 g of Flordia soil, and placed a similar capsule in the duplicate food sample for that day. Samples were analyzed to determine quantities of arsenic.

Assessment of Relative Bioavailability

The first study period data was used to assess the relative amount of arsenic in urine to total urine+stool arsenic as a measure of the food arsenic bioavailability. The second period data was used in combination with the first period data to assess the relative bioavailability of soil arsenic.

Upon initial data review, the amount of arsenic in soil capsules appeared not to be recovered in urine and stool samples. As a result, an additional experimental study of  McDonald's food was conducted to validate the ability to recover soil arsenic from food samples where soil was added. Results from this study contributed to the final assessment of the relative bioavailability of soil-arsenic.