Biomonitoring equivalents for inorganic arsenic

Abstract

This paper presents Biomonitoring Equivalents (BEs) for inorganic arsenic. Biomonitoring Equivalents (BEs) are defined as the concentration or range of concentrations of a chemical or its metabolite in a biological medium (blood, urine, or other medium) that is consistent with an existing health-based exposure guideline, and are derived by integrating available data on pharmacokinetics with existing chemical risk assessments. This study reviews available health-based exposure guidance values for arsenic based on recent evaluations from the United States Environmental Protection Agency (US EPA), US Agency for Toxic Substances and Disease Registry (ATSDR) and Health Canada (HC). BE values corresponding to the Reference Dose (RfD) or risk-specific doses for cancer endpoints from these agencies were derived based on kinetic data (urinary excretion) from controlled dosing studies in humans. The BE values presented here provide estimates of the sum of inorganic arsenic-derived urinary biomarkers (inorganic arsenic, monomethylated arsenic, and dimethylated arsenic). The BE associated with the United States Environmental Protection Agency's Reference Dose and the Agency for Toxic Substances and Disease Registry's Minimal Risk Level is 6.4 microg arsenic/L urine. The BEs associated with the various cancer risk assessments are significantly lower. These BE values may be used as screening tools for evaluation of biomonitoring data for inorganic arsenic in a public health risk context.