Bioaccessibility of Trace Metals in Household Dust

Abstract

Household dust is a heterogeneous mixture of micrometer-sized particulates derived from an array of internal and external sources. Many of these sources, including road dust, soil, and decorative materials, are enriched in trace metals, and this is reflected in the composition of indoor dust. The exposure and risk posed by a trace metal in the indoor environment is dependent on the loading of dust, and the absolute concentration and bioaccessibility of the metal of interest. Bioaccessibility is defined as the fraction of total metal that is accessible (or soluble) in the gastrointestinal tract, and is generally determined in vitro by incubating samples in solutions that mimic, successively, chemical conditions encountered in the human stomach and intestine. With regard to household dust, average bioaccessibilities of trace metals in the stomach range from less than 20% (e.g., Cr, Cu, Sn, and U) to greater than 50% (e.g., Cd, Mn, and Zn). For most metals, accessibility is reduced from the stomach to the intestine. However, for metals that form oxyanionic aqueous species (e.g., Cr, U), accessibility is enhanced in the latter.