Oral bioaccessibility of trace metals in household dust: a review |
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Authors: | Andrew Turner |
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Institution: | (1) School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK |
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Abstract: | Because household dust is a heterogeneous assortment of particles derived from a multitude of diverse sources, concentrations
of toxicants, like trace metals, vary widely among sample populations. For risk assessment purposes, the bioaccessibility
of a trace metal, or its degree of solubilization in the human lung or digestive environment, provides a better metric of
its potential health impact than its total concentration. In this paper, the relatively little direct information that exists
on the in vitro oral bioaccessibilities of metals in household dust is reviewed. Data and mechanisms from studies involving
better characterized geosolids, like soil and street dust, or metal-rich components thereof, such as paints, are also extrapolated
to the household setting, although use of these solids as surrogates of household dust is not recommended. The bioaccessibility
of a given metal is highly variable in the household setting; for instance, reported accessibilities of Pb in fluids that
mimic the human stomach range from 25 to 80%, and accessibility is usually, but not always, reduced when conditions are altered
to mimic the intestine. While part of this variation reflects the inherent heterogeneity of samples arising from local to
regional differences in geology, industrial emissions, and domestic (and cultural) practices, considerable variation results
from the precise means by which bioaccessibility is determined in vitro. It is recommended, therefore, that the effects of
physicochemical variables, and in particular, the solid to fluid ratio and the pH of the stomach phase, are studied systematically
such that appropriate algorithms or corrections may be factored into measures of bioaccessibility obtained under operationally
defined default conditions. |
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