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Proceedings: ISEA Bioavailability Symposium, Durham, North Carolina Use of InVitro Bioaccessibility/Relative Bioavailability Estimates for Metals in Regulatory Settings: What is Needed?
Citation:
BRADHAM, K. D., M. BERINGER, AND A. YEOW. Proceedings: ISEA Bioavailability Symposium, Durham, North Carolina Use of InVitro Bioaccessibility/Relative Bioavailability Estimates for Metals in Regulatory Settings: What is Needed? ISEA Bioavailability Symposium , Durham, NC, October 14 - 18, 2007. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-08/102 (NTIS PB2008-113476), 2008.
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA′s mission to protect human health and the environment. HEASD′s research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA′s strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools are improved regulatory programs and policies for EPA.
Description:
Oral ingestion of soil and dust is a key pathway for human exposures to metal and metalloid contaminants. It is widely recognized that the site-specific bioavailability of metals in soil and dust may be reduced relative to the metal bioavailability in media such as water and food, and adjustments for oral relative bioavailability are becoming more accepted. Both animal models and in vitro bioaccessibility models have been used to estimate relative bioavailability of metals in soil and dust. Although animal models are often considered the "gold standard", they may be costly or otherwise prohibitive at certain sites and may not be sensitive enough to test environmentally relevant samples for all contaminants. Routine application of in vitro metal bioaccessibility models in regulatory settings is being held up by different perceptions of what is required of these models in terms of validation. This symposium provided the opportunity for international experts to exchange their views on methods for assessing relative bioavailability/bioaccessibility for application in risk assessments at contaminated sites. The symposium speakers presented recent developments in animal models, new in vitro models, the role of mineralogical analyses in assessing relative bioavailability, and the application of physiologically based models as research tools. In addition, two panel discussions addressed specific research questions and discussed future research needs in this area. Recognizing the multi-disciplinary nature of exposure assessment, this symposium included representation from many disciplines including risk assessment, toxicology, environmental geochemistry, geology, soil, and analytical chemistry from the U.S., Europe, and Canada.