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Comparison of five in vitro digestion models to in vivo experimental results: Lead bioaccessibility in the human gastrointestinal tract

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Author: Wiele, T.R. van de · Oomen, A.G. · Wragg, J. · Cave, M. · Minekus, M. · Hack, A. · Cornelis, C. · Rompelberg, C.J.M. · Zwart, L.L. de · Klinck, B. · Wijnen, J. van · Verstraete, W. · Sips, A.J.A.M.
Type:article
Date:2007
Institution: TNO Kwaliteit van Leven
Source:Journal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering, 9, 42, 1203-1211
Identifier: 239786
doi: doi:10.1080/10934520701434919
Keywords: Biomedical Research · Bioaccessibility · Bioavailable · Human gut · In vitro digestion · Intestine · Pb · Soil ingestion · Approximation algorithms · Biological organs · Computer simulation · Lead · Optimization · Risk assessment · Separation · Soils · Bioaccessibility · Bioavailability · Gastrointestinal tract · Human gut · In vitro digestion · Soil ingestion · Physiological models · lead · article · bioavailability · centrifugation · comparative study · diet restriction · digestion · filtration · food intake · gastrointestinal tract · in vitro study · lead poisoning · simulation · soil analysis · ultrafiltration · Biological Availability · Data Interpretation, Statistical · Gastrointestinal Tract · Humans · Lead · Models, Biological · Soil · Soil Pollutants

Abstract

This paper presents a multi-laboratory comparison study of in vitro models assessing bioaccessibility of soil-bound lead in the human gastrointestinal tract under simulated fasted and fed conditions. Oral bioavailability data from a previous human in vivo study on the same soil served as a reference point. In general, the bioaccessible lead fraction was significantly (P < 0.05) different between the in vitro methods and ranged for the fasted models from 2% to 33% and for the fed models from 7% to 29%. The in vivo bioavailability data from literature were 26.2 ± 8.1% for fasted conditions, compared to 2.5 ± 1.7% for fed conditions. Under fed conditions, all models returned higher bioaccessibility values than the in vivo bioavailability; whereas three models returned a lower bioaccessibility than bioavailability under fasted conditions. These differences are often due to the method's digestion parameters that need further optimization. An important outcome of this study was the determination that the method for separating the bioaccessible lead from the non-bioaccessible fraction (centrifugation, filtration, ultrafiltration) is crucial for the interpretation of the results. Bioaccessibility values from models that use more stringent separation methods better approximate in vivo bioavailability results, yet at the expense of the level of conservancy. We conclude from this study that more optimization of in vitro digestion models is needed for use in risk assessment. Moreover, attention should be paid to the laboratory separation method since it largely influences what fraction of the contaminant is considered bioaccessible. Copyright © Taylor & Francis Group, LLC.