Environmental Engineering Reference
In-Depth Information
Chapter 7
Oral Bioavailability
Mark R. Cave, Joanna Wragg, Sébastien Denys, Catherine Jondreville,
and Cyril Feidt
Abstract Soil ingestion is a key exposure pathway in Human Health Risk
Assessment for contaminants in soil. The theory and mechanisms of how contami-
nants in a soil enter the human body through the gastrointestinal tract are outlined.
The methods available for measuring human exposure using human, animal and
validated in-vitro laboratory methods are described and contrasted. The role of
the physico-chemical properties of the soils that control the bioavailability of con-
taminants are summarised. Finally, examples of how bioavailability/bioaccessibility
studies of soils from both anthropogenic and geogenic origin are discussed along
with the criteria required for deciding whether bioavailability data should be used
in a Human Health Risk Assessment.
Contents
7.1 Theory of Availability ......................................
288
7.1.1 Oral Bioavailability ...................................
289
7.1.2 Relative Bioavailability Factor .............................
296
7.1.3 Validation of Bioaccessibility Tests ..........................
299
7.2 Influence of Soil Properties on Oral Bioaccessibility ...................
300
7.2.1 pH ..............................................
300
7.2.2 Soil Organic Matter ...................................
300
7.2.3 Mineral Constituents ..................................
301
7.2.4 Solid Phase Speciation and Bioaccessibility ....................
305
7.2.5 Soil Ageing ........................................
306
7.2.6 Statistical Modelling of Bioaccessibility .......................
306
7.2.7 Soil Sampling and Preparation for Bioaccessibility/Bioavailability
Measurements .......................................
307
7.3 Considerations for the Potential Use of Site Specific Bioaccessibility Measurements
308
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