Exposure Through Soil and Dust Ingestion - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 261

Chapter 6
Exposure Through Soil and Dust Ingestion

Johan Bierkens, Mirja Van Holderbeke, Christa Cornelis, and Rudi Torfs

Abstract The current chapter discusses soil and dust ingestion, a potentially impor-
tant pathway for non-dietary oral exposure, especially for children. Starting from
clear definitions on what is meant by soil and dust and how they interrelate, it
explores the several approaches that have been used to derive estimates of soil
and dust ingestion rates. It concludes that tracer methodology studies, with all their
limitations and uncertainties, probably provide the most adequate estimates of soil
ingestion rates. However, these studies are limited to short-term estimates and do
not distinguish between soil and dust. Hand-loading studies can be designed so that
information is collected for the micro-environments we are interested in, but the
interpretation requires assumptions about transfer parameters, which may introduce
substantial uncertainty. Biokinetic modelling studies only provide rough estimates
or ranges of estimates, but are nevertheless useful as a complementary line of evi-
dence. From a comparison of these approaches it is concluded that average soil and
dust ingestion rates for children are below 100 mg/d and most likely around 50 mg/d,
a conclusion that is confirmed by the most recent evaluations published in literature.
Still, good estimates of site-specific soil and dust ingestion rates for Europe are lack-
ing due to paucity of data on age-related time activity patterns, transfer factors and
intrinsic differences in children's behaviour.

Contents

6.1 Introduction ............................................ 262

6.1.1 General Aspects ..................................... 262

6.1.2 Defining Soil and Dust .................................

262

6.1.3 Calculating Exposure Through Ingestion of Soil and Dust ............

264

6.2 Quantification of Soil and Dust Ingestion Rates ...................... 265