Jager T. Worming Your Way Into Bioavailability: Modelling the Uptake of Organic Chemicals in Earthworms

Utrecht University, Institute for Risk Assessment Sciences, Utrecht University), 2003. — 225 p. — ISBN: 903933384X.Bioavailability is a complicated issue. In this thesis, Tjalling Jager discusses how organic chemicals are taken up by earthworms, and to what extent. Earthworms are essential for soil fertility, as well as important dietary items for a range of predators. A "mechanistic" approach is followed: starting with the theory, translating theory into mathematical models, and experiments to verify the model predictions.
This process leads to a broad evaluation of the equilibrium-partitioning (EP) theory, and a quantification of the different routes by which chemicals are taken up into earthworms. The work in this thesis shows that risk assessment can safely rely on EP predictions (at least for worst-case estimates).This thesis contains 11 chapters, of which 8 have been published in the scientific literature. Apart from the introduction and general discussion, especially the unpublished Chapter 2 may be of interest. This chapter provides a in-depth explanation of compartment modeling for toxicokinetics, departing from the basics (the one-compartment model and the nature of the rate constants) and moving to model extensions to deal with deviating kinetics and bioavailability issues. This chapter is written 'text-book style', and forms a good introduction into TK modeling.General Introduction
Section A: Theoretical
Using Compartment Models for Bioaccumulation
Mechanistic Approach for Estimating Bioconcentration of Organic Chemicals in Earthworms (Oligochaeta)
Section B: Case Studies
Toxicokinetics of Polycyclic Aromatic Hydrocarbons in Eiseniaandrei (Oligochaeta) using Spiked Soil
Availability of Polycyclic Aromatic Hydrocarbons to Earthworms (Eisenia andrei, Oligochaeta) in Field-Polluted Soils and Soil-Sediment Mixtures
Assessing Bioavailability of Organic Chemicals in Contaminated Soils, Evaluation of Bioassays with Earthworms
Solid Phase MicroExtraction to Predict Bioavailability and Accumulation in a Field-ontaminated Soil
Section C: Gut Uptake
Modeling Ingestion as an Exposure Route for Organic Chemicals in Earthworms (Oligochaeta)
Feeding Activity of the Earthworm Eisenia andrei in Artificial Soil
Elucidating the Routes of Exposure for Organic Chemicals in the Earthworm, Eisenia andrei (Oligochaeta)
Summary and General Discussion