About the Book
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 Apart from the introduction and general discussion, especially the unpublished Chapter 2 may be of interest.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 modelling 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 modelling.
This book is my PhD thesis from 2003, and there will be no updates.
About the Author
Mechanistic modelling is still an under-utilised tool in ecotoxicology and stress ecology. It is my passion to promote these models through (applied) scientific projects, providing software solutions, teaching in courses, presentations at conferences, and through writing e-books. The models that I specialise in are so-called toxicokinetic-toxicodynamic (TKTD) models; in particular, models for survival (the GUTS framework) and sublethal effects (based on Dynamic Energy Budget - DEB - theory). These models are based on a rigorous simplification of biological complexity, and have the power to explain (and predict) life-history traits of organisms (e.g., growth, reproduction and survival) over time. Especially when considering exposure to stressors, such dynamic models are indispensable to make sense of the data.
I hold an MSc and PhD in Biology, and have been a professional modeller since 1992, working almost exclusively on DEB- and GUTS-based TKTD modelling since 2002. Currently, I run my own private company 'DEBtox Research', offering my expertise to clients from industry, contract laboratories, and universities.