PRINCIPLES OF ENVIRONMENTAL TOXICOLOGY AND CONTAMINATION (PART II)

Table of Contents

1. Index
2. UNIT 5 - Transport and fate of contaminants in the environment
3. UNIT 6 - Principles of toxicokinetics and toxicodynamics
   1. Introduction
   2. Toxicokinetics
   3. Factors that affect toxicity: Species Differences
   4. Toxicokinetic and toxicodynamic models
4. UNIT 7 - Biotransformation
5. UNIT 8 - Toxicity Testing
6. Glossary of key terms associated with environmental toxicology

Toxicokinetic and toxicodynamic models

Toxicokinetic-toxicodynamic (TK-TD) models simulate the processes that lead to toxicity at the level of organisms over time. These dynamic simulation models quantify toxicity, but more importantly they also provide a conceptual framework to better understand the causes for different toxicity of different compounds to the same species as well as causes for variability in different species' sensitivity to the same compound. A simple and illustrative example of TK-TD modelling, where internal concentration (TK) and the damage (TD) are simulated in response to exposure, is depicted in figure 4.

Figure 4 - Dynamic simulation of processes causing toxicity and their grouping into toxicokinetics and toxicodynamics, illustrated by the example of the aquatic invertebrate Gammarus pulex. Source: Ashauer and Escher (2010).

More information on toxicokinetic and toxicodynamic models can be found in the following link and papers:

http://www.ecotoxmodels.org/toxicokinetic-toxicodynamic-models/

REFERENCES

Ashauer R, Escher BI. (2010). Advantages of toxicokinetic and toxicodynamic modelling in aquatic ecotoxicology and risk assessment. Journal of Environmental Monitoring 12: 2056-2061.

Bartelme TD. (2006). Feature Article: Metabolism, Energy Use and Feeding Behaviors in Fish. Advanced aquarist. Available at: http://www.advancedaquarist.com/2006/4/aafeature1

European Chemicals Agency. (2014). Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.7c: Endpoint specific guidance. 260p. Available at: https://echa.europa.eu/documents/10162/13632/information_requirements_r7c_en.pdf

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Nordberg GF, Fowler BA, Nordberg M. (2015). Handbook on the toxicology of metals. 4^th edition. Academic Press, London, UK. 1542p.

Ran GM. (1995). Fundamentals of aquatic toxicology: Effects, environmental fate and risk assessment. 2^nd Edition. CRC Press, London, UK. 1148p.

Robinson L, Thorn I. (2005). Toxicology and ecotoxicology in chemical safety assessment. Blackwell Publishing Ltd., Oxford, UK. 157p.

Skip B, Bednarska AJ, Laskowski R. (2014). Toxicokinetics of metals in terrestrial invertebrates: Making things straight with the one-compartment principle. PLoS ONE 9(9): e108740. doi:10.1371/journal.pone.0108740

Stelljes ME. (2008). Toxicology for Non-toxicologists. 2^nd edition. The Scarecrow Press, Inc, Lanham, Maryland, USA. 207p.

Williams PL, James RC, Roberts SM. (2000). Principles of toxicology. Environmental and Industrial Applications. 2^nd edition. John Wiley & Sons, Inc., New York, USA. 603p.