Toxicokinetic and toxicodynamic modeling explains carry-over toxicity from exposure to diazinon by slow organism recovery

Ashauer, R., Hintermeister, A., Caravatti, I., Kretschmann, A. and Escher, B. I. (2010). Toxicokinetic and toxicodynamic modeling explains carry-over toxicity from exposure to diazinon by slow organism recovery. In: SETAC Europe 20th Annual Meeting, Seville, Spain, (). 23-27 May 2010.

Author Ashauer, R.
Hintermeister, A.
Caravatti, I.
Kretschmann, A.
Escher, B. I.
Title of paper Toxicokinetic and toxicodynamic modeling explains carry-over toxicity from exposure to diazinon by slow organism recovery
Conference name SETAC Europe 20th Annual Meeting
Conference location Seville, Spain
Conference dates 23-27 May 2010
Publisher Society of Environmental Toxicology and Chemistry (SETAC)
Publication Year 2010
Sub-type Published abstract
ISBN not found
Language eng
Formatted Abstract/Summary
Carry-over toxicity occurs when organisms exposed to an environmental toxicant survive but carry some damage resulting in reduced fitness. Upon subsequently encountering another exposure event stronger effects are possible if the organisms have not yet fully recovered. Carry-over toxicity was observed after exposure of the freshwater amphipod Gammarus pulex to repeated pulses of diazinon with varying intervals. Uptake, biotransformation and depuration kinetics were determined in independent experiments. Metabolites were identified and quantified (diazoxon, 2-isopropyl-6-methyl-4-pyrimidinol, one non-identified metabolite). Parameters of a process-based toxicokinetic-toxicodynamic model were determined by least-square fitting followed by Markov Chain Monte Carlo parameter estimation. Model parameterization was based on the time-course of measured internal concentrations of diazinon and its metabolite diazoxon in combination with the pulsed toxicity experiment. Prediction intervals, which take the covariation between parameters into account, were calculated for bioconcentration factors, organism recovery time and simulations of internal concentrations as well as the time-course of survival under variable exposure. Organism recovery time was 31 days [95% prediction interval 26 - 36 days], indicating the possibility for carry-over toxicity from exposure events several weeks apart. The slow organism recovery and carry-over toxicity was caused by slow toxicodynamic recovery, toxicokinetic processes could not account for these observations.
Subjects 030104 Immunological and Bioassay Methods
Keyword Delayed toxicity
Ecotoxicology
Risk assessment
Temporal extrapolation
Q-Index Code EX
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Presented as paper ET05-2 during "ET05 - Hazard, exposure and risk assessment of pesticides, biocides and their mixtures".

 
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