Explicit Consideration of Temperature Improves Predictions of Toxicokinetic–Toxicodynamic Models for Flupyradifurone and Imidacloprid in Gammarus pulex

Abstract

In the face of global climate change, where temperature fluctuations and the frequency of extreme weather events are increasing, it is needed to evaluate the impact of temperature on the ecological risk assessment of chemicals. Current state-of-the-art mechanistic effect models, such as toxicokinetic–toxicodynamic (TK–TD) models, often do not explicitly consider temperature as a modulating factor. This study implemented the effect of temperature in a widely used modeling framework, the General Unified Threshold model for Survival (GUTS). We tested the model using data from toxicokinetic and toxicity experiments with Gammarus pulex exposed to the insecticides imidacloprid and flupyradifurone. The experiments revealed increased TK rates with increasing temperature and increased toxicity under chronic exposures. Using the widely used Arrhenius equation, we could include the temperature influence into the modeling. By further testing of different model approaches, differences in the temperature scaling of TK and TD model parameters could be identified, urging further investigations of the underlying mechanisms. Finally, our results show that predictions of TK–TD models improve if we include the toxicity modulating effect of temperature explicitly.

Elimination Resistance: Characterizing Multi-compartment Toxicokinetics of the Neonicotinoid Thiacloprid in the Amphipod Gammarus pulex Using Bioconcentration and Receptor-Binding Assays

“…Furthermore, it should be noted that similar molar concentrations of imidacloprid at the end of the elimination phase from toxicokinetic experiments with two other G. pulex populations , were comparable to the observations for thiacloprid in the present study. These findings support the suggested similar nAChR-binding capabilities of the two neonicotinoids in gammarids.…”

“…Such considerations may be important for the risk assessment of neonicotinoids, as well as their replacement candidates (i.e., flupyradifurone 9 ) and other contaminants with (irreversible) receptor-binding properties. Furthermore, existing TK−TD modeling approaches 19,49,54,55 may be updated based on the present findings. The standard bioaccumulation assessment, according to OECD 305 25 using fish, generally assumes one-compartment kinetics, an independence of bioaccumulation parameters from exposure concentrations and a relevance of bioaccumulation only for compounds with high log K OW values.…”

“…Such considerations may be important for the risk assessment of neonicotinoids, as well as their replacement candidates (i.e., flupyradifurone) and other contaminants with (irreversible) receptor-binding properties. Furthermore, existing TK–TD modeling approaches ,,, may be updated based on the present findings.…”

Speed it up: How temperature drives toxicokinetics of organic contaminants in freshwater amphipods

“…Alternatively, toxicokinetic–toxicodynamic models including temperature corrections (i.e. Arrhenius based) have been successfully used recently to analyse temperature‐dependent toxicity directly, but thereby reducing mechanistic toxicokinetic information (Goussen et al, 2020 ; Mangold‐Döring et al, 2022 ; Rakel et al, 2022 ).…”

“…Important toxicokinetic parameters are uptake, elimination and biotransformation rates as well as the bioconcentration factor (BCF, ratio of internal and exposure concentration under equilibrium conditions). Systematic investigations on the impact of temperature on toxicokinetics, such as determination of toxicokinetic rates or assuring equilibrium conditions, are rare (Dai et al, 2021 ; Mangold‐Döring et al, 2022 ). Furthermore, contrasting results such as higher (Buchwalter et al, 2003 ; Camp & Buchwalter, 2016 ; Dai et al, 2021 ; Nawaz & Kirk, 1996 ) (caddisfly, stonefly, mayfly, earthworm, daphnids), indifferent (Cerveny et al, 2021 ; Kuo & Chen, 2021 ) (fish, midge) or lower (Brown et al, 2021 ; Muijs & Jonker, 2009 ) (frog, aquatic worm) internal contaminant concentrations at higher temperatures are reported in ectothermic aquatic organisms.…”