A Bayesian framework for estimating parameters of a generic toxicokinetic model for the bioaccumulation of organic chemicals by benthic invertebrates: Proof of concept with PCB153 and two freshwater species

Abstract

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New perspectives on the calculation of bioaccumulation metrics for active substances in living organisms

“…For simplicity reasons, in MOSAIC bioacc , the choice of priors is hidden to the user with no possibility to change them. To keep priors the most generic as possible, they were assumed following a non-informative (−5, 5) log10-uniform distribution for all uptake and elimination rate constants, and a non-informative (0.001, 0.001) Gamma distribution for all standard deviations, as usually done in the field of bioaccumulation studies (Lambert et al, 2005; Ratier et al, 2019; Richards and Chaloupka, 2009).…”

“…Thanks to rjags, model parameters are retrieved as a joint posterior distribution from the likelihood of the observed data combined with prior distributions on parameters. All details on this approach can be found in the original research paper (Ratier et al, 2019) but also in many other papers in the field of ecotoxicology (Billoir et al, 2011; Ockleford et al, 2018).…”

“…Its purpose is to facilitate the daily work of regulators, but also of any user, benefiting of a freely available and user-friendly interface avoiding to invest into underlying statistical and technical aspects. This web tool clearly takes advantage of the new conceptual framework developed by Ratier et al (2019) in order to estimate parameters of a one-compartment TK model as a whole including several exposure routes (water, food, sediment), accounting for metabolization of the chemical substance and possibly for growth dilution. The use of MOSAIC bioacc will only require to upload standard experimental data, then some clicks to get all the results.…”

“…Besides, regulators are sceptical about the diversity and complexity of the possible methods and tools to use and run TK models, while thinking about their standardization at the same time (Tan et al 2020). Ratier et al (2019) recently proposed a full revisit of the approach based on a unified inference method to estimate parameters of TK models for both accumulation and depuration phases, simultaneously. This innovative framework has been thought to make it possible to further incorporate the TK part into complete TKTD models.…”

“…The present paper presents new perspectives on the calculation of bioaccumulation factors (BCF/BSAF/BMF) via a new ready-to-use web tool, MOSAIC bioacc , leading to the estimation of bioaccumulation factors automatically associated with their uncertainty in full compliance with the new framework from Ratier et al (2019). The purpose is to facilitate the daily work of regulators, but also of any user, benefiting of a freely available user-friendly interface avoiding to invest into mathematical and statistical underlying technical aspects.…”