Mixture toxicity of phostebupirim and cyfluthrin: Species‐specific responses

Abstract

Currently, the potential impact of insecticide mixtures to nontarget organisms is largely unknown, and additional study is needed. The present study investigated the mixture toxicity of the organophosphate insecticide phostebupirim and the pyrethroid insecticide cyfluthrin using 4 nontarget species including Daphnia magna, Hyalella azteca, Pimephales promelas (fathead minnow), and Danio rerio (zebrafish). For each species, the toxicity of equipotent mixtures was compared with the expected toxicity estimated using the independent action (IA) and concentration addition (CA) models. Lethal and sublethal responses to D. magna and H. azteca were best described with the IA model. For both fish species, mixture toxicity was significantly higher than that estimated using either mixture model. The synergism noted in fish exposed to the combination of phostebupirim and cyfluthrin was confirmed by exposing P. promelas larvae to a nontoxic dose of phostebupirim and a range of toxic cyfluthrin concentrations, and vice versa. Sublethal and lethal concentrations to fish were up to 7 times lower for the mixture than in concurrently run individual compound exposures. Potential mechanisms for the synergistic responses found in fish are presented. Environ Toxicol Chem 2017;36:1947-1954. © 2016 SETAC.

A critical review of effect modeling for ecological risk assessment of plant protection products

“…This tool hts ecotoxicity data to the conceptual models (CA or IA) and then évaluâtes if there are any déviations for synergism/antagonism or dose level or ratio dependencies (i.e., depending on low or high doses, or dépendent on the ratio of the Chemicals in the mixture, respectively). In the same way, the Model Déviation Ratio (MDR) technique is used to détermine the biological signihcance and reproducibility of observed mixture effects (e.g., Belden et al 2007;Lopez Aca et al 2018;De Perre et al 2017;Belden and Brain 2018;Lanteigne et al 2015) by comparing predicted and observed results of mixture toxicity. If the MDR values are < 5, then the CA model applies since the additive MoA can be assumed.…”

The use of integrative approaches to characterize new mechanisms of toxicity of pollutants in the aquatic environment

“…Furthermore, compounds that affect specific organisms or sensitive life-stages and compounds known to interact with highly conserved targets across taxas e.g. pharmaceuticals, may also represent a special concern (de Perre et al, 2016;Jager et al, 2016;Vasquez et al, 2014). Under this perspective, it is evident that there is no "one-size-fits-all" ecotoxicological bioassay that can be used to comprehensively assess the effects of complex mixtures of chemicals in the environment.…”