Abstract
Complexity of contaminants exposure needs to be taking in account for an appropriate evaluation of risks related to mixtures of pesticides released in the ecosystems. Toxicity assessment of such mixtures can be made through a variety of toxicity tests reflecting different level of biological complexity. This paper reviews the recent developments of passive sampling techniques for polar compounds, especially Polar Organic Chemical Integrative Samplers (POCIS) and Chemcatcher® and the principal assessment techniques using microalgae in laboratory experiments. The progresses permitted by the coupled use of such passive samplers and ecotoxicology testing as well as their limitations are presented. Case studies combining passive sampling devices (PSD) extracts and toxicity assessment toward microorganisms at different biological scales from single organisms to communities level are presented. These case studies, respectively, aimed (i) at characterizing the “toxic potential” of waters using dose-response curves, and (ii) at performing microcosm experiments with increased environmental realism in the toxicant exposure in term of cocktail composition and concentration. Finally perspectives and limitations of such approaches for future applications in the area of environmental risk assessment are discussed.
Highlights
Aquatic organisms are exposed to a large variety of natural and anthropogenic stressors
Effect of various toxicant at concentrations closed to environmental contamination levels have been studied; on microcosms or channels systems; on biofilms (Pérès et al, 1996; Gold et al, 2003; Schmitt-Jansen and Altenburger, 2005; Pesce et al, 2006; Morin et al, 2008b, 2010, 2012b; Tlili et al, 2008, 2011c; Debenest et al, 2009; Ricart et al, 2009; Serra and Guasch, 2009; Corcoll et al, 2011; Roubeix et al, 2011a; Bonnineau et al, 2012; Barral-Fraga et al, 2016) and on phytoplanktonic assemblages (Fisher et al, 1974; Gustavson and Wängberg, 1995; Wallen, 1996; Seguin et al, FIGURE 1 | Illustration of a dose-response curve with the half maximal Effective Concentration (EC50), the No Observed Effect Concentration (NOEC), and the Lowest Observed Effect Concentration (LOEC)
Classical approaches in mixture toxicity consist in using models incremented with data obtained from single compound toxicity tests, these approaches permit to apprehend the relations of additivity, antagonism or synergism occurring in the mixture but are restricted to mixtures containing a very limited number of substances which are poorly representative of environmental contamination
Summary
Aquatic organisms are exposed to a large variety of natural and anthropogenic stressors. Recent developments of passive sampling techniques allowed, (i) to better consider the diversity of co-occurring substances in the environment, (ii) to lower their detection limits, and (iii) to focus on the freely dissolved fraction instead of the total amount of contaminants, which is more comparable to the in situ bioavailability These advantages of passive sampling compared to spot sampling relied on the capacity of the device to accumulate contaminants over a defined period of time. Biofilm-based ecotoxicology increases the predictive power of impacts at the ecosystem scale, compared to the extrapolation of results disconnected from the natural complexity (diversity of organisms and of their relations) These communities are used successfully in ecotoxicology, in the laboratory or in situ, to assess impacts of diverse contaminants (e.g., Guasch et al, 2012). The determination of the ecotoxicity of complex mixtures of toxicants could hardly be achieved this way, given the multiplicity of possible cocktails (in terms of composition, and concentrations), preventing to test all the combinations likely to be found in situ
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