The necessity of investigating a freshwater-marine continuum using a mesocosm approach in nanosafety: The case study of TiO2 MNM-based photocatalytic cement

Abstract

Production of Manufactured Nanomaterials (MNMs) has increased extensively due to economic interest in the current years. However, this widespread use raises concern about their impact on human and environment. Current efforts are made, both at national and international levels to help developing safer MNMs in the market. In order to assess hazards of MNMs, it is important to take into account exposome parameters in order to link fate and behavior of MNMs to their potential toxicity. In that context, the aim of this study was to investigate the effects of TiO2 MNMs-based cement at different levels of its life cycle (TiO2MNMs, cement containing TiO2 MNMs) on two exposure mesocosm scenarios mimicking: marine conditions using the bivalve Scrobicularia plana and freshwater conditions using the gastropod Planorbarius corneus for 28 days, allowing measurements of physical-chemical parameters throughout the duration of the exposure. Similar results were observed in both exposure conditions since in the two scenarios Ti was removed from the water column and accumulated in surficial sediments. While in P. corneus, statistically different concentrations of Ti were measured in the digestive glands compared to controls following exposure to TiO2 MNMs, elevated background of Ti concentrations were measured in the controls of S. plana that did not allow to discriminating any bioaccumulation process. In addition, both TiO2 MNMs and TiO2MNM-based cement exposed S. plana did not present any activation of the p38 mitogen-activated protein kinase (MAPKs). This study demonstrates the robustness of using both freshwater and marine mesocosms for evaluation of risk associated with nanomaterial.