Chronic toxicity of core–shell SiC/TiO2 (nano)-particles to Daphnia magna under environmentally relevant food rations in the presence of humic acid
Publication category: Journal Article
Publication date: February 29, 2024
Authors: Serwatowska, K.J.; Nederstigt, T.A.P.; Peijnenburg W.J.G.M.; Vijver M.G.
Abstract: To date, research on the toxicity and potential environmental impacts of nanomaterials has predominantly focused on relatively simple and single-component materials, whilst more complex nanomaterials are currently entering commercial stages. The current study aimed to assess the long-term and size-dependent (60 and 500nm) toxicity of a novel core–shell nanostructure consisting of a SiC core and TiO2 shell (SiC/TiO2, 5, 25, and 50mg L−1) to the common model organism Daphnia magna. These novel core–shell nanostructures can be categorized as advanced materials. Experiments were conducted under environmentally realistic feeding rations and in the presence of a range of concentrations of humic acid (0.5, 2, 5, and 10mg L−1 TOC). The findings show that although effect concentrations of SiC/TiO2 were several orders of magnitude lower than the current reported environmental concentrations of more abundantly used nanomaterials, humic acid can exacerbate the toxicity of SiC/TiO2 by reducing aggregation and sedimentation rates. The EC50 values (mean±standard error) based on nominal SiC/TiO2 concentrations for the 60nm particles were 28.0±11.5mg L−1 (TOC 0.5mg L−1), 21.1±3.7mg L−1 (TOC 2mg L−1), 18.3±5.4mg L−1 (TOC 5mg L−1), and 17.8±2.4mg L−1 (TOC 10mg L−1). For the 500nm particles, the EC50 values were 34.9±16.5mg L−1 (TOC 0.5mg L−1), 24.8±5.6mg L−1 (TOC 2mg L−1), 28.0±10.0mg L−1 (TOC 5mg L−1), and 23.2±4.1mg L−1 (TOC 10mg L−1). We argue that fate-driven phenomena are often neglected in effect assessments, whilst environmental factors such as the presence of humic acid may significantly influence the toxicity of nanomaterials.
