Ecotoxicity of nano-metal oxides: A case study on daphnia magna

Abstract

In Europe REACH framework directive imposes data acquisition concerning toxicity on acquatic species before the commercialization of chemicals to assess environmental risks. According to official methods, exposure tests are performed under in vitro and standardized conditions: OECD's guideline rules external variables such as water type, feeding conditions, and exposure time. As consequence, such obtained results could be different from effects observed in natural environments. This study collects effects within 24-96 h of exposure to nano metal-oxides (ZnO, TiO 2 )onD. magna obtained by the exposure under standard OECD conditions comparing them with results obtained by the exposure under more similar conditions to natural environment (i.e. mixture, feeding). High doses exposure determines gas-bubble disease. Animals exposed to LC10 actively ingest nanoparticles under both fasting and feeding conditions. Furthermore, body burial by a coat of nanoparticles thicker in mixtures than in single dispersions was recorded. Furthermore, results show that: (i) effects increase over time; (ii) n-ZnO results less effective than n-TiO 2 in both single dispersion, and mixture; (iii) the presence of surfactant increases toxicity of nanoparticles; (iv) immobilization is a more sensitive endpoint than mortality; (v) feeding increases test sensitiveness improving differences among treated and controls till 96 h and allowing longer exposure times than standard OECD test. As general remark, this study provides evidence that in vitro ecotoxicological results obtained under standardized OECD conditions could be significant different to animals' responses under natural (feeding and mixtures) exposure conditions.

Environmental Risk Characterization of an Antiretroviral (ARV) Lamivudine in Ecosystems

“…Lower concentrations of lamivudine (10 µg/L) were more toxic with exposure over time, with a 35% increase in mortality over 48 h, whilst higher concentrations had more immediate acute impacts (100 µg/L). Earlier studies assessing the behavioral response of Daphnia magna to nano-metal oxides and chemicals found that daphnids were actively ingesting nanoparticles at feeding and fasting intervals and that chemical concentrations elicited a greater response than the actual structure/toxicity, respectively [30]. The findings in this study corroborate this, with higher concentrations having impacts that are more acute.…”

Nanotechnology‐based wastewater treatment

“…Since the application comes in water management, extra care has to be taken to ensure the safety and efficiency during its implementation. As said before most of the nanomaterials are toxic substances (Baek et al ., 2020; Boyle et al ., 2020, Renzi and Blaskovic, 2019), so there is a possibility of wide erratic outcomes, if they were to be implemented without a proper or elaborative studies. Though the current nanotechnology methodologies for wastewater treatment look promising, more in‐depth research is required to prove their safety.…”

Action of Surfactants in Driving Ecotoxicity of Microplastic-Nano Metal Oxides Mixtures: A Case Study on Daphnia magna under Different Nutritional Conditions

“…Dispersions were made by suspension of tested particles in UNI EN ISO 6341:2012 standard freshwater. Experiments previously reported [28,29] determine for each toxicant the dose permitting the survival of a significant fraction of the tested population until the end of the exposure time (96 h).…”

“…Experimental condition for D. magna (MicroBioTest Inc. ephippia) storage, hatches and preliminary treatments were the same described by Renzi and Blašković [28]. Collection of organisms was standardized at 90 h after the start of incubation.…”

“…All reagents were purchased from Caelo or Sigma-Aldrich. Experimental conditions and sets were the same previously described by Renzi et al [29] and Renzi and Blašković [28] to allow a comparison of reported data on toxicity of mixtures tested in this study with results obtained by previous research on single components of the tested mixtures. Also, experimental conditions are the same to allow a complete comparability of obtained results.…”