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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, TiO2) on D. 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-TiO2 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.
摘要：
在欧洲，REACH框架指令规定在化学品商业化之前采集有关水生物种毒性的数据，以评估环境风险。根据官方方法,暴露测试在体外和标准化条件下进行：OECD的指南规则外部变量，如水类型，喂养条件,和曝光时间。因此，这样获得的结果可能与自然环境中观察到的效果不同。本研究收集了暴露于纳米金属氧化物(ZnO，TiO2）在标准OECD条件下通过暴露获得的D.magna上，将它们与在更相似的条件下暴露于自然环境（即混合物，feeding).高剂量暴露决定了气泡疾病。暴露于LC10的动物在禁食和进食条件下都会主动摄取纳米颗粒。此外，记录了在混合物中比在单一分散体中更厚的纳米颗粒涂层的身体埋葬。此外，结果表明：（i）效果随时间增加；（ii）在两种单一分散中，n-ZnO的效果均低于n-TiO2，和混合物；（iii）表面活性剂的存在增加了纳米颗粒的毒性；（iv）固定化是比死亡率更敏感的终点；（v）喂食增加了测试敏感性，改善了治疗和对照之间的差异，直到96小时，并且允许比标准OECD测试更长的暴露时间。作为一般性评论，本研究提供的证据表明,在标准化OECD条件下获得的体外生态毒理学结果可能与动物在自然(摄食和混合)暴露条件下的反应显著不同.
