Little Simon, Johnston Helinor J, Stone Vicki, Fernandes Teresa F
Institute of Life and Earth Sciences, School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
NanoImpact. 2021 Jan;21:100291. doi: 10.1016/j.impact.2020.100291. Epub 2021 Jan 22.
The use of silver (Ag) and titanium dioxide (TiO) nanomaterials (NMs) in industrial processes and consumer products has experienced considerable growth since the late 20th century. Throughout their lifecycle, both Ag NM and TiONM are released into the environment, with benthic systems anticipated to be the final sink. Their potential toxicity towards benthic species is therefore of major concern. This study investigated the toxicity of silver (Ag; NM-300 K) and titanium dioxide (TiO; NM-104) NMs to the freshwater oligochaete, Lumbriculus variegatus in acute (0-96-h) waterborne and chronic (28-d) sediment studies. Toxicity was investigated via assessment of mortality, behaviour, and antioxidant enzyme activity. The 96-h LC for Ag NMs in water was 0.51 mg/l (95% CI, 0.45-0.56), with L. variegatus displaying inhibited predation-avoidance behaviour compared to controls (6.66 ± 10%) successful response at 24-h), as well as significant increases (p < 0.05) in catalase (CAT) activity at sub-lethal concentrations at 24-h. Behavioural improvement and the return of antioxidant enzymes to control levels was observed after 48 and 72-h. AgNO exposure proved more toxic than Ag NM (96-h LC = 0.034 mg/l, 95% CI, 0.031-0.037) but resulted in no changes to antioxidant enzymes following sub-lethal exposure. Furthermore, Ag dissolution from Ag NM (~2-4%) could not account for the full extent of toxicity observed, suggesting a nano-specific effect. Increased environmental relevance via the inclusion of Suwannee River Humic Acid (SRHA, 5 mg/l) alleviated sub-lethal Ag NM toxicity despite a comparable 96-h LC (0.54 mg/l, 95% CI, 0.51-0.57). Significant effects of Ag NMs in formulated sediments (mortality, biomass) were only recorded according to OECD 225 at the highest test concentration (1333 mg/kg) for Ag NM indicating a potential attenuating effect of sediments towards toxicity. No toxicity was observed for TiO NM in aquatic or sediment exposures up to concentrations of 2000 mg/l and 1333 mg/kg, respectively.
自20世纪末以来，银（Ag）和二氧化钛（TiO₂）纳米材料（NMs）在工业生产过程和消费品中的使用量大幅增长。在其整个生命周期中，Ag纳米材料和TiO₂纳米材料都会释放到环境中，预计底栖系统将是它们的最终归宿。因此，它们对底栖生物的潜在毒性备受关注。本研究通过急性（0 - 96小时）水体暴露和慢性（28天）沉积物暴露实验，研究了银（Ag；NM - 300K）和二氧化钛（TiO₂；NM - 104）纳米材料对淡水寡毛类动物颤蚓（Lumbriculus variegatus）的毒性。通过评估死亡率、行为和抗氧化酶活性来研究毒性。水中Ag纳米材料的96小时半数致死浓度（LC₅₀）为0.51毫克/升（95%置信区间，0.45 - 0.56），与对照组相比，颤蚓的捕食回避行为受到抑制（24小时时对照组成功反应率为6.66 ± 10%），并且在24小时亚致死浓度下过氧化氢酶（CAT）活性显著增加（p < 0.05）。在48小时和72小时后观察到行为改善以及抗氧化酶活性恢复到对照水平。硝酸银（AgNO₃）暴露的毒性比Ag纳米材料更大（96小时LC₅₀ = 0.034毫克/升，95%置信区间，0.031 - 0.037），但亚致死暴露后抗氧化酶没有变化。此外，Ag纳米材料中Ag的溶出率约为2 - 4%，无法完全解释所观察到的毒性程度，表明存在纳米特异性效应。通过添加苏万尼河腐殖酸（SRHA，5毫克/升）增加环境相关性，尽管96小时LC₅₀相当（0.54毫克/升，95%置信区间，0.51 - 0.57），但减轻了亚致死Ag纳米材料的毒性。仅在根据经合组织225标准的最高测试浓度（1333毫克/千克）下，才记录到Ag纳米材料在配制沉积物中产生显著影响（死亡率、生物量），表明沉积物对毒性具有潜在的衰减作用。在水生暴露或沉积物暴露中，分别高达2000毫克/升和1333毫克/千克的浓度下，未观察到TiO₂纳米材料的毒性。
