Centre for Functional Ecology (CFE), Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
Faculty of Biology Alexandru Ioan Cuza, University of Iași, Romania.
Sci Total Environ. 2022 Feb 1;806(Pt 1):150491. doi: 10.1016/j.scitotenv.2021.150491. Epub 2021 Sep 23.
Polymethylmethacrylate (PMMA) production has increased almost 20% over the last years. With its release into the aquatic environment, its breakdown or degradation to nano dimensions (nanoplastics-NPLs) due to biological and physical/mechanical action is, theoretically, anticipated. The occurrence of PMMA-NPLs in aquatic ecosystems may thus cause adverse effects particularly to early life stages of amphibians, which may be in contact with PMMA-NPLs suspended in the water column or deposited in upper layers of the sediments. Accordingly, this work aimed at assessing the effects of PMMA-NPLs to aquatic early life stages of the model anuran species Xenopus laevis. To attain this objective, two types of toxicity assays were carried out by exposing embryos [Nieuwkoop and Faber (NF) stage 8-11] or tadpoles (NF 45) to three concentrations of PMMA-NPLs (1, 100 and 1000 μg/L): i) 96-h embryo teratogenicity assay, where survival, malformation, and total body length (BL) of embryos were assessed; and ii) 48-h feeding rate assay, where survival, feeding (FR), malformations and growth rates (body weight-BW and BL) of tadpoles were evaluated. PMMA-NPLs exposure had no significant effects on mortality, malformations of X. laevis embryos but BL was lower at 1000 μg PMMA-NPLs/L. In tadpoles, no effects on survival or FR were observed after exposure to PMMA-NPLs, but significant changes occured in BW and BL. Moreover, anatomical changes in the abdominal region (externalization of the gut) were observed in 62.5% of the tadpoles exposed to 1000 μg PMMA-NPLs/L. Despite the lack of knowledge regarding the environmental levels of NPLs, it is expected that sediments constitute a sink for these contaminants, where they can become available for organisms that, like tadpoles, feed on the organic matter at the surface of sediments. Considering the continuous release and subsequent accumulation of PMMA, the malformations obtained in the feeding assays suggest that, in the future, these nano-polymers may constitute a risk for aquatic life stages of amphibians.
聚甲基丙烯酸甲酯（PMMA）的产量在过去几年中增长了近 20%。由于生物和物理/机械作用，PMMA 被释放到水生环境中，其分解或降解为纳米尺寸（纳米塑料-NPLs）是理论上可以预期的。PMMA-NPLs 在水生生态系统中的出现可能会对两栖动物的早期生命阶段产生不利影响，这些生命阶段可能会接触到悬浮在水柱中的 PMMA-NPLs 或沉积在沉积物上层的 PMMA-NPLs。因此，这项工作旨在评估 PMMA-NPLs 对模型两栖物种非洲爪蟾（Xenopus laevis）水生早期生命阶段的影响。为了实现这一目标，通过暴露胚胎[Nieuwkoop 和 Faber（NF）阶段 8-11]或蝌蚪（NF 45）于三种浓度的 PMMA-NPLs（1、100 和 1000μg/L）进行了两种类型的毒性试验：i）96 小时胚胎致畸试验，评估胚胎的存活率、畸形率和总体长（BL）；ii）48 小时摄食率试验，评估蝌蚪的存活率、摄食率（FR）、畸形率和生长率（体重-BW 和 BL）。PMMA-NPLs 暴露对非洲爪蟾胚胎的死亡率和畸形率没有显著影响，但在 1000μg PMMA-NPLs/L 时 BL 较低。在蝌蚪中，暴露于 PMMA-NPLs 后，存活率或 FR 没有观察到影响，但 BW 和 BL 发生了显著变化。此外，在暴露于 1000μg PMMA-NPLs/L 的 62.5%的蝌蚪中观察到腹部区域的解剖结构变化（肠道外溢）。尽管关于 NPLs 的环境水平的知识还很缺乏，但预计沉积物是这些污染物的汇，在那里它们可以被那些以食沉积物表面有机物为生的生物（如蝌蚪）利用。考虑到 PMMA 的持续释放和随后的积累，摄食试验中获得的畸形表明，在未来，这些纳米聚合物可能对两栖动物的水生生命阶段构成风险。
