New evidence regarding the risks that microplastics (MP) ingestion pose to human and wildlife health are being revealed with progress made in ecotoxicological research. However, comprehensive and realistic approaches that evaluate multiple physiological responses simultaneously are still scarce despite their relevance to understand whole-organism effects. To address this information gap, we performed an experiment to assess the effects of MP on freshwater fish physiology from the molecular to the organismal level. Using a model species of global commercial importance () and MP type (recycling industry fragments), size (range between 125-1000 µm), and two concentrations of environmental relevance (0.75 and 8.25 µg/L). Experimental design included 5 blocks containing 3 treatment levels each one: control, low, and high MP concentration, with 6 fish each aquarium (5 blocks x 3 treatments x 6 fish per aquarium = 90 fish). Our results suggest that, under the experimental conditions applied, MP exposure did not cause adverse effects at the morphological (variation in size of gut), metabolic (variation of standard metabolic rate), or ecological (growth performance) levels. Nonetheless, we observed an increased frequency of micronucleated cells with increasing MP concentration (df = 42, t-value = 3.68, p-value < 0.001), showing the potential genotoxicity of MP, which can clearly harm fish health in long-term. Thus, despite being a highly resistant species, exposure to MP may generate negative effects in juvenile at cellular or subcellular levels. Our findings highlight that the manifestation of MP effects may vary over time, emphasizing the need for future studies to consider longer exposure durations in experimental designs.

中文翻译：

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揭示隐藏的威胁：微塑料对淡水鱼的基因毒性影响


随着生态毒理学研究的进展，有关微塑料 (MP) 摄入对人类和野生动物健康造成风险的新证据正在被揭示。然而，同时评估多种生理反应的全面而现实的方法仍然很少，尽管它们与理解整个生物体的影响相关。为了解决这一信息差距，我们进行了一项实验，从分子到有机体水平评估 MP 对淡水鱼生理学的影响。使用具有全球商业重要性的模型物种 () 和 MP 类型（回收行业碎片）、尺寸（范围在 125-1000 µm 之间）以及两个环境相关浓度（0.75 和 8.25 µg/L）。实验设计包括 5 个区块，每个区块包含 3 个处理级别：对照、低 MP 浓度和高 MP 浓度，每个水族箱有 6 条鱼（5 个区块 x 3 个处理 x 每个水族箱 6 条鱼 = 90 条鱼）。我们的结果表明，在所应用的实验条件下，MP暴露不会在形态（肠道大小的变化）、代谢（标准代谢率的变化）或生态（生长性能）水平上造成不利影响。尽管如此，我们观察到随着 MP 浓度的增加，微核细胞的频率也随之增加（df = 42，t 值 = 3.68，p 值 < 0.001），这表明 MP 具有潜在的遗传毒性，这显然会长期损害鱼类健康。因此，尽管是一种高度耐药的物种，接触 MP 可能会对幼鱼在细胞或亚细胞水平产生负面影响。我们的研究结果强调，MP 效应的表现可能会随着时间的推移而变化，强调未来的研究需要在实验设计中考虑更长的暴露时间。