Background

There has been a rising interest within the scientific community and the public about the environmental risk related to the abundance of microplastics in aquatic environments. Up to now, however, scientific knowledge in this context has been scarce and insufficient for a reliable risk assessment. To remedy this scarcity of data, we investigated possible adverse effects of polystyrene particles (10⁴ particles/L) and the pesticide methiocarb (1 mg/L) in juvenile brown trout (Salmo trutta f. fario) both by themselves as well as in combination after a 96 h laboratory exposure. PS beads (density 1.05 g/mL) were cryogenically milled and fractionated resulting in irregular-shaped particles (< 50 µm). Besides body weight of the animals, biomarkers for proteotoxicity (stress protein family Hsp70), oxidative stress (superoxide dismutase, lipid peroxidation), and neurotoxicity (acetylcholinesterase, carboxylesterases) were analyzed. As an indicator of overall health, histopathological effects were studied in liver and gills of exposed fish.

Results

Polystyrene particles by themselves did not influence any of the investigated biomarkers. In contrast, the exposure to methiocarb led to a significant reduction of the activity of acetylcholinesterase and the two carboxylesterases. Moreover, the tissue integrity of liver and gills was impaired by the pesticide. Body weight, the oxidative stress and the stress protein levels were not influenced by methiocarb. Effects caused by co-exposure of polystyrene microplastics and methiocarb were the same as those caused by methiocarb alone.

Conclusions

Overall, methiocarb led to negative effects in juvenile brown trout. In contrast, polystyrene microplastics in the tested concentration did not affect the health of juvenile brown trout and did not modulate the toxicity of methiocarb in this fish species.

中文翻译：

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聚苯乙烯微塑料不会影响幼年褐鳟（Salmo trutta f。fario）或调节农药甲硫威的作用

背景

科学界和公众对与水生环境中大量微塑料相关的环境风险的兴趣日益浓厚。但是，到目前为止，在这种情况下的科学知识仍然匮乏，不足以进行可靠的风险评估。为了弥补这一数据的不足，我们调查了幼鳟鳟鱼（Salmo trutta f。fario）中聚苯乙烯颗粒（10 ⁴颗粒/ L）和杀虫剂甲硫威（1 mg / L）的可能的不利影响。），也可以在暴露96小时后单独使用或组合使用）。将PS珠（密度1.05 g / mL）进行低温研磨和分级，得到不规则形状的颗粒（<50 µm）。除了动物的体重以外，还分析了蛋白毒性（应激蛋白家族Hsp70），氧化应激（超氧化物歧化酶，脂质过氧化）和神经毒性（乙酰胆碱酯酶，羧酸酯酶）的生物标记。作为整体健康的指标，研究了肝脏和裸露liver鱼的组织病理学影响。

结果

聚苯乙烯颗粒本身不会影响任何已研究的生物标志物。相反，暴露于甲硫威导致乙酰胆碱酯酶和两种羧酸酯酶的活性显着降低。而且，该农药损害了肝脏和g的组织完整性。体重，氧化应激和应激蛋白水平不受甲硫威的影响。聚苯乙烯微塑料和甲硫威的共同暴露所造成的影响与仅由甲硫威的造成相同。

结论

总体而言，甲硫威对少年鳟鱼有负面影响。相比之下，测试浓度的聚苯乙烯微塑料不会影响幼体褐鳟的健康，也不会调节甲硫威对这种鱼类的毒性。