Microplastic (MP) contamination represents a serious threat for marine organisms. Several lab studies demonstrated adverse effects induced by exposure to different MP polymers toward diverse marine species. However, the information regarding toxicity of polyethylene terephthalate (PET) MPs is largely unknown. The present study was aimed at investigating the adverse effects induced by 7-day exposure to two concentrations (0.125 or 12.5 µg/ml) micronized, irregular shaped and variable size PET microparticles (PET-MPs) toward Manila clam (Ruditapes philippinarum). Histological analyses were performed to assess tissue damage on digestive glands, gonads, gut and gills, whereas oxidative stress-related effects, including the concentration of pro-oxidant molecules, activity of antioxidant (superoxide dismutase – SOD, catalase – CAT and glutathione peroxidase – GPx) and detoxifying (glutathione S-transferase – GST) enzymes, as well as levels of lipid peroxidation, were determined in gills and digestive gland. Our results showed that clams ingest and egest micronized PET-MPs, but no marked histological alterations to bivalve tissues occurred. Although PET-MPs did not produce oxidative stress in the digestive gland, these materials significantly altered oxidative status of gills, leading to lipid peroxidation. No apparent clear indication of a weakness of bivalve health status was obtained in this study.

微塑料（MP）污染对海洋生物构成了严重威胁。几项实验室研究表明，将不同的MP聚合物暴露于各种海洋物种会引起不利影响。但是，关于聚对苯二甲酸乙二醇酯（PET）MP毒性的信息在很大程度上是未知的。本研究旨在调查7天暴露于两种浓度（0.125或12.5 µg / ml）的微粉化，不规则形状和尺寸可变的PET微粒（PET-MPs）对马尼拉蛤（Ruditapes philippinarum）引起的不良影响。。进行了组织学分析，以评估对消化腺，性腺，肠和g的组织损伤，而与氧化应激相关的影响，包括促氧化剂分子的浓度，抗氧化剂的活性（超氧化物歧化酶– SOD，过氧化氢酶– CAT和谷胱甘肽过氧化物酶–确定了g和消化腺中的GPx）和解毒（谷胱甘肽S-转移酶– GST）酶以及脂质过氧化的水平。我们的研究结果表明，蛤类会摄取并产生微粉化的PET-MP，但对双壳类动物组织没有明显的组织学改变。尽管PET-MP在消化腺中不产生氧化应激，但这些物质显着改变了g的氧化状态，从而导致脂质过氧化。在这项研究中，没有明显的迹象表明双壳类动物的健康状况较弱。