As a consequence of the global ubiquity of plastic pollution, scientists, decision-makers, and the public often ask whether macroplastics (>5 mm) and microplastics (<5 mm) have a realized ecological threat. In 2016, we conducted a systematic review of the literature and made a call for further research testing hypotheses about ecological effects. In the subsequent years, the amount of relevant research has risen tremendously. Here, we reassess the literature to determine the current weight of evidence about the effects of plastic pollution across all levels of biological organization. Our data spans marine, freshwater, and terrestrial environments. We extracted data from 139 lab and field studies testing 577 independent effects across a variety of taxa and with various types, sizes, and shapes of plastic. Overall, 59% of the tested effects were detected. Of these, 58% were due to microplastics and 42% were due to macroplastics. Of the effects that were not detected, 94% were from microplastics and 6% were from macroplastics. We found evidence that whether or not an effect is detected, as well as the severity and direction of the effect, is driven by dose, particle shape, polymer type, and particle size. Based on our analyses, there is no doubt that macroplastics are causing ecological effects, however, the effects of microplastics are much more complex. We also assessed the environmental relevancy of experimental studies by comparing the doses used in each exposure to the concentrations and sizes of microplastics found in the environment. We determined that only 17% of the concentrations used in experimental studies have been found in nature, and that 80% of particle sizes used in experiments fall below the size range of the majority of environmental sampling. Based on our systematic review and meta-analysis, we make a call for future work that recognizes the complexity of microplastics and designs tests to better understand how different types, sizes, shapes, doses, and exposure durations affect wildlife. We also call for more ecologically and environmentally relevant studies, particularly in freshwater and terrestrial environments.

中文翻译：

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关于塑料污染影响的已知和未知：荟萃分析和系统综述。

由于塑料污染在全球范围内普遍存在，科学家，决策者和公众经常询问大塑料（> 5毫米）和微塑料（<5毫米）是否对生态构成了威胁。2016年，我们对文献进行了系统回顾，并呼吁进行进一步研究，以检验有关生态影响的假设。在随后的几年中，相关研究的数量急剧增加。在这里，我们重新评估文献，以确定有关塑料污染在整个生物组织各个层面上的影响的当前证据权重。我们的数据涵盖了海洋，淡水和陆地环境。我们从139个实验室和现场研究中提取了数据，测试了577种在各种分类单元上以及各种类型，尺寸和形状的塑料的独立效应。总体，检测到59％的测试效果。其中，58％是由微塑料引起的，42％是由大塑料引起的。在未发现的影响中，有94％来自微塑料，而6％来自大塑料。我们发现有证据表明，是否检测到效果以及效果的严重程度和方向受剂量，颗粒形状，聚合物类型和粒径的影响。根据我们的分析，毫无疑问，大塑料正在引起生态效应，但是，微塑料的作用要复杂得多。我们还通过比较每次暴露中使用的剂量与环境中发现的微塑料的浓度和大小来评估实验研究与环境的相关性。我们确定自然界中仅发现了用于实验研究的浓度的17％，并且实验中使用的80％的粒径低于大多数环境采样的粒径范围。基于我们的系统评价和荟萃分析，我们呼吁未来的工作认识到微塑料的复杂性，并设计测试以更好地了解不同类型，大小，形状，剂量和暴露时间对野生生物的影响。我们还呼吁开展更多与生态和环境相关的研究，尤其是在淡水和陆地环境中。