Cell Biology and Genetics unit, Department of Zoology, University of Ibadan, Nigeria; Leibniz Research Centre for Working Environment and Human Factors (IfADo), Technical University of Dortmund, 44139 Dortmund, Germany.
Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina Viale Ferdinando Stagno d'Alcontres 31 98166, S Agata, Messina, Italy.
Environ Toxicol Pharmacol. 2019 May;68:61-74. doi: 10.1016/j.etap.2019.03.001. Epub 2019 Mar 8.
The global plastics production has increased from 1.5 million tons in the 1950s to 335 million tons in 2016, with plastics discharged into virtually all components of the environment. Plastics rarely biodegrade but through different processes they fragment into microplastics and nanoplastics, which have been reported as ubiquitous pollutants in all marine environments worldwide. This study is a review of trend in marine plastic pollution with focus on the current toxicological consequences. Microplastics are capable of absorbing organic contaminants, metals and pathogens from the environment into organisms. This exacerbates its toxicological profile as they interact to induced greater toxic effects. Early studies focused on the accumulation of plastics in the marine environment, entanglement of and ingestions by marine vertebrates, with seabirds used as bioindicators. Entanglement in plastic debris increases asphyxiation through drowning, restrict feeding but increases starvation, skin abrasions and skeletal injuries. Plastic ingestion causes blockage of the guts which may cause injury of the gut lining, morbidity and mortality. Small sizes of the microplastics enhance their translocation across the gastro-intestinal membranes via endocytosis-like mechanisms and distribution into tissues and organs. While in biological systems, microplastics increase dysregulation of gene expression required for the control of oxidative stress and activating the expression of nuclear factor E2-related factor (Nrf) signaling pathway in marine vertebrates and invertebrates. These alterations are responsible for microplastics induction of oxidative stress, immunological responses, genomic instability, disruption of endocrine system, neurotoxicity, reproductive abnormities, embryotoxicity and trans-generational toxicity. It is possible that the toxicological effects of microplastics will continue beyond 2020 the timeline for its ending by world environmental groups. Considering that most countries in African and Asia (major contributors of global plastic pollutions) are yet to come to terms with the enormity of microplastic pollution. Hence, majority of countries from these regions are yet to reduce, re-use or re-circle plastic materials to enhance its abatement.
全球塑料产量从 20 世纪 50 年代的 150 万吨增加到 2016 年的 3350 万吨，塑料几乎排放到环境的所有组成部分。塑料很少生物降解，但通过不同的过程，它们会碎裂成微塑料和纳米塑料，这些塑料已被报道为全球所有海洋环境中无处不在的污染物。本研究综述了海洋塑料污染的趋势，重点是当前的毒理学后果。微塑料能够从环境中吸收有机污染物、金属和病原体进入生物体。由于它们相互作用会引起更大的毒性效应，因此加剧了其毒性特征。早期的研究集中在塑料在海洋环境中的积累、海洋脊椎动物的缠绕和摄入，以及海鸟作为生物标志物。由于塑料碎片的缠绕，通过溺水导致窒息、限制摄食但增加饥饿、皮肤擦伤和骨骼损伤的风险增加。塑料摄入会导致肠道堵塞，可能导致肠道内层损伤、发病率和死亡率增加。微塑料的小尺寸通过内吞作用样机制增强其穿过胃肠膜的易位，并分布到组织和器官中。虽然在生物系统中，微塑料增加了对控制氧化应激所需的基因表达的失调，并激活了海洋脊椎动物和无脊椎动物中核因子 E2 相关因子（Nrf）信号通路的表达。这些改变是微塑料诱导氧化应激、免疫反应、基因组不稳定性、内分泌系统紊乱、神经毒性、生殖异常、胚胎毒性和跨代毒性的原因。微塑料的毒理学效应可能会持续到 2020 年之后，届时世界环保组织将结束塑料生产。考虑到非洲和亚洲（全球塑料污染的主要贡献者）的大多数国家尚未认识到微塑料污染的严重性。因此，这些地区的大多数国家尚未减少、再利用或再循环塑料材料以加强其减排。
