Micro/nanoplastics and human health: A review of the evidence, consequences, and toxicity assessment

Micro/nanoplastics are one of the emerging contaminants having potential to affect human health negatively owing to their inherent properties as well as presence of various chemicals/additives into it. A number of studies have demonstrated the presence of these ubiquitous contaminants in various organs and biological fluids of human body. Physiological systems have also been found to be affected by the invasion of these particles. Notably, altered cell morphology and mitochondrial cell transport, reduction in cell viability, oxidative stress, conformational changes and denaturation of proteins have commonly been observed. Nevertheless, further investigations are required to substantiate these findings. The morphological features and chemical characteristics of these particles also play a significant role in determining the level of invasion and impacts produced. Size, shape, molecular weight/polymer chain length, crystallinity, and colour cause significant changes in the impacts posed onto human body. Hence, this review summarizes the evidence of micro/nanoplastics' presence in human body along with showcasing the probable impacts on physiological system. The influence of micro/nanoplastics' physical and chemical characteristics on human health impacts is also discussed in detail followed by a framework on toxicity assessment.