Fragmented or otherwise miniaturized plastic materials in the form of micro- or nanoplastics have been of nagging environmental concern. Perturbation of organismal physiology and behavior by micro- and nanoplastics have been widely documented for marine invertebrates. Some of these effects are also manifested by larger marine vertebrates such as fishes. More recently, possible effects of micro- and nanoplastics on mammalian gut microbiota as well as host cellular and metabolic toxicity have been reported in mouse models. Human exposure to micro- and nanoplastics occurs largely through ingestion, as these are found in food or derived from food packaging, but also in a less well-defined manner though inhalation. The pathophysiological consequences of acute and chronic micro- and nanoplastics exposure in the mammalian system, particularly humans, are yet unclear. In this review, we focus on the recent findings related to the potential toxicity and detrimental effects of micro- and nanoplastics as demonstrated in mouse models as well as human cell lines. The prevailing data suggest that micro- and nanoplastics accumulation in mammalian and human tissues would likely have negative, yet unclear long-term consequences. There is a need for cellular and systemic toxicity due to micro- and nanoplastics to be better illuminated, and the underlying mechanisms defined by further work.
The ongoing Coronavirus Disease 2019 (COVID-19) global pandemic has triggered a flurry of associated research publications, numbering to ~137 papers a day since February 2020. This rate of publication appears to be exceptionally high, when compared to research papers published on other similar topics. Searches of COVID-19-associated publications on PubMed and Retraction Watch Database indicate that the retraction record appearance rate for COVID-19-related research is also exceptionally high compared to other related research topics in viral epidemics/pandemics and surpasses the basal level of about 4 in 10,000 papers. This finding serves as a reminder and caution against any lapses in the standard of work, peer review, and publication of COVID-19-related research.