Microplastics (MPs) are regarded as a global issue due to their toxicity effects on fish and humans. Fish is a vital origin of human protein, which is necessary for body growth. Contamination of fish by MPs is a major hazard that requires special focus. After exposure to MPs alone or in combination with other pollutants, fish may experience a variety of health issues. MPs can cause tissue damage, oxidative stress, and changes in immune-related gene expression as well as antioxidant status in fish. After being exposed to MPs, fish suffer from neurotoxicity, growth retardation, and behavioral abnormalities. The consequences of MPs on human health are poorly understood. Due to the abundance of MPs in environment, exposure may occurviaconsumption, inhalation, and skin contact. Humans may experience oxidative stress, cytotoxicity, neurotoxicity, immune system disruption, and transfer of MPs to other tissues after being exposed to them. The toxic effects of MPs in both fish and human are still unknown. This detailed review has the potential to add to existing knowledge about the ecotoxicity effects of MPs in both fish and humans, which will be useful for the forthcoming study.

The present study was conducted to measure globally alarming of ten heavy metals (Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn and Mn) in surface water and sediment of the Old Brahmaputra River in Bangladesh. The observed order of heavy metal mean concentration in water and sediments is Al > Mn > Ni > Co > Cu > Pb > Zn > Cr > Cd > Hg in mg/l and Al > Mn > Zn > Ni > Pb > Cr > Cu > Co > Cd > Hg in mg/kg, respectively. The significant variations of Cr, Cu, Al and Ni were found in the water of all seasons (p < 0.05), while sediment showed Pb and Hg exhibited substantial changes in terms of seasons (p < 0.05). Principal component analysis and correlation matrix revealed that significant anthropogenic input of Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn and Mn in water and sediment. In case of water, very strong linear relationships exhibited in Ni versus Cu (0.911), Ni versus Al (0.910), Mn versus Co (0.882), Cr versus Al (0.877), Cu versus Cd (0.853), Ni versus Pb (0.850), Zn versus Cr (0.833), Ni versus Cd (0.828), Cu versus Cr (0.827), Al versus Cd (0.827) and Zn versus Co (0.804) at the significance level 0.05. In sediments, very strong linear relationships were noted in Zn versus Cr (0.889), Al versus Pb (0.848), Co versus Al (0.819) and Mn versus Co (0.806) at the significance level 0.05. The result discovered that water and sediment quality of the Old Brahmaputra River became contaminated due to the anthropogenic sources of industrial, domestic and irrigation discharges. This environmental monitoring and assessment research will be useful for the management and planning for the protection of this river.