Toxic effects of micro and nanoplastics on living system and recent advances in understanding their degradation routes

Plastic waste present in different forms in the environment has greatly impacted ecosystem in both terrestrial and marine ecosystems. From primary producers to tertiary consumers, all have shown the presence of micro- and nano-plastics within cells and tissues. Notably, in comparison to the environmental accumulation of plastic, its degradation occurs at a slow pace and is initially carried out by environmental factors such as pH, moisture, light, and temperature followed by the growth of microbial cells on their surfaces as biofouling. Many plastic-degrading microbes and biocatalysts have been identified which hold the potential to degrade plastic waste into useful end products. The thermal degradation of plastic waste via pyrolysis is eco-friendly process where high temperature and the absence of oxygen cause depolymerization of plastic into consequent monomer units. The improvement in the degradation rate of plastic waste using photocatalytic TiO 2 and ZnO has been significantly achieved and is promising to tackle the slow decomposition rate of plastic. This chapter will discuss recent advances in understanding thermal-photo and bio-degradation processes of different forms of plastic in different environments.