Microplastics in the marine environment: Challenges and the shift towards sustainable plastics and plasticizers.

The United Nations (UN) estimate that around 75-199 million tons of plastic is floating in the world's oceans today. Continuous unintentional disposal of plastic waste in marine environments has and continues to cause significant biological impacts to various marine organisms ranging from mild difficulties in swimming or superficial damage to critical organ malfunctions and mortality. Over time, plastics in these environments degrade into microplastics which are now acknowledged as a pervasive harmful pollutant found in the cryosphere, atmosphere and hydrosphere. In response to this issue, the production of bespoke biodegradable bioplastics derived from renewable resources, such as vegetable oils, starch and plant fibres, is emerging to mitigate our reliance on environmentally persistent conventional fossil fuel-based plastics. While bioplastics degrade more readily than conventional plastics, they present new challenges, including leaching of toxic chemical additives and plasticizers into the environment. Consequently, various techniques have been explored in the search for sustainable plasticizers, from cheap, non-toxic compounds, such as vegetable oils and sugars to hyperbranched structures with limited migration. This article seeks to explain the intricate relationship between the problem of microplastics in marine environments and the strategies that have been investigated to address it thus far.