Variations in the spatial distribution of expanded polystyrene marine debris: Are Asian's coastlines more affected?

Expanded polystyrene (EPS), commonly known as Styrofoam, is a foam plastic material regularly found in the marine environment. The objective of this study is to investigate the frequency of EPS among all plastic waste on beaches and in marine surface waters in order to evaluate its spatial variability. On average, 23.0% and 17.2% of plastics on beaches and in marine surface waters are composed of EPS, respectively. In Asia, 40.4% and 31.0% of plastic on beaches and in marine surface waters are EPS, significantly higher than the rest of the world where EPS only accounts for 17.3% and 6.5% on beaches and in water. Higher EPS proportions are observed in Asia for both macro- and microplastics. Among the seven sub-regions identified outside of Asia, the Mediterranean and Black Sea sub-region has the highest EPS proportion in beach while the Indian Ocean sub-region has the highest EPS proportion in water. A comparison between macro- and microplastic from selected studies suggests that the rate of fragmentation may be higher on beaches than in marine waters. We have highlighted fishery activity, tropical cyclones, and open dumping as major factors contributing to the high proportion of EPS in the Asian region. Finally, we evaluated EPS bans in different parts of the world and concluded that while bans may be effective in reducing EPS input into the marine environment, other factors should be considered when implementing these policies.