A meta-analytic review of microplastic pollution in the Indian Ocean: Ecological health and seafood safety risk implications

The Indian Ocean (IO) currently bears the second largest plastic load and therefore, has a high potential for microplastic (MP) pollution. Despite the findings from individual studies, the overall MP pollution in the IO is still unclear. Therefore, this meta-analytic review aimed to identify the overall MP contamination state, its ecological health and seafood safety risk implications, and identify future priority areas for MP research in the IO. The data for the occurrence of MPs in seawater, sediment and marine biota in the IO were analysed. Concentrations of MPs in surface water and sediment were in a wide range (surface water: 0.01 to 372,000.00 particles per m3; sediment: 36.80 to 10,600.00 items per kg, respectively) while lower range (0.016 to 10.65 particles per individual) was observed in biota. The meta-analysis indicated that PE was the most abundant polymer type in all three matrices and PE prevalence was higher in sediment. Fibres were the most prevalent MP shape of all three matrices in the IO. The Higher MP accumulation was identified in shrimps (p < 0.05) than the fish species. Results further confirmed that MPs do not magnify along the food chain (p > 0.05). Ecological risk and hazardous effects increased with the presence of polyvinyl chloride (PVC), polyurethane (PUR) and PA due to their high hazardous scores. Overall results indicated that IO is in the high-risk category due to the elevated levels of MP pollution with reference to all three matrices.