Seaweed as a sink for microplastic contamination: Uptake, identifications and food safety implications

Microplastics (MPs) are a rising global concern, infiltrating marine ecosystems and food sources, including seaweed, which is widely consumed. This review examines the prevalence of MPs in seaweed, their role as pathways for MPs to enter marine food webs, and the potential risks to marine organisms and human health. Findings indicate that it contributes up to 45.5 % of total dietary microplastic (MP) intake through seaweed, with particularly high levels in South Asian regions, which is concerning. Factors such as seaweeds morphology, surface properties, epibionts, and environmental conditions influence MP uptake. Microplastic contamination in seaweed leads to bioaccumulation and biomagnification, affecting marine organisms through oxidative stress, growth disruption, immune issues, and metabolic disturbances. Seaweeds bioaccumulate heavy metals from seawater, and microplastics (MPs) attract these metals, increasing toxicity might enter food chain posing health risk. Simple methods like water washing can reduce MPs on seaweed surfaces. However, in this case, innovative detection methods and advanced removal technologies are still underexplored. Similarly, Microplastic (MP) contamination presents economic risks to the global seaweed industry, valued at USD 7.0 billion in 2023, with exports reaching 819,100 tonnes worth USD 3.21 billion. By 2024, the industry, dominated by Asian countries, had grown to USD 22.13 billion, but MP contamination threatens further expansion by undermining consumer confidence, reducing market value, and increasing regulatory scrutiny. Asia accounts for 47.9 % of global seafood MP contamination, the economic repercussions could be substantial. Future research should explore the long-term effects of environmental aging on microplastic debris in seaweeds related marine organisms, emphasizing food security and human health. Studies should also focus on the toxicological effects of micro- and Nano plastics (MNPs) from seaweed-based contaminants in human food consumption. Robust government initiatives and policies promoting a circular economy are crucial for effective management.