Beyond the shoreline: Uncovering the cost and life cycle impacts of marine expanded polystyrene debris

Managing marine pollution from expanded polystyrene (EPS) is a critical environmental challenge, yet reliable empirical data on the actual recovery burden are often lacking. This investigation addresses this gap by using primary field data from three comprehensive sampling cycles. Through a combined life cycle assessment and cost analysis, the environmental and economic impacts of remediation versus industrial prevention were compared. The results quantify the cost of inaction, showing that collection from hard-to-reach shores accounts for 99.5% of the total cost and 83% of CO₂ emissions, with geographic dispersion and labour intensity as the main limiting factors. In contrast, mechanical processing is technologically mature and has low operating costs. The investigation also redefines sustainability metrics based on the waste's end use, valorizing recycled EPS as a substitute for natural mineral aggregates (sand). This approach turns the disadvantage of low density into an advantage, achieving a greater than 99% reduction in carbon footprint per cubic metre compared to mineral aggregates. The present article clearly highlights that collecting waste before entering the marine environment is essential. At the same time, converting marine EPS into a resource is viable, as the environmental benefits of preserving natural deposits offset the high recovery costs, supporting a practical circular economy strategy.