A Review for Prioritizing Microplastic Regulation and Research: An Integral Approach

Microplastics (MPs) are a growing threat to aquatic ecosystems, yet research and regulations often treat all plastics as one homogenous group. This overlooks critical distinctions, leading to regulatory gaps and inconsistent research that hinders risk assessment and environmental modeling. This review proposes a prioritized list of plastic and MP types based on available data. Factors like usage, waste generation, existing regulations, toxicity (including additives and monomers), ease of identification, and degradation mechanisms are considered. We identified polyester, polyamide, acrylic fibers (PES/PA/PAN), polyethylene (PE), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polystyrene (PS) as top priorities. The extensive use and short lifespans of single-use PP, PE, and PET products lead to significant waste generation. Except for PE, all prioritized polymers have potentially toxic additives or monomers. PET and PVC pose isolation and identification challenges, while PVC, PET, and PA readily fragment into MPs. Among MP forms, fibers are a top concern due to high production volumes, potential for containing toxic additives, and difficulty in identification. Spherical MPs, primarily originating from direct production, warrant focus for regulatory efforts. Based on the analysis of the available data, we propose recommendations to develop stronger and more relevant regulations and key research opportunity areas to advance our understanding of MPs in the environment. By prioritizing specific plastic types and MP forms, we can achieve greater efficiency in addressing the growing problem of plastic pollution.