Microplastics in the Marine Environment: Sources, Distribution, Transport, Ecological and Human Health Impacts and Mitigation Strategies

Microplastics have emerged as a persistent and prevalent threat to human health and the marine environment due to their widespread use and poor management, including low recycling rates, inadequate waste management, improper disposal, and inadequate control of plastic leakage into the environment. Plastic pollution is transported to the marine ecosystem through both ocean-based and land-based pathways and can be fragmented into microplastics (<5 mm) and nanoplastics (<1 µm). The study explains the sources, distribution, mechanisms of degradation, and transport pathways to the marine environment. Land-based activities are recognized as the dominant source, causing approximately 70–80% of marine plastic pollution. Domestic greywater is highlighted as a significant and common source of microplastics due to the release of microbeads and synthetic fibers from different sources, such as laundry, washbasins, and personal care products (PCPs). Similarly, greywater release from maritime vessels and cruise ships significantly contributes to marine microplastic pollution. The study discusses the biotic and abiotic degradation mechanisms. The health and environmental effects of microplastics are measured across different trophic levels. Ingestion and bioaccumulation of microplastics can cause physiological and reproductive disturbances. Human exposure through seafood consumption and inhalation may result in skin infections, cardiovascular complications, gastrointestinal disorders, and respiratory problems. The mitigation and control measures include improvements in wastewater treatment, public awareness, policy regulations, and biodegradable alternatives to support sustainable protection of the marine environment.