Microplastic pollution in Costa Rican marine ecosystems: Origins, ecotoxicological impacts, and mitigation strategies

Microplastics (MPs) and nanoplastics (NPs) have become ubiquitous worldwide, posing complex challenges for marine organisms, ecosystems, and human health. In Costa Rica alone, approximately 4000 tons of solid waste are generated daily, of which about 11 % is plastic. Nearly 600 million single-use plastic bottles are produced yearly, with ∼90 % not being collected. Consequently, reports of MPs in beaches, crustaceans, fishes, and bivalves are increasing on the Pacific and Caribbean coasts. Evidence suggests these plastic fragments can induce oxidative stress and inflammation in organisms, affect fundamental physiological processes (e.g., feeding, reproduction), and may even cross the blood–brain barrier. Recent policies in Costa Rica, including Law N°9786 (single-use plastics) and a proposed ban on MPs in cosmetics (Bill No. 23,694), mark progress. However, enforcement challenges remain—particularly given the country’s limited wastewater treatment coverage. This review discusses key sources of MPs (e.g., wastewater, synthetic fibers, tire wear), current sampling and characterization protocols, and ecotoxicological consequences for marine life and humans. We further analyze existing legislation, highlighting gaps and prospective solutions, and propose an integrated approach involving technological upgrades, biodegradable polymers, and microbial degradation strategies to mitigate plastic pollution. • Costa Rica produces up to 600 million single-use plastic bottles annually, with ∼90 % uncollected. • Microplastics have been identified in marine species on the Pacific and Caribbean coasts. • Ecotoxicological impacts include oxidative stress, membrane damage, and potential trophic transfer up to humans. • Recent regulations (Law N°9786, Bill No. 23694) aim to curb plastic use but face enforcement challenges. • Technological, legislative, and educational approaches must be integrated to mitigate MPs/NPs.