Impacts of Microplastics on the Environment and Human Health: A Comprehensive Review of Sources, Distribution and Toxicological Effects

Abstract

Microplastics have become a global pollutant that threatens ecosystems and human health. This study aims to analyse the sources, distribution, ecotoxicological effects, and human health risks of microplastic exposure through a systematic review of recent literature (2017-2024). The research methods included collecting and analysing 45 scientific articles from indexed databases such as Scopus, Web of Science and PubMed using keywords related to microplastics, environmental pollution and health effects. The results showed that the main sources of microplastics are macroplastic degradation (35%), cosmetics (25%), synthetic textiles (20%) and tyre abrasion (15%). The distribution of microplastics has been detected in a variety of environments, including water (an average of 5,000 particles/m³ in the ocean), land (up to 1,000 particles/kg soil) and the atmosphere (50 particles/m³ in urban areas). At the ecotoxicological level, microplastics cause physiological disturbances in aquatic biota, such as a reduction in zooplankton growth rate (40%), liver damage in fish and accumulation in the food chain. In terrestrial environments, microplastics reduce soil fertility and inhibit plant growth by up to 30%. Risks to human health arise from consumption of contaminated food (0-10 particles/gram of seafood), drinking water (325 particles/l of bottled water) and inhalation. Microplastic particles (<10 μm) are capable of crossing the biological barrier and have been detected in blood (1.6 μg/mL), lung tissue and placenta. Mechanisms of toxicity include induction of oxidative stress (3-fold increase in ROS), inflammation (increase in IL-6 and TNF-α) and endocrine disruption (due to BPA and phthalates). Early epidemiological studies have linked microplastic exposure to an increased risk of obesity, reproductive disorders and genomic instability.