Microplastic Pollution and Its Emerging Health Implications: A Comprehensive Review of Human Exposure Pathways and Toxicological Risks

Abstract

Abstract

Microplastic pollution is increasingly recognized as a critical global environmental and public health issue due to its widespread distribution, persistent nature, and potential for bioaccumulation and toxicity. Microplastics, defined as plastic particles smaller than 5 mm, originate from both primary sources—such as microbeads in cosmetics, synthetic textiles, and industrial abrasives—and secondary sources, resulting from the fragmentation of larger plastic debris through photochemical, mechanical, and biological processes. These particles have been detected in various environmental matrices including marine and freshwater systems, soils, the atmosphere, and even in remote regions like the Arctic and Antarctic. Human exposure to microplastics occurs primarily through ingestion of contaminated food and water, inhalation of airborne fibers and dust, and, to a lesser extent, dermal contact. Once inside the body, microplastics can translocate across epithelial barriers and accumulate in organs such as the lungs, liver, kidneys, and placenta. Toxicological studies reveal that microplastics can trigger oxidative stress, inflammation, immune disruption, endocrine interference, and DNA damage. Moreover, due to their large surface area and hydrophobic properties, microplastics act as vectors for hazardous contaminants such as heavy metals, persistent organic pollutants (POPs), and per- and polyfluoroalkyl substances (PFAS), further compounding their toxicological risks. Despite growing research interest, significant knowledge gaps remain regarding the mechanisms of toxicity, the cumulative effects of long-term exposure, and the lack of standardized detection methods in human tissues. This paper provides a comprehensive review of the sources, distribution, exposure pathways, and toxicological risks of microplastics, while identifying critical research gaps and recommending policy interventions, public awareness strategies, and sustainable alternatives to plastics. A multidisciplinary and globally coordinated approach is urgently needed to mitigate the health and ecological impacts of microplastics.