Microplastics Exposure and Redox Imbalance in Human Tissues: Mechanisms, Biomarkers, and Health Implications

Abstract

Microplastics-plastic particles smaller than 5 mm, have emerged as pervasive environmental contaminants detected in air, water, food, and consumer products. Human exposure occurs through ingestion, inhalation, and dermal contact, leading to measurable microplastic particles and plastic-associated chemicals in blood, lung tissue, placenta, and stool. Growing experimental and epidemiological evidence suggests that microplastics may disrupt redox homeostasis, triggering oxidative stress and downstream inflammatory and metabolic alterations. Redox imbalance arises when reactive oxygen species (ROS) generation exceeds antioxidant defense capacity, damaging lipids, proteins, and DNA. Microplastics can induce oxidative stress through particle surface reactivity, leaching of additives such as phthalates and bisphenols, adsorption of environmental pollutants, and activation of immune pathways. This review synthesizes current knowledge on human exposure pathways, cellular and molecular mechanisms linking microplastics to redox dysregulation, tissue-specific effects, biomarkers of oxidative injury, and potential long-term health consequences. It also highlights methodological challenges in exposure assessment and proposes research priorities to clarify dose–response relationships and vulnerable populations. Understanding how microplastics contribute to redox imbalance in human tissues is critical for risk assessment, regulatory action, and the development of preventive strategies. Keywords: microplastics, oxidative stress, redox imbalance, reactive oxygen species, environmental toxicology.