Microplastics: A Narrative Review on Modes of Exposure and Impact on Human Health

BackgroundPlastics have been widely used for several decades, but their persistence in the environment has resulted in the widespread presence of microplastics (MPs) in the air, water, and soil. With particle sizes smaller than 5 mm, MPs are now recognized as emerging contaminants of concern owing to their potential impact on human health.ObjectiveThis study aimed to conduct a critical narrative umbrella review of published reviews and primary studies on microplastic exposure and human health. Specifically, the objective was to synthesize evidence across the major exposure pathways (ingestion, inhalation, and dermal), summarize the associated health outcomes, and critically appraise common themes, inconsistencies, and knowledge gaps. This review provides guidance for future research and policy directions by aligning findings with methodological strengths and limitations.ResultsMPs are consistently detected in food, water, air, human stool, blood, placenta, and breast milk. Reported outcomes include gastrointestinal inflammation, gut microbiota disruption, respiratory diseases, endocrine and reproductive dysfunction, and possible neurotoxicity. Inhalation is increasingly recognized as significant, and ingestion remains the most studied, whereas dermal exposure is underexplored.ConclusionMicroplastics represent a pervasive and complex public health challenge. This umbrella review underscores the need for harmonized methodologies, epidemiological investigations, and mechanistic studies that reflect real-world exposure. Strengthening this evidence base is essential for risk assessment, regulation, and public awareness of the health impacts of microplastics.