Insights into polystyrene microplastics on human health

Polystyrene microplastics (PS-MPs) are ubiquitous environmental contaminants characterized by high persistence and biological reactivity. Because PS-MPs can enter the human body through ingestion, inhalation, and potentially dermal contact, their toxicological effects have become an important public health concern. Although accumulating evidence supports the biological plausibility of PS-MP-induced toxicity, direct causal links to human diseases, particularly tumorigenesis, remain insufficiently established. This review focuses specifically on PS-MPs and summarizes current evidence regarding their effects on the gastrointestinal, nervous, reproductive, cardiovascular, pulmonary, renal, hepatic, immune, and integumentary systems, as well as their potential roles in inflammation and tumor-related biological processes. Additionally, we highlight the major mechanisms underlying PS-MP toxicity, including oxidative stress, barrier disruption, mitochondrial dysfunction, inflammatory signaling, apoptosis, pyroptosis, and cross-organ communication. Notably, we critically examine the translational limitations of current research, including the discrepancy between the high doses commonly used in experimental studies and real-world human exposure, differences among in vitro , animal, and human scenarios, inconsistencies in particle size and concentration, environmental aging, surface properties, and the limited understanding of absorption, distribution, metabolism, and excretion. This review provides a PS-MP-centered and critically structured framework for future toxicological assessment and human health risk evaluation.