Micro- and nanoplastics and the kidney: exposure pathways, toxicokinetics, and pathophysiological insights

Micro- and nanoplastics (MNPs) are increasingly recognized as pervasive environmental contaminants with major implications for human health. Their ubiquity across air, water, food chains and indoor environments, together with the release of plastic-associated chemicals—including bisphenols, phthalates, PFAS and heavy metals—creates a complex and continuous exposure scenario. MNPs can enter the human body through ingestion, inhalation, dermal contact and medical devices; nanoplastics, in particular, may cross biological barriers, reach the systemic circulation and accumulate in target organs such as the kidney.Experimental evidence identifies multiple mechanisms of nephrotoxicity. MNPs induce oxidative stress, mitochondrial dysfunction, ferroptosis, epithelial barrier disruption, inflammatory activation and tubulo-interstitial fibrosis. Adsorbed contaminants further amplify these effects through endocrine disruption, immunotoxicity and metabolic dysregulation. The detection of MNPs in human kidney tissue and urine supports their systemic bioavailability and renal handling. This review synthesizes current knowledge on environmental and clinical exposure sources, routes of absorption, toxicokinetics and pathogenic pathways of MNP-induced renal injury. Understanding these processes is essential to correctly interpret clinical observations and to recognize MNPs asemerging environmental determinants of kidney health.