Micro-Nano Plastics and 6-PPD-Q in Cardio-Pulmonary Health: Environmental Sources, Systemic Exposure, and Mechanistic Insights.

Micro- and nanoplastics (MNPs) and the tire-derived transformation product 6-PPD-Quinone (6-PPD-Q) have emerged as pervasive environmental pollutants with critical implications for cardiopulmonary health and ecosystem integrity. This review identifies tire wear particles (TWPs) as a primary source of both airborne and waterborne MNPs, as well as 6-PPD, which readily oxidizes into the highly toxic 6-PPD-Q. These contaminants have been detected across diverse environmental compartments including air, soil, water, and remote ecosystems highlighting their global distribution and persistence. Human exposure occurs primarily through inhalation, ingestion, and dermal contact. Although mechanistic studies remain limited, available evidence indicates that MNPs and 6-PPD-Q induce oxidative stress, inflammation, mitochondrial dysfunction, apoptosis, and endothelial damage, particularly in pulmonary and cardiovascular tissues. Their detection in human tissues and excreta raises urgent public health concerns. Beyond human health, these toxicants adversely affect soil microbial communities, aquatic organisms, and crop productivity, underscoring their broader ecological footprint within a One Health framework. Regulatory oversight remains limited, especially for nanoplastics and tire-derived compounds, emphasizing the need for standardized detection methods and globally coordinated research and policy initiatives. This review underscores the urgency of implementing comprehensive mitigation strategies, including environmental monitoring, occupational safeguards, and public education, to address the growing threat posed by TWPs, MNPs, and 6-PPD-Q.