Inhalation risks of carbon fiber-reinforced plastic-derived emissions: Occupational exposure and regulatory...

Carbon fiber-reinforced plastics (CFRPs) are widely used in advanced applications, but emissions generated during manufacturing, machining, recycling, and end-of-life processing raise occupational and environmental inhalation concerns. This review synthesizes evidence on CFRP-derived particulate and gaseous emissions across the life cycle and identifies key uncertainties in inhalation risk assessment. Particular challenges include limited inhalation toxicity data, heterogeneous exposure scenarios and emitted materials, and insufficient real-world occupational exposure information. Respirable fiber-like fragments may be generated during mechanical processing, while thermal processes can produce ultrafine particles and hazardous gases. The available evidence has not demonstrated a magnitude or pattern of inhalation toxicity comparable to that established for asbestos and pathogenic high-aspect-ratio carbon nanotubes. However, the CFRP evidence base remains limited and heterogeneous, particularly for chronic exposure, and does not support a general quantitative comparison of relative toxicity. Future evaluation should integrate exposure characterization, material properties, internal dose, biopersistence, and toxicological evidence to reduce uncertainty and improve assessment of inhalation risks associated with CFRP-derived emissions.