Human and environmental safety of carbon nanotubes across their life cycle

Carbon nanotubes are a large family of carbon-based hollow cylindrical structures with unique physicochemical properties that have motivated research for diverse applications; some have reached commercialization. Recent actions in the European Union that propose to ban this entire class of materials highlight an unmet need to precisely define carbon nanotubes, to better understand their toxicological risk effects on human health and the environment throughout their life cycle, and to communicate science-based policy-driving information comprising their taxonomy, safe sourcing, processing, production, manufacturing, handling, use, transportation, and disposal. In this review, we discuss current information and knowledge gaps regarding these issues. We highlight the significance of life cycle assessments of carbon nanotubes and provide a framework to inform policy decisions.