"These results indicate that MWCNT can increase the risk of cancer in mice exposed to a known carcinogen. The study did not indicate that MWCNTs alone cause cancer in mice. This research is an important step in our understanding of the hazards associated with MWCNT, but before we can determine whether MWCNT pose an occupational cancer risk, we need more information about workplace exposures, the types and nature of MWCNT being used in the workplace, and how that compares to the material used in this study. Research is underway at NIOSH to learn more about worker exposures and the potential occupational health risks associated with exposure to MWCNT and other types of CNTs and CNFs. As results from ongoing research become available, NIOSH will reassess its recommendations for CNT and CNF and make appropriate revisions as needed. NIOSH urges employers to share this information with workers and customers. NIOSH also requests that professional and trade associations and labor organizations inform their members about the potential hazards of CNT and CNF."