Cetylpyridinium chloride (CPC) (IMAGE) Hokkaido University Caption Cetylpyridinium chloride (CPC), the chemical tested in the study (Photo: Ryo Takeda) Credit Ryo Takeda Usage Restrictions This image is copyrighted but may be used to report this study if credited as instructed. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.