Common tooth whitening products, which have been used by millions of people, are found to be safe and do not increase the risk of oral cancer when used as directed. This exhaustive review of the literature, including numerous unpublished clinical studies involving over 4,000 human subjects, appeared in an article by Dr. Ian Monroe entitled, " Use of Hydrogen Peroxide-Based Tooth Whitening Products and it Relationship to Oral Cancer," published in Journal of Esthetic and Restorative Dentistry.
Clinical and laboratory data on tooth whitening products show no evidence for the development of oral cancer or of other effects that could be associated with increased oral cancer risk. Exposures to hydrogen peroxide, generally the effective ingredient in tooth whiteners, are too low and of too short of a duration (30–60 minutes) to cause any oral tissue changes that could enhance risks for oral cancer development. Concentrations of hydrogen peroxide rapidly decline to near undetectable levels usually within 15 to 60 minutes.
Given the likely use of tooth whitening products by smokers, the review also sought to examine any possibility of increased oral cancer development due to combined exposure (i.e., hydrogen peroxide and carcinogenic agents that are present in cigarette smoke). A possible combined-effect, as seen in the increased likelihood of lung cancer development in smokers also exposed to asbestos, was found to be groundless with regards to bleaching and smoking and further illustrates the relative safety of tooth whitening products.