Fluoride was recently designated as a high-priority chemical for further scientific review into its potential health impacts by California, and for possible listing under Proposition 65.  

What is Proposition 65?

In California, Proposition 65 requires public warnings for listed chemicals, which include carcinogens and reproductive toxins. The process of considering potentially carcinogenic chemicals for listing under Proposition 65 includes review by California’s Carcinogen Identification Committee (CIC). The CIC serves in an advisory capacity to the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA).  

How and when will this decision be made?

OEHHA is considering fluoride for listing under Proposition 65. On May 29, 2009, the CIC studied fluoride among 38 candidate chemicals. The committee recommended that fluoride be included in the high-priority group for further scientific review by OEHHA, along with eight other chemicals. In reaching its decision, the CIC assessed the number of scientific studies that have been conducted concerning fluoride, the types of studies done—such as epidemiological and animal studies— and the potential for human exposure to fluoride. The CIC attributed its decision partly to widespread concern regarding fluoride, as shown by the approximately 30 studies, conducted over the past three decades, that the CIC took into account in its determination.  

OEHHA staff must next decide the order in which it will further review fluoride and the other eight highpriority chemicals. That further review will involve detailed examination of the previously identified studies and additional studies from OEHHA and the public. The OEHHA will compile the information in these studies into a detailed document for further review by the CIC. The CIC will assess that information in a meeting in 2010 or later, at which time public comments will also be considered. The CIC may then decide that fluoride should be listed under Proposition 65.

Why is fluoride—long thought a safe additive to ensure healthy teeth— now being considered as potentially “toxic”?

Environmental groups encouraged OEHHA to review fluoride because epidemiological studies have suggested a connection between the ingestion of tap water containing fluoride and increased incidence of osteosarcoma, a type of bone cancer, in teenage boys. Dental and consumer-products industry groups present a contrary position, asserting that the scientific evidence does not support further review of fluoride. For example, a report by the National Resource Council found evidence of fluoride’s cancer-causing potential to be “tentative and mixed,” especially with regard to bone cancer.

Because of fluoride’s broad use in drinking water, toothpaste and other consumer products, debate will continue as the OEHHA process progresses.