The Halo Effect as a Public Good
The halo—or diffusion—effect of municipal water fluoridation programs refers to the dental health benefits that are enjoyed in communities, both adjacent and many miles removed, that may or may not have a fluoridated water supply. How does that work? Food and beverages produced with fluoridated water are shipped to and consumed in non-fluoridated areas. These foods and beverages contain fluoride at levels that are comparable to those in the original water source. So, fluoridation benefits not only the residents of the source community, but people in other places as well.
Studies have shown that the halo effect is stronger in states where most community water supplies are fluoridated. Although most large US cities fluoridate, many municipalities do not, and attempts to halt this common-sense practice persist. When they succeed, more people are denied this inexpensive public health intervention.
Opposition to fluoridation takes several forms. The anti-government sentiment and personal freedom movements that have gained traction in recent years are chief among them and played a critical role in the defeat of public referenda to fluoridate Wichita, Kansas in 2012 and Portland, Oregon in 2013.
While some opponents still question the decades of science supporting fluoridation, the public health, medical, and dental communities stand squarely behind the long-proven safety and effectiveness of US community water fluoridation. We also know that the practice of health promotion and disease prevention represents a public good that serves us best when it is not subject to opinion but held up to the scrutiny of the scientific process and best practices, the halo effect of which benefits us all.