Portland, Oregon, the largest U.S. city without fluoridation chemicals added to its drinking water, rejected water fluoridation Tuesday in an election watched around the country.

Despite being outspent by more than a 3 to 1 margin, fluoridation opponents defeated the measure with the current vote count at 60.5 to 39.4%. The latest polling showed especially strong opposition from Portland’s Latinos and African Americans. A majority of Democrats, Republicans and Independents also opposed the measure.  The diverse and bipartisan coalition opposing the fluoridation measure ranged from the Sierra Club’s Columbia Group and the Portland NAACP to a group of over 200 Portland medical professionals and the conservative Cascade Policy Institute. The vote came just weeks after data from a state study showed Oregon’s child cavity rates had dropped over 19% in recent years without any increased fluoridation and that cavity rates in unfluoridated Portland were actually lower than rates in Oregon’s fluoridated cities.

The loss for fluoridation promoters follows the November vote rejecting fluoridation in Wichita, Kansas, the second largest unfluoridated U.S. city. Both votes come after recent studies by the National Academy of Sciences (NAS), Harvard scientists and other top researchers linking even low levels of fluoride in drinking water with human health risks ranging from decreased thyroid function and depressed childhood IQ to elevated bone cancer risks in boys. Other recent studies have tied fluoridation chemicals to health risks related to arsenic, a common contaminant found in the fluoridation chemical fluorosilicic acid, and lead, which fluoridation chemicals have shown to leach from plumbing.

Relying on the NAS report findings that infants and children were getting too much fluoride, the U.S. Dept. of Health and Human Services called for a 40% reduction in maximum fluoridation levels in 2011. The Centers for Disease Control and the American Dental Association, while still claiming fluoridation is safe for infants, also issued warnings that regular use of fluoridated water to mix infant formula put infants at risk of excessive fluoride intake and damage to teeth known as “fluorosis.” (Visit the Media Page at cleanwaterportland.org for an overview of recent scientific studies related to fluoridation risks relevant to the Portland campaign and related media coverage.)

Fluoridation promoters attempt to dismiss the recent studies and rely on the intentional campaign tactic of framing fluoridation opponents as being “anti-science.” A number of prominent scientists, however, including two members of the National Academy of Sciences Committee that published the over 500-page “Fluoride in Drinking Water” report, say the science about fluoridation risks has changed, and that the public has clearly noticed.

Scientist Dr. Kathleen Thiessen, PhD, who served on the National Academy of Sciences Committee on Fluoride stated, “The scientific evidence available today highlights a number of reasons to be concerned about the continued practice of water fluoridation. When people become aware of the actual risks, it is not surprising they decide against fluoridation.”

“All current research shows that a lifetime of fluoridation might save one filling. It’s not clinically relevant and certainly not cost effective,” says Dr. Hardy Limeback, DDS who was also a member of National Academy of Sciences Committee on Fluoride and previously was the head of Preventive Dentistry at the University of Toronto. Limeback also addressed the risks of fluoridation, explaining that they included “impaired brain and endocrine function as well as an increased risk for certain cancers, that have convinced me we should never have allowed fluoridation to continue as long as it has.”

“This vote reflects that people are becoming more aware that there are real risks to adding fluoridation chemicals to our drinking water, and just because its something many cities have done for decades doesn’t mean its a good idea,” adds Dr. William Hirzy, PhD, the former vice president of the U.S. EPA Headquarters Union of Scientists. Hirzy teaches at American University and recently published a study on the risks of arsenic contained in the fluoridation chemical fluorosilicic acid.

Those involved in the Portland campaign agree. “It was amazing to see people who had been pro-fluoride switch their positions when they saw there were very real and credible scientific reasons to be concerned, and that claims of unquestionable fluoridation safety was more myth than fact,” says Portland physical therapist and mother of two Kellie Barnes, who gave over 30 presentations on the recent fluoridation science to groups around Portland as a volunteer with Clean Water Portland, the group that lead the fluoridation opposition.

“We are very pleased to see the fluoridation measure defeated so we can start to focus on solutions that do not involve the risks of fluoridation chemicals and that actually work, such as increasing access to dental care,” says Clifford Walker who is a board member of the Portland NAACP.

Portland dentist Dr. Jay Levy, DDS, who was active in opposing the Portland fluoridation measure, agreed. “Many dentists I know have the best intentions when it comes to fluoridation, but they just are not aware that the science regarding fluoridation risks has changed so significantly in recent years. For many, the belief that fluoridation is safe is akin to a knee-jerk reflex based on what they learned in dental school, and that’s a real problem when you’re dealing with public health.”

“Across the country, we are seeing people who once supported fluoridation switch their position after spending some time reading the recent studies for themselves and realizing that a practice they long assumed to be safe is far riskier than they thought,” says Michael Connett, a researcher with the Fluoride Action Network, the nation’s leading organization on fluoridation issues.

“Portland voters chose to protect children from risky fluoridation chemicals. As a community, we stand on the side of science, which clearly shows growing cause for concern about health risks associated with fluorosilicic acid. Anyone can spend an hour on the internet and read for themselves what the National Academy of Science report has to say about fluoride’s risks,” says Antonia Giedwoyn with the Sierra Club’s Columbia Group, which has opposed the Portland fluoridation measure.