Studies: Some say salmon in jeopardy

There’s little scientific debate that fluoride, at the proper dose, can reduce tooth decay.

But research into fluoride’s impact on fish and wildlife is more skimpy and less conclusive.

That makes it hard for environmentally minded voters to separate political rhetoric from reality during Portland’s emotionally charged referendum campaign over water fluoridation.

Kimberly Kaminski, chairwoman of Clean Water Portland, says it’s misleading to even call fluoridation good for children’s health.

“Our children are already exposed to many chemicals,” Kaminski says. “We already have so many chemicals in our water, in our soil, that this is just adding to our toxic burden.”

An allied group, Oregon Citizens for Safe Drinking Water, goes further on its website: “The problems associated with fluoride pollution are significant in Oregon and the entire Columbia River basin. Excess fluoride in Northwest water negatively impacts salmon and other aquatic species. Fluoride does not break down and therefore accumulates in the environment.”

Fluoridation supporters are equally strident.

It’s misleading to even call fluoride a chemical, because it’s a naturally occurring mineral, says Mel Rader, co-executive director of Upstream Public Health. He likens fluoridation to adding iodine to salt or Vitamin D to milk.

“There’s no impact on salmon,” Rader says. “Scientists who’ve looked at this issue know that.”

The Everyone Deserves Healthy Teeth Coalition makes a stronger assertion in a campaign piece: “No credible studies have shown any adverse effects on any living organism at the optimal fluoride level, including salmon.”

For voters who want to make their own judgments, here’s a look at some of the scientific research:

Salmon at risk?

• 2006 report by the National Academy of Sciences, “Fluoride in Drinking Water: A Scientific Review of EPA’s Standards,” (

A panel of independent scientists, reviewing research from the prior decade, raised concerns about three human health hazards from excess fluoride: severe dental fluorosis for children under the age of 8, the risk of bone fractures and several forms of skeletal fluorosis after lifetime exposure. In response, the U.S. Department of Health and Human Services lowered the recommended dose of fluoride in drinking water to 0.7 milligrams per liter; down from a range of 0.7 milligrams to 1.2 milligrams. And the Environmental Protection Agency announced it would consider lowering the maximum amount of fluoride it permits in public waterways, currently 4 milligrams per liter.

• 2012 study published in Environmental Health Perspectives, “Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis,” led by Harvard School of Public Health researchers (

Reviewing other studies, they concluded that children in areas with naturally high levels of fluoride have “significantly lower” IQs. “The results support the possibility of an adverse effect of high fluoride exposure on children’s neurodevelopment.”

• 1989 study published in North American Journal of Fisheries Management; “Evidence for Fluoride Effects on Salmon Passage at John Day Dam, Columbia River, 1982—1986” )

National Marine Fisheries Service biologists David Dankaer and Douglas Dey found that fluoride emitted by an aluminum plant near the John Day Dam negatively affected the survival rate and passage time of salmon navigating the dam passage. They concluded that a safe level of fluoride in rivers for chinook and coho salmon is no more than 0.2 milligrams per liter.

• 1994 study published in Fluoride, “The Impact of Artificial Fluoridation on Salmon Species in the Northwest USA and British Columbia, Canada” (

Researchers found fluoridated water enters rivers at levels higher than 0.2 milligrams per liter. They cited a study that found effluent from the fluoridated water system of Minneapolis-St. Paul entered the Mississippi River at 1.21 milligrams per liter, and took 16 kilometers before the water was back down to the safe levels of 0.2 milligrams per liter.

Dueling scientists

Fluoride supporters note that the Harvard IQ study largely focused on Chinese communities with fluoride levels several times higher than those ordinarily found in the U.S.

Rader says the Damkaer and Day study, which proposed the salmon-safe fluoride level of 0.2 milligrams per liter, has “significant flaws.” He cites a critical analysis in 2006 by Troutdale consultant Richard Shepard, “Drinking Water Fluoridation and Salmon” (, but that wasn’t published in a scientific journal, so it carries less weight.

Steve Kucas reviewed published studies on salmon and fluoride for the Portland Water Bureau, where he works as environmental compliance program manager. “The literature pretty much supports a concentration of 0.2 milligrams per liter, or 2 parts per million, as being a sensitive level for fish,” Kucas says.

The fluoride concentration in Portland’s water supply would be more than three times greater than that. However, Rader notes, a smaller level winds up in the Columbia River.

On dry-weather days, 63 million gallons of sewage, most of it from Portland’s water supply, arrives at the city’s Columbia Boulevard Wastewater Treatment Plant, says operations manager Mike Ciolli. During wet weather, or about one-third of the year, that jumps to 80 million to 400 million gallons a day, meaning rainfall would dilute the fluoride.

Some of the fluoride likely would bind to solids in the treatment process, ultimately getting shipped to Eastern Oregon for fertilizer, Ciolli says.

A 1964 study of multiple California municipalities found 57 percent of the fluoride was removed during sewage treatment. That study was cited in an environmental review by Washington’s Tacoma-Pierce County Health Department in 2002 (

Portland’s treated wastewater is piped into the Columbia River at West Hayden Island. The Oregon Department of Environmental Quality permits a mixing zone there, where emissions limits on chlorine may be temporarily exceeded.

The river flow there is one million cubic feet per second, Ciolli says, “so the dilution is immediate.”

The Tacoma environmental review projected fluoride at levels below 0.2 milligrams per liter once treated sewage leaves mixing zones in area rivers.

• A 2004 paper by Howard Pollick, published in International Journal of Occupational and Environmental Health, found that fluoride concentration in rivers downstream from municipal treatment plants increases by less than 0.01 milligram per liter. Citing literature reviews by Tacoma-Pierce County Health Department and Port Angeles, Wash., he concluded: “No negative impact of water fluoridation on the environment has been established.”

His paper was entitled “Water Fluoridation and the Environment: Current Perspective in the United States,” (

Pollick, a dentistry professor at University of California at San Francisco, is an advocate of fluoridation.