Opponents say it has possible severe side effects. Supporters say that view is based on “junk science.”

Have you ever heard of a thing called fluoridation? Fluoridation of water? … Do you realize that fluoridation is the most monstrously conceived and dangerous communist plot we have ever had to face? — Gen. Jack D. Ripper in the 1964 Cold War era satire “Dr. Strangelove.”It’s easy today to scoff at the paranoid fringe that once feared that adding fluoride to American water supplies would turn us into commie zombies.

But 70 years after fluoridation began, fervent opposition continues.

In Kansas, Wichita voters rejected water fluoridation last fall for at least the third time since the 1960s and it wasn’t even close, sparking a call for statewide restrictions.

The fight against fluoridation is by no means confined to conservative states like Kansas. In Portland, Ore., protests arose from the left this fall when the city council voted to begin adding fluoride to that city’s water supply.

These days, opponents base their arguments on health concerns, saying they have the science to show that possible side effects of fluoridation could make people sick or stupid in the name of preventing tooth decay.

“I am very concerned,” said Mark Gietzen, a longtime anti-abortion crusader who heads the Kansas Republican Assembly, which calls itself the Republican wing of the Republican Party.

Four months ago, Gietzen had no opinion on fluoride. The topic put him to sleep. But he was awakened during the contentious campaign in Wichita.

Gietzen is now leading an effort to impose new statewide regulations that would include warning notices on water bills, as well as restrictions on the type of substances that can be added to tap water.

No bill has been introduced yet, but advocates of fluoridation say they are poised for a fight.

“The anti-fluoride folks are pretty passionate,” said Kevin Robertson, executive director of the Kansas Dental Association.

However, their arguments against water fluoridation are based on what Robertson calls “junk science,” and he vows that his group and others will work hard to convince lawmakers of that.

“We’re going to try to keep as much of Kansas fluoridated as possible,” he said.

According to the Centers for Disease Control, water fluoridation ranks as one of the 10 greatest public health achievements of the 20th century. It has led to a dramatic decrease in cavities among America’s youths.

Most people in the Kansas City area drink fluoridated water.

So do nearly two thirds of Kansans, according to the federal government. Compare that to 74 percent nationwide and upward of 80 percent in Missouri.

One reason the percentage isn’t higher in the Sunflower State is that Wichita, the largest city in Kansas, has never fluoridated its water.

Some naturally occurring fluoride is present in most drinking water. In Wichita, the rate is 0.3 parts per million, which is below what the federal government sees as the optimum level of 0.7 parts per million.

So a national foundation, the Pew Charitable Trusts, sought to change that. It helped form Wichitans for Healthy Teeth, a coalition of 500 dental health advocates that last year collected enough signatures to put a measure on the general election ballot that would have forced the local water utility to bring the fluoride level up to the recommended amount.

Proponents cited studies showing that tooth decay rates were 45 percent lower in communities with fluoridated water and that treating the water in Wichita would save residents $4.5 million a year in health and dental care costs.

But when the votes were tallied, the vote was 60 to 40 percent against, thanks to a well-organized and well-financed opposition.

Robertson attributed the result to doubts raised by fluoride opponents in ads paid for by the conservative Kansas Taxpayers Network.

“They dumped so much misinformation out,” he said. “The Internet is so full of stuff, and the people opposed to it threw out so much of it.”

Opponents said adding fluoride to water is like forcing people to take medication. Courts have rejected that claim, however, because fluoride is already in the water. Only the levels are different. Besides, there are other instances where food products are fortified. Iodine is added to salt. Vitamin D is added to milk.

But Gietzen said the research he has read raises troubling issues.

For example, he and other opponents say, fluoridation has links to cancer and arthritis.

Of particular concern, Gietzen said, is a Harvard School of Public Health study suggesting that high levels of fluoride stunted the IQs of children in China.

“The fluoride is collecting in your brain,” he said. “The animal studies have shown that.”

But the study’s authors acknowledged that their report — actually a study of other studies — showed slightly lower IQ levels in kids who drank water with fluoride levels 10 times what is found in U.S. water supplies.

Claims that fluoridation causes cancer and other health problems are specious too, proponents say, noting that the overwhelming majority of medical experts say adding fluoride at the proper level is safe and effective.

Another concern raised last fall by Wichitans Opposed to Fluoridation was that fluoride additives are different and more troublesome than the naturally occurring kind. Fluorosilicic acid, for instance, was said to be “an unpurified hazardous waste byproduct” from the manufacture of phosphate fertilizer and was never tested for safety.

Proponents countered that most of the fluoride used in water systems is from phosphate rock — which, only after the fluoride is extracted, is used to make fertilizer.

One thing both sides can agree on is that fluoridating water can alter the appearance of children’s teeth. In mild cases, it can cause barely noticeable white streaks. Heavier doses, which can come from swallowing fluoride toothpaste, can lead to brown stains.

Advocates on both sides also agree that the same arguments will be raised should the topic get any traction in Topeka.

Layered on top of that is the assertion by opponents that fluoridated water is superfluous in an age when you can go to the dentist and pay for fluoride treatment or get your fluoride from toothpaste and mouthwash.

But not everyone can afford regular dental care, and the poorest kids are the least likely to have an adult around to make sure they are brushing their teeth regularly and correctly, proponents say.

“In our county, we’ve got 17 percent of the people living below the poverty line,” said David Mehlhaff, spokesman for the Board of Public Utilities in Kansas City, Kan. “They don’t have access to dental plans. What about them?”

That issue of social justice helped drive a pro-fluoridation effort in liberal Portland.

But protests arose from the left this fall when the city council voted to begin adding fluoride to the water supply. Critics claimed that the science on the safety of fluoride was still unsettled and filed petitions that mandated a public vote on the switch in 2014.

In Kansas, Gietzen said he should have no trouble finding a lawmaker to sponsor a bill that would require water systems to inform customers of the presence of added fluoride in their water, along with possible health risks.

While the first part would not be anything new — all Kansas water systems are required to put out a water quality report each year listing what’s in the water — the warning would be.

A second and so far more nebulous provision would require that any additives put into the water supply “for the purpose of medicating the residents of that community” would have to pass unspecified purity standards.

The head of the group helping to promote the proposed legislation thinks, though, that it could take years to build enough support to make headway in the legislature.

It might be smarter to try for anti-fluoridation votes one community at a time, said Craig Gabel, president of Kansans for Liberty, a coalition of conservative groups like the tea party and the John Birch Society. The legislature already has a lot of things on its plate.

“There are many problems ahead of fluoride from the state’s point of view,” he said.

Still, Gietzen plans to make a go of it, he said, and will advise lawmakers to steer clear of Topeka’s fluoridated tap water while in session this year.

“The last thing Kansas needs is stupider representatives,” he said.