It's an issue that has been the center of controversy for decades.  Dentists credit adding fluoride to our drinking water supply for a decrease in tooth decay, but a growing number of critics say it's time to stop.

Brian Nylaan, DDS, runs a practice in Kent County.  "It's got a 55 year proven track record," Dr. Nylaan says of fluoride.

Others say it's a chemical that can be dangerous to your health. "It's like putting a medicinal property in water and we don't do that, we don't put medicines in water," says Barb Meconis of Holistic Care Approach in Grand Rapids Township.  She steers clear of city water; she uses a water purifier at her clinic.  "People should drink purified water, and that means water that's gone through some type of filtration system so that both the fluoride and the chlorine has been filtered out of the water."

In the past several years, studies have found people who are exposed to higher amounts of fluoride have lower IQ's than their counterparts. Dr. Tammy Born says she sees patients suffering from flourosis - too much fluoride.  She says her concerns are osteoporosis and worse.  "There's possibly some evidence that it could affect cancer and some symptoms, and I think the downsides now outweigh the upsides,"  Dr. Tammy Born told FOX 17 News.

The CDC previously said the safe level of fluoride for city water is between .7 parts per million, to 1.2 parts per million.  This year, the CDC announced it would consider a recommendation to drop the maximum level of fluoride in city water to .7 ppm; the very low end of the current scale.

Last year, concerned citizens in Mount Pleasant worked with leaders to halt adding fluoride to the water supply there.  "We used to work in buildings with asbestos, it was very dangerous for the workers who worked there, and so now we've taken it out,"  Dr. Born said.  "We used to sell mercury thermometers; if they broke it was very dangerous.  We should re-evaluate."

Grand Rapids is the fluoride pioneer: the first city in the world to add it to the water supply.  There's even a huge, blue steel sculpture downtown honoring our fluoride history.  "If there's new science that suggests we reduce fluoride, we'll be the first to take a look at that," Mayor George Heartwell said.  "But I've not seen the science that's convincing to me at this point."

While the CDC considers lowering the maximum recommendation, Dr. Nylaan worries about potential setbacks in dental health.  "See if there's trends, if the trends come where the teens and the 20-somethings and 30-somethings start getting more decay," Dr. Nylaan says.  "If that happens, I hope they have guts enough to change it back."

The CDC will issue a final report later this spring.  

Click HERE for the CDC Report on Fluoride.

Click HERE for the American Dental Association's website.

Click HERE for the Fluoride Action Network.

Click HERE to see how much Fluoride is in your water.