Fluoridation was a controversial topic 50 years ago and it’s a controversial topic today.

In Yarmouth, the question of whether or not to add fluoride to the town’s water supply drew nearly 40 people to a recent public hearing of the board of health, which has been charged by Yarmouth selectmen to explore the issue. A quick show of hands at the afternoon meeting indicated that opponents outnumbered proponents 5 to 1.

“Town water tastes wonderful. Why put something into it?” asked West Yarmouth’s Linda Greene, who said she didn’t think it was appropriate to “medicate the whole town” for the sake of one segment of the population, namely the children whose teeth would benefit from fluoridated water. Greene was one of several speakers at the June 20 hearing at the Yarmouth Senior Center who said children now had other means of obtaining fluoride, either from local dentists or voluntary school programs.

Residents raised a number of concerns about fluoridation, from senior health issues to groundwater to the inconvenience of having to buy bottled water. John Newton of West Yarmouth made no bones about his opposition and said that, should the town fluoridate its water, he would solicit residents for a class-action lawsuit.

“I am unalterably opposed to putting this poison in our water,” said Newton.

Speaking in favor of fluoridation was Dr. Peter Laband, a retired dentist who said that the arguments against fluoridation heard in 2005 were similar to the ones he heard as a young dentist decades ago.

“It was an emotional issue in 1950 and 1951 and it still is,” said Laband, who said that research has consistently shown a connection between fluoridated water and fewer cavities in children. Laband added that making sure children comply with individual fluoride applications was hit-or-miss, just like similar appeals to brush and floss regularly.

“The kids do have cavities and plenty of them,” said Laband, whose suggestion to fluoridate was met with a small smattering of applause.

Although the tone of the hearing was serious, it was not without its humor. At one point Laband indicated that major cities like Boston and Springfield were fluoridating their water with no catastrophic effects.

“There are no bodies in the streets to my knowledge,” said Laband.

Laband’s quip was immediately countered by Elizabeth Space of Yarmouth Port, who wanted to know why seniors needed to drink fluoridated water intended to help prevent childhood cavities.

“There are plenty of people here who put their teeth in a jar at night,” said Space.

Yarmouth Health Director Bruce Murphy said the board’s immediate goal was not a decision but a full hearing of how residents feel about the issue.

“This is still part of an ongoing process,” said Murphy. “It’s an emotional issue but there were some great comments on both sides.”

That comment period will continue at the board’s next fluoridation hearing at 7 p.m. Monday, July 18 at the senior center. That hearing, which Murphy said was scheduled at night to accommodate residents who could not make afternoon meetings, will be attended by Mary Foley, director of the Office of Oral Health for the Massachusetts Department of Public Health. That hearing will also include a question-and-answer period.

Otis Air National Guard Base in Bourne is the only area on Cape Cod using fluoridated water; 135 Massachusetts communities receive water fluoridation.

According to its Web site, the U.S. Centers for Disease Control and Prevention lists the fluoridation of drinking water as one of this country’s “top 10 great public health achievements” of the 20th century.

But debate over the process is still fierce: many nations in Western Europe do not fluoridate their drinking water and opponents claim that fluoridated water can increase the risks of thyroid and kidney problems as well as osteosarcoma, a rare form of bone cancer.