COSTA MESA — Councilman Gary Monahan wants the city to adopt a resolution opposing the use of mercury in dental clinics.

Monahan brought the largely symbolic item forward after a request was made by Californians for Green Dentistry, a group of dentists and residents against the use of mercury in dental clinics.

The group plans to make a presentation during Tuesday's City Council meeting, when the resolution is scheduled for consideration, according to a city staff report.

Amalgam dental filling should be eliminated because studies show that dental clinics are major sources of the mercury found in fish and water, the group says.

The silver-colored fillings are made of 40% to 50% mercury; 25% silver; and 25% to 35% copper, zinc and tin mixture, according to information provided to the city by the dentistry group.

Dentists can practice green dentistry by using a dental amalgam separator or by using composite, the white resin fillings.

"We have an autistic child, and we believe it's a major cause of autism," Monahan said of his 15-year-old son, Ethan. "There are so many alternatives and I can't understand why we're putting this in our mouth. It's just very dangerous for anybody to have these fillings."

The Centers for Disease Control in Atlanta earlier this year announced that there is no proven link between vaccines containing mercury and autism-spectrum disorders. A report by a British physician linking autism and mercury has been discredited.

Eliminating amalgam from dental clinics might not be that easy, said Dr. Ronald Housepian, who practices dentistry in Costa Mesa.

He said the silver-colored fillings are less expensive than composite fillings. Some insurance companies don't offer them, and those who don't want silver fillings get stuck with paying the prices, he said.

The composites are also much more demanding and require what's called clean dry fields, areas in the mouths that are not bleeding, Housepian said.

"For children who are moving or can't keep it dry, it may not even last," he said.

If adopted by the council, the resolution will not have any legal weight, and the city cannot use it to force dental clinics to stop using mercury, Monahan said.

But the resolution can provide the city's stance on the issue for possible future actions by the state or the federal government.

"I'm looking for council's support, as the leaders of the city, to make a statement that dental amalgam contains up to 50% of mercury, and it's incredibly dangerous to people getting them and to the environment," Monahan said.