Opponents to water fluoridation in Duxbury say that the town is inadvertently adding lead to its water because that heavy metal is found in small concentrations in the town’s sodium fluoride additive.

Town officials say the levels of the lead in Duxbury’s water are well within the state and federal standards.

Duxbury Fluoride Choice, a residents’ group that wants to end the practice of adding fluoride to the town’s water supply, told the Board of Selectmen Monday that the brand of fluoride from China that Duxbury uses contains 0.5 percent of heavy metals including lead.

Susan Curtis of Duxbury Fluoride Choice told selectmen that she is troubled by the fact that in adding fluoride to the water the town is also adding lead because “lead is cumulative” in the body. She is also concerned that sodium fluoride Duxbury uses does not meet both of the National Science Foundation standards for drinking water additives that it should.

The fluoride packaging lists that it is 97 percent pure, said Curtis, but, she asked, “What is the other three percent?”

She believes that there is a lack of good inspection of this brand of sodium fluoride.

“When you have an industry that is self monitoring, what assurances do we have that it’s safe?” asked Curtis. “Fluoride has no place in our public water supply.”

Selectmen are in favor of ending water fluoridation and took a vote on the issue in January.

The board asked town counsel Anderson and Kreiger to review the issue fluoride and lead. Its attorneys found that the town is not doing anything wrong by adding fluoride to the water.

“The town is not in violation of any lead or other environmental standards in its fluoridation practice,” stated an email from Kevin Batt of Anderson and Kreiger.

“There is nothing for the BOS to be concerned about regarding the chemical Duxbury is using to fluoridate its water supply,” wrote Rebekah Lacey, an associate of Anderson and Kreiger. “The town is essentially allowed to add deminimis amounts of lead and other impurities in the process of adding a beneficial additive. It is required by the Safe Drinking Water Act to test its finished water, which ensures that any chemicals added during the treatment process don’t exceed EPA regulatory levels.”

“The EPA’s goal is zero lead in the water,” Curtis said.

Water Superintendent Peter Mackin said Duxbury’s drinking water is safe.

“It’s quite low,” he said of the level of lead in the water.

In testing 37 samples from Duxbury’s water supply in 2010, Mackin said 24 samples were lead free, 12 had between 0.002 and 0.003 levels of lead and one sample had 0.005.

The EPA level for lead in drinking water is 0.015 mg/L, according to Lacey.

Curtis said she was frustrated that it has taken so long for the board of health to meet regarding her group’s request to eliminate fluoride from town water. Curtis said in three months, Fluoride Choice has only had two meetings with the health board and that the board had to cancel meetings three times because it didn’t have a quorum.

“This is a political process but it shouldn’t be,” said Curtis. “It’s a health issue.”

The board of health solely has the power to end fluoridation at any time. It is meeting Thursday, March 7 at 7:15 p.m.to discuss fluoridation and the related issue of lead.