AUGUSTA – Critics of the use of mercury-containing dental amalgam celebrated Maine’s effort to heighten patient awareness of its potential health effects.

Stepping up a campaign targeting a substance commonly used to fill cavities, anti-mercury activists joined Gov. Angus King and Senate President Michael Michaud on Thursday for a re-enactment of the signing of informed consent legislation passed earlier this year.

Under the new law, dentists will be required to distribute informational brochures to patients requiring fillings. Brochures will be developed by the state Bureau of Health and provided to dentists at cost.

The brochures will describe available alternatives to mercury amalgam and detail potential advantages and disadvantages. Other information will address the durability, cost and aesthetic quality of mercury amalgam and alternative materials.

Mercury is a highly toxic, naturally occurring element. It can be released into the environment from numerous sources, including the burning of fossil fuels.

There is strong evidence linking mercury exposure to neurological problems, as well as immune system and cardiological problems, according to a report issued by the National Academy of Sciences in Washington last year.

The average amalgam filling, which is 50 percent mercury, contains more than half a gram of mercury, according to the Maine Toxics Action Coalition.

Amalgam fillings, which also contain silver, copper and tin, can be cheaper than other types, including plastic and porcelain, and can last longer.

King said Thursday that despite “some controversy” over the health effects of amalgam fillings, he considered the new Maine law “national leadership legislation” that could give dental patients “at least the ability to make an intelligent decision.”

Michaud, D-East Millinocket, credited advocates of the legislation for bucking elements of the medical establishment.

The American Dental Association has said there is no sound scientific evidence supporting a link between amalgam fillings and systemic diseases or chronic illness.

Executive Director Frances Miliano of the Maine Dental Association said Thursday the state group believes “all the reliable science does point to the safety of amalgam.”

The bill that finally was passed by the Legislature originally called for a ban on mercury fillings for young children and women of childbearing age.

The informed consent measure that won enactment put Maine with California and Arizona among states requiring some disclosure, according to the Maine Toxics Action Coalition.

Dental fillings constitute the largest source of direct mercury pollution in wastewater, according to a recent report by a coalition of New England environmental groups.