‘Silver’ Dental Material Will Carry Warning : Health: To conform to state law, a manufacturer agrees to alert dentists and patients about exposure to mercury, a substance linked to birth defects and miscarriages. Risk is low, officials say.

SACRAMENTO — A major manufacturer of the “silver” commonly used in dental fillings has agreed to issue warnings to California dentists and patients that the product exposes them to mercury, a substance that may cause birth defects and miscarriages.

The action, announced Tuesday, was part of the settlement of a lawsuit brought against manufacturers by the Environmental Law Foundation under California’s Proposition 65, the 1986 anti-toxics initiative.

The company, Jeneric/Pentron Inc. of Connecticut, agreed to provide warning labels on packaging and a sign for display in dentists’ offices. Similar signs are now required under Proposition 65 for a number of products containing substances that can cause cancer, birth defects, miscarriages or infertility.

The settlement cannot force dentists to place the warnings, which feature a distinctive yellow triangle, in their waiting rooms. However, the company has agreed to stop selling the product to dentists who do not comply--once similar settlements have been reached with manufacturers covering 75% of the mercury amalgam market.

James Wheaton, president of the Oakland-based environmental group, hailed the settlement--the first by a major manufacturer of dental amalgam--as an important step in eliminating unnecessary exposure to mercury, long known to be toxic in high doses.

“Warning dental patients is not just a good idea, it’s the law,” he said. But he added that there is no reason for panic, even for adults with a mouthful of silver.

“For most adults these levels don’t pose an acute hazard,” Wheaton said. “They shouldn’t go out and plan to remove all their fillings.”

The aim instead is to encourage dental patients, particularly women in their child-bearing years, to discuss the use of alternative, mercury-free materials such as gold and ceramics with their dentists.

The settlement was quickly attacked Tuesday on legal and medical grounds.

The American Dental Assn. and its California affiliate insist that patients have no cause for concern, saying there are no good scientific studies connecting mercury in fillings to miscarriages or birth defects.

The dental groups point out that mercury has been used in dental fillings, which also contain silver, copper and tin, for more than 150 years.

“This is absolutely preposterous,” said Dr. Terry Donovan, an associate professor at the USC School of Dentistry and chairman of the American Dental Assn.’s council on dental materials, instruments and equipment.

“There’s not a single shred of evidence in any peer-reviewed scientific journal that shows that mercury from silver amalgam fillings has any detrimental effect on health, including that of unborn children,” Donovan said.

He pointed to a U.S. Public Health Service review released in January that concluded that there “is no solid evidence of any harm for millions of Americans who have these fillings” and “no persuasive reason to believe that avoiding amalgams or having them removed will have a beneficial effect on health.” The only exceptions are a small group of individuals with mercury allergies.

Scientists on both sides of the controversy generally agree that the highest exposures--and the greatest potential dangers--are to the dentists, hygienists and dental assistants who work with the material over a long period of time.

“If anybody is at risk, it’s the dentist,” Donovan said. “We’re around amalgam every day, putting it in people’s teeth, taking it out and mixing it.”

William Pease, a research toxicologist at the UC Berkeley School of Public Health, pointed to studies showing that mercury vapors do cause birth defects and miscarriages in animals. And one study of dental workers showed a higher miscarriage rate among women who mixed amalgams compared to those who did not.

“There’s on-the-table evidence of reproductive effects on dental hygienists,” Pease said.

Whether the low daily dose of mercury from fillings represents a hazard to patients or their unborn children is less certain, Pease said. But a World Health Organization study pointed to dental fillings as the principal source of mercury exposure in industrialized countries, except for people who eat unusually large amounts of fish.

There is no dispute that high levels of mercury can cause both miscarriages and damage to the fetus. Since 1990, the chemical has been listed on the state’s official Proposition 65 list as a substance known to have reproductive effects.

Under that measure, manufacturers and others must warn the public about exposures to listed substances at levels as low as one-thousandth of the amount known to cause harm. And by that measure, Pease said, “no levels of mercury are acceptable.”

Rather than risk a lawsuit and a potential penalty of $328,000, Jeneric/Pentron agreed to distribute the warnings and to reimburse the Environmental Law Foundation $26,400 for its legal expenses.

The sign intended for patients features a distinctive yellow triangle and states: “WARNING. This office uses amalgam filling materials which contain and expose you to mercury, a chemical known to the state of California to cause birth defects and other reproductive harm. Please consult your dentist for more information.”

Twenty manufacturers and distributors have banded together to file a lawsuit in federal court in San Diego, contending that the state of California has no authority to impose warning requirements on products regulated by the federal government.

Stan Landfair, a Los Angeles attorney representing the manufacturers and distributors, contended that the Environmental Law Foundation suit is misdirected. He said his clients cannot force dentists to display warnings. The purpose of the suit, he said, was simply “to scare off the public . . . to turn dentists to more expensive filling materials. To gold or ceramic, which are so expensive . . . that most dental insurers presently won’t even pay for them.”