National

Dental group defends mercury fillings amid mounting evidence of risks

In this demonstration photo of a mannequin, experts used a trick discovered by chemists to show how much mercury can be released when a mercury filling is drilled out of a tooth without protective measures. Only the mercury atoms can absorb photons beamed toward the mannequin at a specific wavelength.
In this demonstration photo of a mannequin, experts used a trick discovered by chemists to show how much mercury can be released when a mercury filling is drilled out of a tooth without protective measures. Only the mercury atoms can absorb photons beamed toward the mannequin at a specific wavelength. Courtesy of Randall Moore

For decades, the American Dental Association has resolutely defended the safety of mercury fillings in the teeth of more than 100 million Americans, even muzzling dentists who dared to warn patients that such fillings might make them sick.

The association has lobbied the Food and Drug Administration to ensure the fillings, which contain one of the world’s most menacing toxins, receive a government seal of safety and wouldn’t be tightly regulated.

For years, the ADA also resisted Environmental Protection Agency rules that would force dentists to stop dumping tons of mercury debris down public sewer lines, even as the United States and 128 other nations negotiated a treaty to curb mercury’s global spread.

But now, evidence is emerging of the potential consequences of the U.S. dental industry’s longtime reliance on mercury and its chief advocacy group’s determined crusade to fend off any and all challenges.

In the 1800s, the American Society of Dental Surgeons declared it to be malpractice to place mercury fillings in a patient’s teeth, but the group ultimately gave way to the American Dental Association, which has vouched for the treatments’ safety

New scientific research has found that the fillings may indeed harm millions of people, especially men and boys. Further, the lax controls over dental clinic discharges have allowed the chemical to spread into rivers and streams, into the air through sludge incineration and even onto cropland as fertilizer.

The new research, by a team based at the University of Washington, concluded that low-level releases of mercury from fillings present long-term risks of brain damage for people with certain genetic variants. The findings are based on data underpinning one of the same two pivotal clinical studies of American and Portuguese children that the dental association has cited as proof the compounds are safe.

In 2006, after results of the initial studies were published, several of the researchers decided to re-evaluate data from 330 Portuguese students to identify those with subtle genetic impairments and see if they were more vulnerable to mercury inhalation in annual tests of their memory, concentration and other neurological activities. Kids with mercury fillings performed significantly worse on the tests than those who got mercury-free treatments.

The results, in four papers published in scientific journals from 2011 to 2014, have escaped public attention, although the authors say up to 40 percent of the population has at least one of the genetic traits and could be affected.

Diana Echeverria, a scientist who collaborated with University of Washington toxicologist James Woods and others in the reassessment, said the susceptible groups face “a lifetime risk” of neurological damage.

“We’re not talking about a small risk,” said Echeverria, who works for the Seattle-based Battelle Centers for Public Health Research and Evaluation.

Twenty-five percent to 50 percent of people have these (genetic variants). There were these deficits that were accounted for by having them. . . . We reasoned that we would see these if we would simply genotype these children. That is indeed what we saw.

Former University of Washington toxicologist James Woods

The Food and Drug Administration has staunchly defended the safety of the mercury-laden dental products, known in the trade as amalgams. But the University of Washington’s findings prompted a European Union scientific panel to urge dentists to explore alternatives, such as popular tooth-colored plastic resins.

Behind the scenes, FDA officials also have shown deepening concern about mercury fillings, especially since two scientific advisory panels, in 2006 and 2010, criticized the agency’s analysis of science on the issue and its failure to protect vulnerable groups.

In July, McClatchy reported that the FDA drafted a safety communication that urged dentists to avoid using mercury fillings, where possible, and advised them not to use them in susceptible groups, including pregnant women and small children.

But officials of the Department of Health and Human Services blocked the warning on grounds that the cost of pricier alternatives might lead low-income patients to let decayed teeth go untreated, an argument often sounded by the American Dental Association.

The 157,000-member dental association and its state and local chapters have long been potent — and successful — advocates for dentists. Again and again, they have prevailed in impeding or weakening efforts to control mercury in dentistry.

Over the years, the ADA has:

— Argued against FDA safety warnings about mercury fillings for pregnant women and small children.

— Imposed a gag rule barring member dentists, including those specializing in the safe removal of mercury fillings, from telling patients the compounds could harm their health.

— Lobbied to ensure that the international treaty signed by 129 countries would call for a phase-down of mercury uses worldwide, not a phase-out that eventually would ban dentists’ use of mercury fillings.

— Cut a deal in the final days of George W. Bush’s presidency that put off the issuance of regulations requiring dentists to install mercury “separators,” so they can properly dispose of their mercury debris, in favor of a voluntary approach.

They (the dental association leaders) are powerful, and they are very scared of good science, because if it comes out on the wrong side of their goal of using amalgam, then they have to rethink and retool their practice. . . . These people should be more open-minded and more scientifically driven — evidence-based, rather than protecting their turf.

Diana Echeverria, researcher into mercury’s effects

The dental association declined to make any senior officials available for an interview, but its president, Maxine Feinberg, recently wrote McClatchy: “No properly designed, peer-reviewed scientific study links dental amalgam to any neurological or systemic disease, and that’s the scientifically sound bottom line.”

In written responses to questions, the association said it supported the international treaty, the Minamata Convention, which ultimately set no deadlines for nations to meet its goals and gave them great leeway in how to do so.

The association also said it generally supports the EPA’s proposed rule to require safe disposal of mercury waste but hopes the agency will accept its “simple suggestions” for easing burdens on its members, such as by relaxing from 99 percent to 95 percent requirements for the separators’ efficiency to reduce the devices’ estimated average $1,300 one-time cost — plus a few hundred dollars each year to operate them.

The dental industry’s long-held position that mercury fillings are the safest, most durable solution for restoring decayed teeth, however, appears to have produced a troubling legacy.

Not only have America’s dentists placed compounds that continuously release toxins into the mouths of an estimated 181 million people, but they also have washed hundreds of tons of mercury-tainted debris into public sewer lines — and ultimately the environment — over the last several decades.

Washington attorney James Turner, who has represented consumers in a 23-year campaign to ban mercury fillings, believes the dental association’s advocacy on these issues has been motivated at least in part by an unspoken economic interest: to “avoid enormously costly product liability suits” by patients sickened from mercury exposure.

The ADA owes no legal duty of care to protect the public from allegedly dangerous products used by dentists. The ADA did not manufacture, design, supply or install the mercury-containing amalgams. . . . Dissemination of information related to the practice of dentistry does not create a duty of care to protect the public from potential injury.

American Dental Association response to a patient lawsuit

For decades, the dental association contended the alloys, comprising about 50 percent elemental mercury and a blend of metals that usually includes tin, copper and silver, were inert once placed in teeth.

However, the discussion took a turn in the 1980s when new instrumentation showed microscopic amounts of mercury coming off the compounds’ surfaces, especially during chewing.

The World Health Organization says inhaling or ingesting mercury, “even in small amounts . . . may cause serious health problems,” including depression, tremors, memory loss, cognitive and motor dysfunction, as well as damage to the lungs, kidneys and digestive and immune systems.

Sue Casteel, Kansas regional representative for the Agency for Toxic Substances and Disease Registry, compares the risk of an acute, one-time mercury exposure and chronic long-term exposure from mercury leaching from dental fillings.

That hasn’t dissuaded the dental association, which has continued to challenge any implication that mercury fillings might cause harm.

The association’s Model Code of Ethics bars members from even suggesting to a patient that mercury fillings can be injurious, and dentists who have done so have risked their careers.

Numerous state dental boards, including those in Georgia, Iowa, North Carolina and Pennsylvania, have adopted similar prohibitions and enforced them by revoking or threatening to revoke the licenses of dozens of dentists specializing in the safe removal of mercury fillings, charging they made false advertising claims in describing the compounds as hazardous. Some dentists lost their licenses.

In 2008, as the FDA considered whether mercury fillings were devices warranting tighter controls, the dental association went so far as to argue that no safety warnings should be issued, not even for pregnant women and children under 6, because research had yet to prove the fillings to be dangerous.

The FDA posted such a warning on its website for about a year as part of a settlement with consumer lawyers but removed it in 2009, when the agency upheld the mercury products’ safety.

Nonetheless, growing numbers of dentists have abandoned mercury fillings, in part because patients prefer more cosmetically appealing alternatives.

The number of mercury compounds placed in Americans’ teeth has fallen steadily, from 157 million in 1979 to 96 million in 1990 and perhaps to under 20 million in 2015, according to claims data from Delta Dental, the nation’s largest dental insurer, with 68 million members and a 34 percent share of the market.

The trend has been aided by a narrowing price gap between mercury and resin fillings, whose durability also has improved. Composites cost about 25 percent to 28 percent more than mercury fillings, said Bill Kohn, chief science officer for Delta Dental. However, safety concerns also have arisen about some resin products.

Even a ban on mercury fillings — like bans already imposed in Sweden, Denmark, Norway, Finland and Japan — wouldn’t eradicate the potential health risks in the United States anytime soon.

According to the last U.S. government estimate, in 2004, 181 million Americans carried 1.46 billion mercury restorations in their teeth.

Much of that mercury, once estimated by the EPA to total 1,200 tons, could add to the environmental harm if there were to be continuing increases in the percentage of people opting to have their bodies cremated when they die. By 2025, incineration of corpses could send as much as 12 tons of mercury per year into the air, according to an analysis by the Vermont-based Mercury Policy Project, an environmental group.

The University of Washington’s followup study of genetic variants, known as polymorphisms, in children at the Casa Pia School in Lisbon, Portugal, could help solve the mystery of why some people seem to suffer serious effects from mercury fillings and others do not.

“We’ve clearly demonstrated at least a dozen very common genetic polymorphisms make worse the effects of mercury on some behavioral processes in children,” Woods, a recently retired University of Washington toxicologist who helped lead the research, said in a phone interview.

Men and boys are likely more susceptible, the researchers found, because girls in the study generally excreted more mercury in their urine, suggesting their immune and hormonal systems were better able to protect them from the toxin.

Echeverria, the Battelle researcher, said that while the observed effects were subtle, children in the study with genetic variants were increasingly impaired as their mercury exposures rose.

“If you have mercury in your fillings, you’re exposed to it for your entire life,” Woods said. “It gets to the point where it can override your ability to excrete mercury. The rest of it backs up and can bio-accumulate, especially in your brain.”

The American Dental Association has sought to play down the genetic findings.

Its science division rated the University of Washington team’s work “of medium quality” and said research on the subject has produced inconsistent results.

However, in a letter to consumer lawyers in January 2015, the FDA described the study as “well conducted” and said it offers evidence people with genetic abnormalities “may be at a higher risk for adverse health effects” from mercury fillings. The evidence isn’t yet strong enough to justify banning the compounds, the agency said.

The European Commission’s Scientific Committee on Emerging and Newly Identified Health Risks wasn’t so tentative. It advised dentists in the European Union’s 28 member countries to consider alternatives, because patients’ “genetic variants appear to impart increased susceptibility to mercury toxicity.”

James Love, a Tulsa, Oklahoma, consumer lawyer also fighting for a mercury ban, called the FDA’s inaction “a clear dereliction of duty” that fuels beliefs the agency “is the puppet of industry and has abdicated its role as the protector of the public.”

Dentists’ discharges of mercury-tainted debris first drew attention around 2002, when analyses concluded their offices were producing about half of the toxin in public waste streams.

In 2005, a study funded by the dental association concluded that U.S. dentists were using about 35 tons of mercury each year, of which about 6.5 tons was channeled into sewer systems. The EPA now puts that figure at 4.4 tons.

As a naturally occurring element, mercury cannot be destroyed, so its disposal poses a daunting challenge.

At wastewater treatment plants, most of the mercury settles into tons of sewage sludge, portions of which are incinerated, dumped into landfills or spread as fertilizer over cropland, a method environmentalists say puts the toxin in the food chain.

“Mercury is like a hot potato,” said Michael Bender, director of the Mercury Policy Project. “The dentists don’t want it, so they dump it down the drain. The sewage sludge facilities can’t handle it, so they allow it to be dumped into the sludge, and the community incinerators pick up the tab. It’s not costing the lazy wastewater utilities. It’s an externalized cost of dentistry.”

They say the solution to pollution is dilution. But you can’t dilute mercury. It never goes away. Scientists say it ping pongs from the atmosphere, into the water and back into the air. These folks with the smoke and mirrors, they’d like you to think the mercury disappears.

Michael Bender, director of the Mercury Policy Project

Many dental clinics’ current efforts to collect mercury waste get low grades.

About half of dentists use dry vacuums to suction large chunks of mercury from patients’ mouths and deposit them into tanks, one former dental industry figure said.

But a valve at the bottom of many of the tanks is set up to automatically open at day’s end, when the dental staff turns off the vacuum lines, said this person, who spoke on condition of anonymity to avoid damaging relationships. If a dentist failed to first empty his tank into hazardous waste receptacles, the toxic brew goes into sewer lines. Asked about this allegation, two EPA officials did not dispute it.

The American Dental Association has walked a narrow line between publicly supporting efforts to contain dental mercury waste and quietly seeking to put off regulations.

In 2003, the association adopted “best practices” to guide its members’ handling of mercury waste. It did not include a recommendation that dentists install separators until 2007, after it became possible to recycle the mercury.

We have worked with the EPA on a separator rule for years. We support the proposal in its essence and have offered only constructive comments.

American Dental Association

Curt McCormick, who worked for 20 years in the EPA’s Denver regional office, said he began in 2004 to advise communities with high mercury levels in their treated wastewater to require dentists to install separators. That brought an emailed rebuke from Jerry Bowman, then an assistant counsel for the dental association. At a meeting that December in Washington, Bowman complained about McCormick’s activities to Ben Grumbles, chief of the EPA’s Office of Water.

Weeks later, Bowman wrote Grumbles that the regional office had “not shifted its position one inch” and expressed frustration the agency wasn’t accepting a voluntary approach.

On Dec. 29, 2008, three weeks before Barack Obama was sworn in as president, the dental association and a seemingly unlikely ally, a trade group representing nearly 300 of the nation’s big-city wastewater treatment utilities, signed a deal with Grumbles, acting on behalf of departing President George W. Bush’s EPA. It gave dentists time to address the mercury pollution voluntarily.

Within a year, Obama’s EPA concluded the voluntary route wasn’t working.

Ken Rosenblood, a Los Angeles entrepreneur who for 20 years sold equipment to help dental offices remove toxins, said he experienced the problem firsthand. Hundreds of times, he said, he heard this refrain from dentists: “If the law doesn’t require it, I’m not going to do it.”

In California’s Sacramento County, dentists have accounted for 42 percent of the annual 40 to 67 pounds of mercury in sewage since 2010, county officials said. Over the last two years, the county sent circulars beckoning about 800 dentists to join a program to install separators voluntarily. Ten dentists signed up.

McCormick said many cities use testing methods not powerful enough to detect traces of mercury, so they don’t know how much is in their waste streams.

It was September 2014 before the EPA formally proposed a rule requiring the nation’s 110,000 dental offices to buy mercury separators and submit to waste disposal policing by public utilities. The agency estimates that about 40 percent, or 44,000 of the nation’s dental offices, have dealt with their mercury problems, most located in 13 states that have lurched ahead of the EPA and now require separators.

The dental association’s newfound ally, the National Association of Clean Water Agencies and its members, rained negative comments onto the EPA’s rule-making docket, complaining that they would be saddled with a huge administrative burden and that the EPA’s $49 million cost projection “greatly underestimates the cost of the rule.”

The association told McClatchy that separators “primarily shift the point of capture from a treatment plant to the office. In either case, the amalgam is captured.” It did not explain how this occurs, since tons of mercury wind up in sewage sludge.

EPA spokeswoman Monica Lee declined to say whether the agency, which has imposed tough curbs on hundreds of coal-fired power plants to cap emissions of greenhouse gases and mercury, will act by next June to compel dentists to limit mercury discharges, leaving enough time for the rule to take effect before Obama leaves office.

The dental association says it supports the Minamata treaty, which directs each country to choose at least two of nine options for phasing down mercury fillings.

But in 2011, as the treaty negotiations heated up, Raymond Gist, then the president of the dental association, sent a letter urging the State Department to make the Food and Drug Administration, not the EPA, the lead U.S. negotiator over the environmental pact. FDA officials not only had defended mercury fillings, but they also never required manufacturers of dental fillings to file statements assessing the environmental impacts of their products.

The next year, an outside lobbyist hired by the association reported he had been paid $40,000 to “oppose” the treaty.

A couple of weeks after its 2013 signing, Charles Norman III, then the dental association president, issued a statement praising the treaty, emphasizing first that it “upholds the use of dental amalgam, a durable, safe, effective cavity-filling material.”

CORRECTION: An earlier version of this story wrongly described the mercury issue that was drawing concerns from EPA’s Denver regional office in 2004. It should have said treated wastewater.

Greg Gordon: 202-383-0005, @greggordon2

Related stories from McClatchy DC

  Comments