No Harm Found in Amalgam Fillings
2 Studies Show No Ill Effects From Mercury in Kids' Dental Fillings
Debate Far From Over continued...
Now he warns that we just don't know enough about mercury to say it's safe to put into kids' mouths.
In an editorial accompanying the McKinlay and DeRouen reports, Needleman agrees that the studies show no obvious problems in children who get amalgam fillings. But he argues that the studies can't account for rare side effects. Because so many children get amalgam fillings, even a side effect that struck one in 100 children would affect hundreds of thousands of kids.
"These are good studies, but they are not enough to assert that amalgam in fillings is safe," Needleman tells WebMD. "I know people will parade this as showing there is no harmful effect of fillings. But I have heard this argument made with other toxins, too."
Needleman remembers being taught that lead was toxic only at blood levels six times higher than those now believed to be safe. And, he says, there's troubling data that even this much lead might be harmful. Mercury in dental fillings gives him a troubling sense of déjà vu.
"As better studies are done, harmful effects will become visible at doses of mercury now considered safe. I think that will be inevitable," Needleman says. "The question of whether amalgam fillings are safe is still open. But if my children needed fillings, I would use an alternative."
Amalgam vs. Resin Composite
The resin composite tested in the McKinlay and DeRouen studies did not contain mercury. But it contained several other chemicals -- and nobody knows whether these chemicals are safe in the long term.
"We know even less about that than about the safety of amalgam," DeRouen says. "Yes, there is a small percentage of kids that might react negatively to amalgam -- but there is no data on that. What we do have data on, is that in these kids we studied, we did not see any safety differences between amalgam and resin-composite fillings. While there could be rare events linked to amalgam, there is no hint of it here."
McKinlay says if there is a danger from amalgam fillings, it should be most apparent in growing children.
"We look at the group that would be most vulnerable to toxic effects of mercury from amalgam -- and we are not seeing it," she says. "Therefore the chance it is safe, in children going forward, is probably a good bet. ... There is always going to be the rare exception to any rule. But we now have real information on the safety of amalgam from two very well-designed trials. We had none before this. This is the only evidence available."