Mercury vapour limits exceeded in new study

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Amalgam and pregnancy: Mercury vapour limits exceeded in new study

In a recent study, almost one-third of pregnant women were exposed to mercury vapour levels from dental amalgam that surpassed the safety limits. (Image: Alexey Fursov/Shutterstock)

LAKELAND, Fla., US: Although an increasing number of dentists and patients are choosing resin composites as restorative materials, amalgam is still widely used despite its disadvantages, such as poor aesthetics, harm to the environment and evidence that it may have harmful health effects on human health. Adding to the existing evidence on amalgam toxicity, a new study examined the impact of mercury vapour exposure from amalgam among pregnant American women and found that a large number of cases exceeded the safety limits set by the US Environmental Protection Agency. The finding is especially troubling in the light of the heightened risk of harmful effects on the foetus caused by exposure to mercury vapour during pregnancy.

This study used data from the 2015–2020 Centers for Disease Control and Prevention National Health and Nutrition Examination Survey, which analysed mercury vapour exposure in 1,665,890 pregnant women. In the study, the researchers examined the association between the number of amalgam fillings and the daily amount of mercury excreted in urine. They then compared daily vapour exposure from amalgam to mercury vapour safety limits.
The findings showed that approximately 36% of the pregnant women had one or more tooth surfaces restored with amalgam and that those who had amalgam fillings had an approximately 2.5-fold higher median daily urinary mercury excretion compared with women without amalgam fillings. The researchers reported that about 28% of pregnant women in the study were exposed to mercury vapour levels from dental amalgam that surpassed the least stringent safety limit, set by the US Environmental Protection Agency, and around 36% were exposed to levels that exceeded the more stringent limit, established by the California Environmental Protection Agency.
The International Academy of Oral Medicine and Toxicology called the study results alarming. The academy’s president, Dr Charles Cuprill, said in a press release: “The findings of this study underscore the need for heightened awareness of the risks to dental patients and policy shifts regarding the use of dental amalgams.” He added: “FDA [US Food and Drug Administration] warnings on amalgam are not enough. Mercury amalgam dental fillings should be banned by the FDA as they pose a serious risk to the health of all individuals who have amalgam fillings, especially pregnant women and those of reproductive age.”
In light of the findings, the researchers believe that efforts should be made to minimise or completely avoid the use of dental amalgam during pregnancy and in women of childbearing age. Additionally, they noted that future research should investigate the potential negative impacts of exposure to mercury vapour on pregnancy outcomes.

Amalgam ban in the EU

After years of gradual phase-down and stringent restrictions on amalgam fillings worldwide, the European Parliament has recently announced that it will completely ban dental amalgam starting from 1 January 2025. Given the wide use of amalgam in the EU, the ban is expected to result in supply chain issues in some countries.
The study, titled “Estimated mercury vapor exposure from amalgams among American pregnant women”, was published online on 5 February 2024 in Human and Experimental Toxicology.

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