Mercury Exposure from Tuna Fish vs. Silver Dental Amalgam Fillings

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Today, the most widespread human exposures to mercury are from silvery amalgam tooth fillings, the thimerosal ethylmercury in certain vaccines, and the methylmercury–– mostly from eating fish. I talked about the mercury in vaccines compared to that of fish; what about the amalgam fillings?

Every time most of us bite down, a small amount of mercury is released. And, by most, I mean like 60% of Americans. About 91 million adults in the United States have at least one amalgam filling. Based on the number of fillings, about 86 million Americans exceed the California Environmental Protection Agency’s safety limit for daily exposure to mercury vapor, and about 16 million people blow past the more relaxed safety limit from the national EPA. So, in 2020, the U.S. Food and Drug Administration recommended that certain high-risk groups should not get amalgam fillings. This includes children, and women who are even just planning on getting pregnant.

The FDA is not recommending anyone remove existing amalgam fillings, though, because when you try to get them out, you get a spike in mercury release despite all feasible controls that’ve been used to minimize mercury exposure.

Thankfully, amalgam use has recently dropped by 73%. But most people continue to eat fish. In children, frequency of fish consumption was the most robust predictor of high mercury levels growing out in their hair, rather than the number of mercury-containing fillings. Even among dentists, mercury concentrations in hair and blood were largely explained by fish consumption, rather than the number of amalgams they worked with weekly.

The measured levels of amalgam-derived mercury in brain, blood, and urine are shown to be consistent with absorbing about two micrograms a day. That’s high enough that the FDA is like, maybe kids or women who want to have kids shouldn’t get them. But a single can of tuna has 60 micrograms. Sadly, the amount of mercury in tuna hasn’t changed much over the last half century. So, having amalgam fillings is like eating one can of tuna every two months.

There have been more than a hundred risk/benefit analyses published on fish and other seafood looking at the nutrient versus contaminant tradeoffs. Fish consumption provides some nutrients, but all fish also provide methylmercury, a known neurotoxin. Mercury may be a cardiovascular toxin as well, which may explain why there’s been a failure to consistently observe beneficial effects of fish consumption.

Sure, dietary exposure to mercury may harm child development, but if we cut down on fish, the argument goes, we could get fewer omega-3s. Researchers got out their calculators and figured that in a city about the size of New York, if pregnant mothers ate lots of fish, because omega-3s like DHA are so beneficial to brain development, we would expect to see an improvement in 209,000 years of children’s lives (what are called quality-adjusted life years). But, at the same time, the mercury in that very same fish would damage 203,000 of children’s life years. So, they did the math, and it comes out positive by a hair, and we hear on the news such and such medical authority says the benefits outweigh the risks: eat fish.

Now, this does not take into account the dioxins, the PCBs, and the other contaminants that may tip the scale away from eating fish. But, more importantly, why accept any risk at all? By getting DHA from pollutant-free sources, we can get all the benefit, with none of the risks. All the benefit, without the hundreds of thousands of life years of brain damage.

This is like when reviews on dairy conclude milk does more good than harm in part because of all the calcium, despite links to diseases like Parkinson’s and prostate cancer––as if the only source of calcium on the planet were dairy. Where do you think cows get calcium in the first place? From plants. And, the same with omega-3s like DHA. Where do you think the fish get it? Plants. And, we can, too—tiny little plants called microalgae, and so we can skip the middle fish, and get it mercury-free from algae-based supplements.

Please consider volunteering to help out on the site.

• Roy S, Aggarwal A, Dhangar G, Aneja A. Mercury in vaccines: A review. Glob Vaccines Immunol. 2016;2(1).
• Mercury in Dental Amalgam. US EPA. February 6, 2025.
• Geier DA, Geier MR. Dental amalgam fillings and mercury vapor safety limits in American adults. Hum Exp Toxicol. 2022;41:9603271221106341.
• FDA Issues Recommendations for Certain High-Risk Groups Regarding Mercury-Containing Dental Amalgam. US FDA. September 24, 2020.
• Warwick D, Young M, Palmer J, Ermel RW. Mercury vapor volatilization from particulate generated from dental amalgam removal with a high-speed dental drill - a significant source of exposure. J Occup Med Toxicol. 2019;14:22.
• Bartelt K, Lipman R, Estrich C, Sandmann D, Lindemann P, Piff A. Mercury-Containing Amalgam Fillings Account for Less Than 6% of Posterior Tooth Fillings in 2022. Epic Research. 2023.
• Dunn JE, Trachtenberg FL, Barregard L, Bellinger D, McKinlay S. Scalp hair and urine mercury content of children in the Northeast United States: the New England Children's Amalgam Trial. Environ Res. 2008;107(1):79-88.
• Goodrich JM, Chou HN, Gruninger SE, Franzblau A, Basu N. Exposures of dental professionals to elemental mercury and methylmercury. J Expo Sci Environ Epidemiol. 2016;26(1):78-85.
• Mackert JR Jr, Berglund A. Mercury exposure from dental amalgam fillings: absorbed dose and the potential for adverse health effects. Crit Rev Oral Biol Med. 1997;8(4):410-436.
• Mercury Levels in Commercial Fish and Shellfish (1990-2012). US FDA. February 25, 2022.
• Médieu A, Point D, Sonke JE, et al. Stable tuna mercury concentrations since 1971 illustrate marine inertia and the need for strong emission reductions under the minamata convention. Environ Sci Technol Lett. 2024;11(3):250-258.
• Thomsen ST, Assunção R, Afonso C, et al. Human health risk-benefit assessment of fish and other seafood: a scoping review. Crit Rev Food Sci Nutr. 2022;62(27):7479-7502.
• Yaktine AL, Nesheim MC, James CA. Nutrient and contaminant tradeoffs: exchanging meat, poultry, or seafood for dietary protein. Nutr Rev. 2008;66(3):113-122.
• Myers GJ, Davidson PW, Strain JJ. Nutrient and methyl mercury exposure from consuming fish. J Nutr. 2007;137(12):2805-2808.
• Hu XF, Lowe M, Chan HM. Mercury exposure, cardiovascular disease, and mortality: A systematic review and dose-response meta-analysis. Environ Res. 2021;193:110538.
• Lee DH, Jacobs DR Jr. Inconsistent epidemiological findings on fish consumption may be indirect evidence of harmful contaminants in fish. J Epidemiol Community Health. 2010;64(3):190-192.
• Oken E, Bellinger DC. Fish consumption, methylmercury and child neurodevelopment. Curr Opin Pediatr. 2008;20(2):178-183.
• Guevel MR, Sirot V, Volatier JL, Leblanc JC. A risk-benefit analysis of French high fish consumption: a QALY approach. Risk Anal. 2008;28(1):37-48.
• Zhang X, Chen X, Xu Y, et al. Milk consumption and multiple health outcomes: umbrella review of systematic reviews and meta-analyses in humans. Nutr Metab (Lond). 2021;18(1):7.
• Omega-3 Fatty Acids - Health Professional Fact Sheet. National Institutes of Health. August 22, 2025.

Motion graphics by Avo Media

• cardiovascular disease
• children
• dental health
• fish
• mercury
• pregnancy
• tuna
• vaccines