DAMS Mercury Fact Sheet #2

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Environmental Effects of Mercury from Amalgam

  1. Human excretion into sewers by those with amalgam dental fillings along with dental office amalgam waste have been documented to be the largest source of mercury into sewers and septic tanks.
  2. All sewer plants in the U.S. have high levels of mercury and all sewer sludge has dangerous levels of mercury (generally 1 to 3 ppm).
  3. Dental amalgam fillings are a major source of mercury going into rivers, lakes, and bays, both from dental offices and human waste in home and office sewers. Dentistry is the third largest user of mercury in the U.S., using 45 tons per year, most of which ends up in the environment.
  4. Mercury pollution is widespread in U.S. rivers, lakes, and bays, with dangerous amounts of mercury commonly found in freshwater and saltwater fish. Over 50% of Florida’s rivers and lakes, and most bays, have warnings regarding eating the fish. Over 33% of all U.S. lakes have fish consumption warnings: 15% of all U.S. river miles, 90% of Atlantic coastal miles, and 100% of all Gulf coastal miles. Most Gulf Coast salt water predator fish species have high levels of mercury (above the EPA/FDA warning level).
  5. Mercury is the most toxic substance commonly encountered and is adversely affecting the health of millions of people in the U.S.
  6. If sewer sludge is incinerated, most of the mercury goes into emissions.
  7. Crops grown on land using sewer sludge pick up high levels of mercury. Soil bacteria in landfills and land spread sludge areas methylate mercury to methyl mercury, which is released in methane and landfill gas in high levels. High levels of mercury are being found in rain all over the U.S.
  8. Dental amalgam fillings are the largest source of mercury in most people, and levels of mercury exposure from amalgam commonly exceed government health guidelines, with high levels in human excretion wastes documented.
  9. The level of mercury in all sewer plants in the U.S. exceeds the Environmental Protection Agency (EPA) proposed limit for mercury in water due to the large amount from amalgam in sewers from dental offices, homes, and businesses.
  10. Crematoria emissions commonly violate mercury air emission standards and are a significant source of mercury emissions due to mercury in amalgam fillings. Amalgam related air emissions exceed coal plant emissions in the U.K.
  11. Due to the high mercury releases from dental offices, most European countries require amalgam separators. The U.S. still has no regulations on this source of mercury. Due to the major environmental effects of mercury from amalgam fillings, plus the known adverse health effects, most Japanese dental schools no longer teach the use of mercury amalgam fillings. Several other countries have voted to ban amalgam or issued warnings regarding its use, as have several U.S. states.


    Mercury is one of the most toxic substances commonly encountered and. according to government agencies, causes adverse health effects in large numbers of people in the U.S. The extreme toxicity of mercury can be seen from documented effects on wildlife by very low levels of mercury exposure. The amount of mercury in the marine environment is increasing 4.8% per year, doubling every 16 years. Some Florida panthers that eat birds and animals that eat fish containing very low levels of mercury (about 1 part per million) have died from chronic mercury poisoning. Since mercury is an estrogenic chemical and reproductive toxin, the majority of the rest cannot reproduce. The average male Florida panther has higher estrogen levels than females, due to the estrogenic properties of mercury. This is true for some other animals at the top of the food chain, such as polar bears, beluga whales and alligators, which are affected by mercury and other hormone disrupting chemicals. Mercury in whale meat has been found to be high enough to cause acute toxicity from one meal. Several liver samples contained over 1000 ppm mercury – over 2000 times the Japanese health standard. Muscle samples contained 2.5 to 25 times the health standard. The Japanese government’s limit for mercury contamination is 0.4 micrograms per gram. According to the U.S. EPA, the maximum advisable concentration of methyl mercury in fish and shellfish tissue to protect consumers among the general population is 0.3 ppm. Several European countries including Sweden have banned use of amalgam fillings, with the environmental releases being a major factor.

    Mercury has been found to be so toxic that the drinking water standard for mercury is 2 parts per billion(ppb). But the EPA has found that because mercury bioaccumulates even lower standards appear to be needed to protect from accumulation in fish and wildlife and human health. Lower standards have been proposed or adopted in many areas. The Great Lakes Initiative Wildlife Criteria calculated a limit of 1.3 nanograms per liter(ng/L) to prevent accumulation in fish and wildlife, while the GLI Human Health Criteria is 3.1 ng/L (parts per trillion). The EPA Fish Tissue Methyl Mercury-based Criteria for rivers is 7.8 ng/L and 3.5 ng/L for lakes. The California Toxics Rule Saltwater Criteria is 25 ng/L. The EEU limit on mercury in sewers is 50 micrograms per liter.

    The average amalgam filling has more than ½ gram of mercury and has been documented to continuously leak mercury into the body of those with amalgam fillings due to the low mercury vapor pressure and galvanic current induced by mixed metals in the mouth. Amalgam has been well documented as the number one source of mercury in most people and to commonly cause serious adverse health effects. Amalgam has also been documented as the largest source of methyl mercury in most people, since mercury vapor and inorganic mercury have been shown to be methylated to methyl mercury in the mouth and intestines by bacteria, yeasts, and other methyl donors. Mercury has also been found to be methylated in dental office disposal and sewer systems at levels orders of magnitude higher than in lakes and rain.

    Because of the extreme toxicity of mercury, only ½ gram is required to contaminate the ecosystem and fish of a 10 acre lake to the extent that a health warning would be issued by the government to not eat the fish. Over half the rivers and lakes, along with most bays in Florida have such health warnings, banning or limiting the eating of fish, and most other states and 4 Canadian provinces have similar health warnings. Wisconsin has fish consumption warnings for over 250 lakes and rivers, and Minnesota even more, as part of the total of over 50,000 such lakes with warnings (over 33% of all significant U.S. lakes) and 15% of all U.S. river miles. All Great Lakes, as well as most coastal bays and estuaries, carry similar health warnings, with 90% of Atlantic coastal miles and 100% of Gulf coastal miles covered by fish mercury warnings.

    Nationwide, the dental industry is the third largest user of mercury, using over 45 tons of mercury per year, and most of this mercury eventually ends up in the environment. Amalgam from dental offices is by far the largest source of mercury (over 35% of the total) into sewers and sewer plants, with mercury from replaced amalgam fillings and crown bases the largest source. When amalgam fillings are removed by standard practice methods using primary and secondary solids collectors, approximately 60% of the amalgam metals by weight end up in sewer effluent. As much as 10% of prepared new amalgam becomes waste. This mercury also accumulates in building sewer pipes and septic tanks or drain fields, creating toxic liabilities. Unlike Canada and most European countries, which have much more stringent regulation of mercury that requires amalgam separators in dental offices, the U.S. does not and most dental offices do not have them. The discharge into sewers at a dental office without amalgam separators is between 56 and 270 milligrams per day, per amalgam-using dentist. (Some studies have found much higher levels for some offices.) For the U.S., with approximately 170,000 dentists working with amalgam, this would be from 2500 kg/yr to 12,000 kg/yr (3 to 13 tons/year) of mercury into sewers, and thus into streams, lakes, bays, and sewer sludge. In Canada, the annual amount discharged is about 2 tons per year, with portions ending up in waters/fish, landfills, cropland, and air emissions.

    Studies in Michigan, California, and Washington estimated that dental mercury is responsible for approximately 12 to14% of mercury discharged to streams. An EPA study found that dental office waste was responsible for similar levels of mercury in lakes, bays, and streams in other areas throughout the U.S. A Canadian study found similar levels of mercury contribution from dental offices into lakes and streams, and surveys of dental office disposal practices found the majority violated disposal regulations and that dangerous levels of mercury are accumulating in pipes and septic tanks from many offices. Dental mercury amalgam has been documented to be highly bioavailable in water.

    The total discharge into sewers from dental amalgam at individual homes and businesses is second only to that from dental offices, since the average person with amalgam fillings excretes approximately 40 micrograms per day of mercury. This has also been confirmed by medical labs such as Doctors Data Lab in Chicago and Biospectron in Sweden, which do thousands of stool tests per year. It is also consistent with studies measuring levels in residential sewers by municipalities. In a Finnish study, over 20 % of those with amalgam excrete so much to home sewers that the EEU standard for mercury in sewers(50 ug/L) is exceeded. The amount of mercury excreted on average doubled for each additional 10 amalgam surfaces. The AMSA study adopted the conservative estimate of 28 micrograms per day for the average person with amalgam and 17 micrograms for the average of all, both with and without amalgam. In the U.S., this amounts to approximately 2800 to 5500 kilograms per year into sewers, or from 3 to 6 tons per year. Over 3 tons of mercury flows into the Chesapeake Bay annually from sewer plants, with numerous resulting fish consumption advisories for that area. It is a similar case in other areas. Thus, the amount of mercury being excreted from dental amalgam is more than enough to cause dangerous levels of mercury in fish in most U.S. streams into which sewers empty. Studies by Oak Ridge National Laboratory (U.S. Dept. of Energy) and others have confirmed high levels of mercury in sewers and sewer sludge (generally 1 to 3 ppm in biosolids). Publically owned treatment works ( POTWs) do not have equipment to remove mercury in sewers other than any pretreatment requirements imposed by sewer districts. Mercury wastes are incompatible and must be removed at the source. In general, POTWs are not equipped to remove or treat toxic chemicals.

    MCES found that dental offices were responsible for over 40% of Minneapolis sewer mercury and excretion from those with amalgam for over 80% of domestic mercury. According to an EPA study, the majority of U.S. sewerage plants cannot meet the new EPA guideline for mercury discharge into waterways that was designed to prevent bioaccumulation in fish and wildlife due to household sewer mercury levels. The EPA discharge rule had been reduced due to a National Academy of Sciences report of July 2000 that found that even small levels of mercury in fish result in unacceptable risks of birth defects and developmental effects in infants.

    ORNL studies have found that crops grown on land using land spread sewer sludge pick up high levels of mercury, and soil bacteria methylate inorganic mercury into methyl mercury, which is released into the air or landfill gas at high levels. Sixty percent of the 5.6 million tons of sewage sludge generated each year are used for land application. The ORNL studies estimate that emissions of mercury from sludge amended soil amounts to from 5 to 6 tons of mercury per year. Most dental amalgam waste from dental offices either goes into landfills or is incinerated. Much of the sewer sludge is also incinerated. Most of the mercury in materials that are incinerated goes out in the emissions, as most incinerators have no controls to remove mercury. High levels of mercury, including the very toxic organic forms, are being measured in rainfall throughout the U.S. High levels of the extremely toxic dimethyl and methyl mercury forms of mercury are being found in landfill gas coming from landfills and appear to be a significant source of some of this. Bacteria in landfills have been found to be methylating elemental and inorganic mercury to the organic forms. Dental amalgam waste and mercury from human sewer sludge are major sources of mercury in some landfills, and sludge is also used in landspreading on farms and other areas. Health Canada has also documented similar information on mercury emissions from amalgam and sewer sludge to waterways, crops, and air.

    Additionally, cremation of those with amalgam fillings adds to air emissions and deposition onto land and lakes. A study in Switzerland found that in that small country, cremation released over 65 kilograms of mercury per year as emissions, often exceeding air mercury standards, while another Swiss study found mercury levels during cremation of a person with amalgam fillings as high as 200 micrograms per cubic meter (considerably higher than U.S. mercury standards). The amount of mercury in the mouth of a person with fillings was, on average, 2.5 grams – enough to contaminate five 10 acre lakes to the extent there would be dangerous levels in fish. A Japanese study estimated mercury emissions from a small crematorium there as 26 grams per day. A study in Sweden found significant occupational and environmental exposures at crematoria, and since the requirement to install selenium filters, mercury emission levels in crematoria have been reduced 85%. For the 70% of people in Britain who die and end up with their bodies being cremated, the mercury escapes into the atmosphere and contaminates waterways, soil, wildlife, and food. Crematoria now contribute 16% of all the mercury released by industry and power plants in Britain, with levels projected to soon exceed emissions by power/industrial plants. The 440,000 people cremated in Britain every year are estimated to discharge 1300kg of mercury A study assessing hair mercury in a group of staff at some of the 238 British crematoriums found that the groups’ hair mercury levels were significantly greater than that of controls. Government guidance calls on them to introduce new flue cleaning measures to help achieve a statutory target of a 50 per cent reduction by 2012.
    Documentation of these and other studies are available from DAMS at amalgam.org.

    DAMS is currently working with thousands of people in the U.S. dealing with serious health effects caused by exposure to mercury from amalgam and urges everyone to find out more about this major problem and to get involved in resolving these health safety issues. DAMS can provide information and help to anyone who is interested or who thinks they might have health problems related to their amalgam fillings.

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