New Studies Indicate Florida and the Gulf Coast have a Major Mercury Problem, with high levels of mercury in: saltwater fish and shellfish, freshwater fish, rain, all sewer plants and sewer sludge, crops where sludge is spread, many adults and children, and widespread adverse health effects B. Windham (Ed.)
1. Studies document that Florida Saltwater fish, shellfish, and freshwater fish have high levels of mercury in large parts of the state.
2. There are fish consumption warnings/limits for king mackerel and shark in all parts of the state and consumption warnings on jack crevalle, spotted sea trout, Spanish mackerel, gafftopsail catfish, and lady fish in some areas. A study found that spotted sea trout in Eastern Florida Bay commonly exceed the 1.5 ppm no consumption mercury level.
3. Five Gulf saltwater species have average mercury levels on tested samples higher than the FDA action level for fish; 27 species have average mercury test levels above the FDA warning level for mercury in fish with some above the action level, and 16 species of fish as well as crabs, oysters and shrimp have average test levels near the warning level or some tested above the FDA action level. All of these have levels about the EPA health criterion for methylmercury in fish and shellfish tissue.
4. Studies have found that people who eat Gulf Coast fish at least once per week usually have dangerous levels of mercury. 29% of a coastal sample ate fish at least once per week. Studies have found adverse health effects for those who eat fish at below the FDA warning level.
5. Studies have found that fish and shellfish that feed near offshore oil and gas platforms have higher levels of mercury than other areas.
6. Studies have found that freshwater predator fish such as bass, pickerel, and bowfin have high levels of mercury in most of the state, with fish consumption warnings issued. 8 other species have average test levels near the warning level or some tested above the FDA action level.
7. Studies have found that predator species such as wading birds, alligators, and Florida Panthers whose diet depends on fish have high levels of mercury, and adverse health and reproductive effects. Livers of cormorants in Florida Bay were found to have mercury levels as high as 250 ppm, higher than any previously tested in Florida.
8. Studies by the Oak Ridge National Laboratory(ORNL) have found high levels of dangerous forms of mercury in landfill gas being emitted from Florida landfills and from lands where sewer sludge is spread, due to methylation of mercury to methyl and dimethyl mercury by soil bacteria.
9. All sewer plants and sewer sludge in Florida have dangerous levels of mercury , which is a major source of mercury in fish and source of mercury in crops and rain where sewer sludge is spread. High levels of mercury are being found in rain throughout Florida and the U.S., including methyl mercury from landfills and land spreading. The most common source of these high mercury levels was found to be human excretion into home and business sewers from those with amalgam dental fillings.
10. The largest source of mercury in most adults is amalgam dental fillings, but food is a significant source in those who eat fish or shellfish frequently.
11. The 3 main sources of mercury in Florida infants are mercury thimerosal in vaccinations; mercury from mother's amalgam dental fillings transferred across the placenta to the fetus or through mother's milk to the infant; and mercury from fish. These are all significant sources in Florida.
12. The National Academy of Sciences found that 50% of U.S. pregnancies result in birth defects or infants who have significant developmental effects such as ADD, dyslexia, mood or anxiety disorders, learning disabilities, eczema, asthma, or other chronic allergies or health problems. Studies document that the majority of these are due to toxic exposures, with the most common and significant being mercury.
13. The U.S. CDC and National Academy of Sciences found that at least 10% of U.S. womenhave mercury levels high enough to cause developmental neurological conditions inprenatally exposed infants; this may be higher in Florida due to higher than averagemercury levels in fish and high levels of fish consumption. The tests used mainly measured methyl mercury, and did not significantly assess exposure levels from dental amalgam which is the largest source of mercury in many adults or infant vaccinations which are the largest sources in infants.
14. Mercury exposure is cumulative from the various sources and bioaccumulates over time, with different sources more significant in different individuals. Health effects are synergistic between the different forms of mercury exposure and other toxic exposures, and depend also on individual susceptibility which varies widely due to immune reactivity and systemic detoxification differences of individuals.
15. Levels of mercury in South Florida Everglades fish and wildlife declined at least 80% after mercury emissions from South Florida incinerators were required to control emissions.
High levels of mercury have been found in the rain throughout Florida
and the U.S.(34,16,24), resulting in accumulation of mercury in the
environment, water bodies, fish, wildlife, and people of Florida. Mercury in Florida rainfall measured more than five times the federal health standard for lakes(34). The largest sources of emissions have been found to be coal power plants, incinerators, kilns(16). The level of mercury in rain ranged from 1.3 to 81.2 nanograms per liter depending on location and weather conditions, with an average of 12.6. This resulted in depostition of and average annual depostion of about 17.6 micrograms of mercury per square meter, much higher than the U.S. EPA health criteria to prevent harm to wildlife and humans(33). The Electric Power Research Institute(2) and other studies have found that only ½ gram of mercury is required to contaminate all predator fish in a 10 acre lake to the extent that fish consumption warnings are required, and enough mercury is being released into the environment of Florida to raise levels in all fish to such a level.
Mercury has been found to be the most toxic substance commonly come in contact with, so toxic that the drinking water standard for mercury is 2 parts per billion(ppb). But U.S. EPA have found that because mercury bioaccumulates in the environment and fish, to protect from accumulation in fish and wildlife and thus human health even lower standards appear to be needed and lower standards have been proposed or adopted in many areas(13e). The Great Lakes Initiative Wildlife Criteria calculated needed to prevent accumulation in fish and wildlife is 1.3 nanagrams per Liter(ng/L) while the GLI Hunan Health Criteria is 3.1 ng/L(parts per trillion). The EPA Fish Tissue Methyl Mercury-based Criteria for lakes is 7.8 ng/L and for rivers is 18 ng/L. The California Toxics Rule Saltwater Criteria is 25 ng/L(13e,33,34).
According to Government agencies due to its extreme toxicity and common exposures, mercury causes adverse health effects in large numbers of people in the U.S.[1,14-16,21,28]. Based on widespread tests, the U.S. CDC estimates that approx. 16 % of women of childbearing age, 6 million women, have current mercury levels that would put fetuses at risk of developmental neurological problems(14), without considering other common sources of mercury in infants. The level affected is likely highly understated due to the fact that blood is known to not be a reliable indicator of mercury body burden and is not a good indicator of mercury vapor exposure from dental amalgams or dental office occupational exposure, which is higher in many people than mercury from fish.
Studies by EPA have found that the fetus on average has mercury levels 70% higher than the mother’s blood, putting large numbers of infants over the EPA health safety guideline of 5.8 parts per billion(14c). Studies by the National Academy of Sciences have found that 50 % of U.S. children have significant developmental conditions such as ADD, dyslexia, autism, learning disabilities, mood or anxiety disorders, eczema, asthma, chronic allergies, etc.(8), and studies have also documented that the majority of these are caused by toxics exposures, with mercury exposures being one of the most common and significant of these(8,14,15,20,21b,27,28).
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(6). A major factor in the extreme decline of wading birds in Florida is mercury exposure from eating fish and other fish predators are affected as well(7). However levels of mercury in wading birds and fish in the Everglades area have declined some since controls were mandated on incinerators a few years ago. Livers of cormorants in Florida Bay were found to have mercury levels as high as 250 ppm, higher than any previously tested in Florida(4b). 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(7). Since mercury is an estrogenic chemical and reproductive toxin, many of the rest cannot reproduce. The average male Florida panther has higher estrogen levels than females, due to the estrogenic properties of mercury(7). Similar is true of some other animals at the top of the food chain like polar bears, beluga and orca whales, and alligators, which are affected by mercury and other hormone disrupting chemicals.
Studies document that Florida Saltwater fish and shellfish have high levels of mercury in large parts of the state(4,5,9,12,3b). There are fish consumption warnings/limits for king mackerel and shark in all parts of the state and consumption warnings on jack crevalle, spotted sea trout, Spanish mackerel in several estuaries, and on gafftopsail catfish, and lady fish in Tampa Bay (4,9). Some areas such as North Florida Bay and offshore Tampa Bay have test levels higher than most other areas(4). A study found that spotted sea trout in Eastern Florida Bay commonly exceed the 1.5 ppm no consumption mercury level(4b).
Based on the tests that have been done, eight saltwater species(king mackerel, black grouper, cobia(ling), barracuda, bonita(little tunny), florida smoothhound, great while shark, tilefish) have average mercury levels on tested samples higher than the FDA action level of 1 part per million(ppm) for fish(4,5,12); 24 species had average mercury test levels above the FDA warning level(0.5 ppm) for mercury in fish(black drum, blacktip shark, bluefish, bonefish, bonnethead shark, bull shark, snook, greater amberjack, jack crevalle, ladyfish, lemon shark, red drum, rock bass, spanish mackeral, spotted bass, blackfin tuna, gag grouper, wahoo, bluefish, gafftopsail catfish, crevalle jack, ladyfish, and stone crab) , and 15 species of fish(blacknose shark, blue crab, grouper spainish, gulf flounder, permit, red grouper, sand trout, sheepshead, silver seatrout, southern flounder, tarpon, tripletail, white bass, yellow bass, yellow jack), as well as crabs, oysters and shrimp have average test levels near the warning level or some that tested above the FDA action level(4,12). Approximately 94% of all adult red drum from offshore waters adjacent to Tampa Bay contained mercury levels greater than or equal to the 0.5-ppm threshold level, and 64% contained levels greater than or equal to the DOH 1.5-ppm "no consumption" level (11a). All of these have average levels of mercury above the U.S. EPA health criterion for methylmercury of 0.3 ppm(33). "Coastal residents have higher levels of mercury than people who live inland, and anglers and their families are also at higher risk of mercury exposure,"(5bd).
Fourteen species of Gulf Coast fish with mercury levels sampled at a 2006 fishing rodeo had average mercury concentrations above 0.5 parts per million (ppm), the level at which Florida and Louisiana issue consumption advisories(9b). The species with levels above 0.5 ppm included cobia (ling), Spanish mackerel, blackfin tuna, amberjack, black drum, gag grouper, barracuda, wahoo, bluefish, bonito, king mackerel, gafftopsail catfish, crevalle jack, and ladyfish. Four of these: king mackerel, barracuda, cobia, and bonito; had average mercury levels exceeding 1 ppm, the United States Food and Drug Administration (FDA) action level and the level at which Alabama and Mississippi currently issue advisories for no consumption. Hardtail, grey snapper, red snapper, red grouper, and speckled trout had average mercury levels above 0.3 ppm, ranging up to about 0.8 ppm. However, many popular species are relatively low in mercury. The lowest average mercury levels were observed in vermilion snapper, tripletail (blackfish), flounder, and gray triggerfish.
Statistical analysis of mercury levels sampled in fish from the Indian River Lagoon and Florida Bay by FDEP indicated that location was the most significant factor affecting mercury levels. With the exception of jack crevalle and gafftopsail catfish, mercury in fish from the Indian River averaged less than the Florida Limited Consumption Advisory. Tissue samples from several species of fish caught in eastern Florida Bay contained higher levels of mercury than did samples of those species collected in other areas. A significant portion of the estuarine fish collected in eastern Florida Bay, including spotted seatrout, exceed the 1.0 mg-Hg/Kg US Food and Drug Administration’s “no consumption” health advisory criterion. Mercury levels were elevated in jack crevalle from all areas. The south Florida species that had the highest mercury levels was Jack Crevalle, with an average of 0.73 ppm in the Indian River Lagoon, 1.07 ppm in E Florida Bay, and 0.40 in W Florida Bay. The other species testing above 0.5 ppm on average was Gafftopsail catfish with 0.59 ppm in IR and 0.57 in W Florida Bay, spotted sea trout with 0.44 ppm in IR Lagoon, 0.92 ppm in E Florida Bay, and 0.25 ppm in W Florida Bay, Bluefish with 0.47 ppm in IR Lagoon and 0.68 ppm in W Florida Bay, and snook with 0.4 ppm in IR Lagoon, 0.52 ppm in E Florida Bay, and .42 ppm in W Florida Bay. Species with lower mercury levels in order of mercury level were grey snapper, redfish, sheepshead, and flounder.(3b)
Studies (5,37) have also found that the level in most large predator species on the Gulf Coast is higher than levels found to adversely affect health (25,26) with mercury contamination being pervasive along the whole coastal area, and that people who eat Gulf Coast fish at least once per week usually have dangerous levels of mercury(5a). 29% of a coastal sample from Florida, Alabama, and Mississippi ate fish at least once per week(5a). Over 30% of 100 environmental reporters tested at a conference in Pittsburg had elevated levels of mercury(5c). The study found that the older the reporters, or the more often they ate finned predator fish, the more likely he or she harbored high mercury levels. 21% of women of childbearing age in a large sample taken in a study sponsored by Greenpeace had dangerous levels of mercury(over the EPA reference level), and over 30% of those tested in Florida and 4 other states(5d). Approximately one quarter of New York City women in this age group have a blood mercury level at or above 5 g/L, the New York State reportable level(5e).
Mercury contamination in fish is widespread. Mercury was detected by a U.S.G.S. study in all fish sampled from 291 streams across the U.S. (44). Concentrations in about a quarter of the fish sampled exceeded the criterion for the protection of humans who consume average amounts of fish, established by the U.S. Environmental Protection Agency. Some of the highest levels of mercury in fish are from tea-colored or “blackwater” streams in North and South Carolina, Georgia, Florida, and Louisiana—areas associated with relatively undeveloped forested watersheds containing abundant wetlands compared to the rest of the country. High levels of mercury in fish also were found in relatively undeveloped watersheds in the Northeast and Upper Midwest parts of the United States, in areas with abundant wetlands. Elevated mercury levels in fish also are found in streams of the western U.S. that are affected by mining of mercury or gold.
A 2009 study found that inorganic mercury levels in people have been increasing rapidly in recent years(45). It used data from the U.S. Centers for Disease Control and Prevention’s National Health Nutrition Examination Survey (NHANES) finding that while inorganic mercury was detected in the blood of 2 percent of women aged 18 to 49 in the 1999-2000 NHANES survey, that level rose to 30 percent of women by 2005-2006.
For a study in Sweden, fresh water fish consumers were categorized into 3 groups using the break points of at least once per week, at least once per month, and less than once per month(42). Among the high consumers, median concentrations of mercury were 8.6 microg/L in blood, 2.4 microg/g in hair, and 1.1 microg/g creatinine in urine. The relationship between freshwater fish consumption and mercury was significant in all biological media. The high-consumption group had much higher mercury levels in blood (9-fold), hair (7-fold), and urine (15-fold) than the low-consumption group.
Several studies including a large CDC study have found those with higher levels of mercury have higher rates of neurological problems, cardiovascular problems, infertility, and cancer(25,26,30,21). Men in the highest third of hair mercury content (>2 microg/g) had an adjusted 1.60-fold (95% CI, 1.24 to 2.06) risk of acute coronary event, 1.68-fold (95% CI, 1.15 to 2.44) risk of CVD, 1.56-fold (95% CI, 0.99 to 2.46) risk of CHD, and 1.38-fold (95% CI, 1.15 to 1.66) risk of any death compared with men in the lower two thirds(25). High mercury content in hair also attenuated the protective effects of high-serum docosahexaenoic acid plus docosapentaenoic acid concentration. Another study found infertile couples were significantly more likely to have elevated mercury levels than the infertile couples, which was the case for both men (35 percent versus 15 percent) and women (23 percent versus 4 percent). Furthermore, patients who reported eating high levels of seafood showed a clear trend towards elevated mercury levels(26a,f).
A California health clinic study reports that of a California population that eats at least 2 servings of fish per week, 89% had levels of mercury in the blood exceeding 5 micrograms per liter(ug/L), the level considered the safety limit for mercury by U.S. EPA and the National Academy of Sciences(26a). Over 50% had levels over 10 ug/L and 15% had levels over 20 ug/L. The group had chronic health effects including depression, loss of scalp hair, metallic taste, headaches, arthritic pain in joints, irritability, tremors, and numbness and tingling in hands and feet. She also described cognitive problems such as pronounced memory loss, confusion and difficulties in talking. In some cases, those problems were so severe
they interfered with the ability to earn a living or attend school. In all cases, health effects improved after several months of avoiding eating fish. Some women in the group were found to have transferred excessive mercury to their infants solely through their breast milk. One breast-fed baby had three times the EPA's safe level for mercury by the time he was 4 months old; and another had 4 times the EPA safe level at 19 months. Some of the infants with high mercury levels suffered severe neurological problems such as autism, and improved when treated for mercury toxicity. Mercury accumulates in the major organs that receive large amounts of blood, with cumulative damage and effects that often are not fully recognized until later in life(43,21).
The Mobile Register studies(5) have also found that fish and shellfish that feed near offshore oil and gas platforms have significantly higher levels of mercury than other areas(5) due to mercury used in drilling. Over 200 tons of mercury has been added to the Gulf through drilling over the last 30 years. More fishing occurs near such platforms since shellfish and fish tend to congregate in such areas. Other known major sources of mercury throughout the coastal area are air emissions and sewer outfalls, with some other large local industrial sites such as chlor-alkali plants(16). Accumulation of atmospheric oxidants and mercury can cause high levels of mercury deposition in coastal areas when activated by sunlight, which can result in very high levels of mercury in fish and wild life(32). Bacteria in sediments and fish intestines methylate inorganic mercury to methyl mercury(31).
Studies have found that large pelagic Gulf fish species such as marlins, swordfish, and shark have levels of mercury 20 to 30 times that of most Gulf fish species(37). The U.S. FDA recommends that pregnant women entirely avoid eating shark, swordfish, king mackerel and tilefish(10a), because a significant portion of these types of fish have mercury levels above the FDA action level of 1 ppm. However other studies(25,26) including one by the National Academy of Sciences(14) have found the old FDA action level of 1 ppm is obsolete and not adequate to protect the public, as adverse effects have been found for those eating fish at least once per week at average mercury levels below the FDA warning level of ½ ppm(25). The Health Canada limit for mercury in marine and freshwater fish is 0.5 ppm(12b) and the U.S. EPA reference level for children and pregnant women is 0.3 ppm.
Based on this a coalition of organizations using the name Environmental Working Group(EWG) did a large study to more fully assess mercury exposure effects and safety limits(12). In addition to the FDA limits, EWG advises pregnant women, nursing mothers and all women of childbearing age, should not eat tuna steaks, sea bass, oysters from the Gulf Coast, marlin, halibut, pike, walleye, white croaker, and largemouth bass(12). And that these women should eat no more than one meal per month combined of canned tuna, mahi-mahi, blue mussel, Eastern oyster, cod, pollock, salmon from the Great Lakes, blue crab from the Gulf of Mexico, wild channel catfish and lake whitefish. The EWG analysis was based on 56,000 test results on mercury in fish from 7 different government agencies, and toxicity studies by U.S. CDC and National Academy of Sciences. A large FDA study found that the average level of mercury in white canned tuna is 0.358, high enough to require stringent limits to prevent exceeding EPA’s reference dose(36), since the safe levels are commonly exceeded.
In a 2010 study, 55% of samples from the 3 top brands of tuna sold in
the U.S. had mercury levels higher than the EPA standard of 0.5 parts per
million and 5% had levels over the FDA 1.0 ppm limit for commercially sold
However EWG recognizes that fish is an important health food with nutrients and essential fatty acids hard to substitute from other sources. The following fish are safer choices for avoiding mercury exposure: farmed trout or catfish, shrimp, fish sticks, wild Pacific salmon, croaker, haddock, some varieties of flounder, and blue crab from the mid-Atlantic. (12)
Studies have found that total mercury in maternal hair is highly
correlated with methyl mercury in cord blood of the fetus. Both hair T-Hg and cord blood methylmercury(MeHg) increased with increasing consumption of seafood or number of dental fillings(38,39,21), but hair mercury is primarily methylmercury and not highly correlated with number of dental fillings. Inorganic mercury(I-Hg) in cord blood increases significantly with increasing number of maternal dental amalgam fillings(38,39,21). Since dental amalgam is the largest source of mercury exposure in most people who have several amalgams and other forms of mercury are methylated by mouth bacteria and bacteria, yeasts, etc. in the intestines; dental amalgam has been found to be a large source of methyl mercury in some people. Nutritional factors have been found to partially offset the neurotoxic effects of mercury(21). Selenium is commonly found in many species of fish and partially protects from mercury and methyl mercury neurotoxicity by preventing damage from free radicals or by forming inactive selenium mercury complexes(40,41).
Studies have found that freshwater predator fish such as bass, pickerel, and bowfin have high levels of mercury in most of Florida, with fish consumption warnings issued(3,4,20). Eight other species (alligator gar, black crappie, white crappie, blue catfish, flathead catfish, brook trout, drum, striped bass) have average test levels near the FDA warning level or some tested above the FDA action level(4). Studies have found that predator species such as wading birds, alligators, and Florida Panthers whose diet depends on fish have high levels of mercury, and adverse health and reproductive effects(7). In recent U.S. EPA tests of fish caught in Florida lakes, every fish sample tested was contaminated with mercury, and sixty-three percent contained mercury levels that exceed EPA’s “safe” limit for women of childbearing age(11b). Nationally, 55 percent of the fish samples exceeded EPA’s safe mercury limit for women of childbearing age. Over 2 million acres of Florida’s surface waters have fish with high levels of mercury, averaging above the FDA/EPA warning level of 0.5 parts per million(20). The major source of mercury into these water bodies is air deposition that is brought down in rain. A Florida emissions inventory found that the major sources of atmospheric mercury were municipal solid waste combustors (MSW), electric utility industry, and medical waste incinerators(20), but incinerator emissions have been reduced in recent years.
The most vulnerable groups to mercury exposure are women who are pregnant or might become pregnant, nursing mothers, and young children(8,10b,12,27,28). These groups should limit consumption of freshwater fish to no more than one meal per week (6 ounces of cooked fish for adults and 2 ounces of cooked fish for young children).
High levels of mercury including the very toxic organic forms are being measured in rainfall throughout the U.S.(24) High levels of the extremely toxic di-methyl and methyl mercury forms of mercury are being found in landfill gas coming from landfills and appear to be a source of some of this(22-24). Bacteria in landfills and in soils where sewer sludge is spread have been found to be methylating elemental and inorganic mercury to the organic forms(22,23). Government studies have found that all sewers in the U.S. and all sewer sludge have high levels of mercury, with the most common significant source dental amalgam from dental offices or from being excreted mercury into sewers from those with amalgam dental fillings(13,23,28,21). Dental amalgam waste and mercury from sewer sludge are major sources of mercury in some landfills and sludge is also used in landspreading on farms and other areas. Programs are already being implemented to reduce most other sources of mercury into sewers and into landfills such as flourescent light tubes. High levels of mercury have been found to be taken up in crops on land where sludge is spread(23), and high levels of emissions of elemental and organic mercury forms methylated by soil bacteria. Health Canada and Canadian sewer agencies have also documented similar information on mercury emissions from amalgam waste and sewer sludge to waterways, crops, and air(29), and have implemented standards and restrictions to help alleviate this problem.
Recent government studies have documented that the environmental effects of mercury excreted into sewers from those with amalgam dental fillings are widespread and significant, and are affecting everyone in Florida(22-24,29). Dental amalgam mercury has been documented to have a high bioavailability in water(31) and dental offices are a major source of mercury into waterways. Also 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. 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 in Florida have such health warnings[3,4] banning or limiting eating of fish, and most other states and 4 Canadian provinces have similar health warnings(6,29). Wisconsin has fish consumption warnings for over 250 lakes and rivers(6,13) and Minnesota even more, as part of the total of over 95,000 such lakes with warnings(6), 33% of all U.S. lake surface area and 15% of all U.S. river miles. All Great Lakes as well as many coastal bays and estuaries and large numbers of salt water fish carry similar health warnings-70% of all coastal miles and 100% for the Gulf of Mexico.
Government studies have determined that dental amalgam is by far the largest source of mercury in sewers and sewer sludge, with dental amalgam the largest source and waste excretion from those with amalgam the second largest source(13e). Unlike many European countries and Canada(29) which have more stringent regulation of mercury that require 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 per dentist without amalgam separators is approximately 270 milligrams per day(18,13e(Table4)). For the U.S. this would be approximately 5400 kg/yr (or slightly over 6 tons/year of mercury into sewers and thus into streams and lakes in most cases. In Canada the annual amount discharged is about 2 tons per year, with portions ending up in waters/fish, some in landfills and cropland, and in air emissions. The recently enacted regulations on dental office waste are expected to reduce emissions by at least 63% by 2005, compared to year 2000 levels(29).
A study in Michigan estimated that dental mercury is responsible for approximately 14 % of mercury discharged to streams(18). Other EPA and municipal studies(18,13) found that dental office waste was responsible for similar levels of mercury in lakes, bays, and streams in other areas throughout the U.S. Another Canadian study found similar levels of mercury contribution from dental offices into lakes and streams(29). Surveys of dental office disposal practices found the majority violated disposal regulations, and dangerous levels of mercury are accumulating in pipes and septic tanks from many offices(18,29). As previously noted, dental amalgam mercury has been documented to have a high bioavailability in water(31).
The total discharge into sewers from dental amalgam at individual homes and businesses is second only to dental offices, since the average person with several amalgam fillings excretes in body waste as much as 100 micrograms per day of mercury and (17,19,21). This has also been confirmed by medical labs(13c) such as Doctors Data Lab in Chicago and Biospectron in Sweden which do thousands of stool tests per year and is consistent with studies measuring levels in residential sewers by municipalities(13b). The reference average level of mercury in feces(dry weight) for those tested at Doctors Data Lab with amalgam fillings is 0.26 milligrams/kilogram, compared to the reference average level for those without amalgam fillings of .02 mg/kg(ppm). The AMSA study adopted a more conservative estimate of 27 to 39 micrograms per day(13e). In the U.S. this would amount to between 2500 to 7300 kilograms per year into sewers or from 3 to 8 tons per year. 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.
Oak Ridge National Laboratory (ORNL) studies have also documented high levels of mercury in sewers and sewer sludge(23). 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(13). Over 3 tons of mercury flows into the Chesapeake Bay annually from sewer plants, with numerous resulting fish consumption advisories for that area and similar for other areas(6). The EPA discharge rule is being reevaluated 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(14).
However it should be remembered that the largest sources of mercury air emissions are coal power plants and incinerators, with additional significant contributions from power plants burning bunker oil, and these are also significant sources of mercury in Florida's streams, lakes, and bays(16). Florida ranks 14th nationwide for the most mercury emissions from power plants, releasing 2,411 pounds of mercury into the air in 2002, according to the most recent EPA data(11b). The Crystal River Energy Complex alone emitted 491 pounds of mercury into the air in 2002. Since only ½ gram of mercury is required to contaminate all fish in a 10 acre lake to dangerous levels requiring health warnings(2), all of these sources need to be reduced to result in fish safe to eat.
Thousands of peer-reviewed studies have documented that amalgam dental fillings, in addition to being a major source of mercury in the environment and fish, are also the number one source of mercury in most people with several fillings, with exposure levels above Government health guidelines (21). The Gov't health guideline(MRLs) for mercury(15) of 0.2 micrograms per kilogram body weight per day for organic mercury result in limits of approx. 6 micrograms per day for a 44 pound child, 16 ug/d for a 115 pound adult, and 24 ug/day for a large adult. The corresponding MRL for mercury vapor(the type emitted by amalgam) is 0.2 micrograms per cubic meter of air breathed which results in a limit of about 6 ug/d for a large adult and less for a child. These levels are commonly exceeded in people with several amalgam fillings(21) and in those who regularly eat seafood with mercury levels commonly found in Florida fish (4, 5,12,etc. ). Thousands of peer-reviewed studies also document that mercury causes over 30 chronic neurological or immune related health conditions(21,27,28), from which thousands are documented to have recovered or significantly improved after proper treatment of mercury toxicity(21b, Section VI, 20). Those interested in additional information on testing for or treatments for mercury toxicity or in clinics with experience treating mercury toxicity problems can contact the Florida Chapter of the national patients support organization(DAMS) at: www.flcv.com/indexd.html
(1) ATSDR/EPA Priority List for 2005: Top 20 Hazardous Substances, Agency for Toxic Substances and Disease Registry,U.S. Department of Health and Human Services, www.atsdr.cdc.gov/clist.html; & (b) Agency for Toxic Substances and Disease Registry, U.S. Public Health Service, Toxicological Profile for Mercury , 1999, &(c) U.S. EPA, Region I, 2001, www.epa.gov/region01/children/outdoors.htm
(2) Electric Power Research Institute. Mercury in the Environment. Electric EPRI Journal 1990; April, p5; & EPRI Technical Brief:"Mercury in the Environment", 1993
Florida Department of Health, Bureau of Environmental Toxicology, Health Advisories for Mercury in Florida Fish 2009, http://www.doh.state.fl.us/floridafishadvice/Final%202009%20Fish%20Brochure.pdf ;
& FDEP, Toxic metal levels in Florida shellfish, 1990; & Mercury Studies in the Florida Everglades, http://sflwww.er.usgs.gov/publications/fs/166-96/
(b) & A Comparison of Mercury in Estuarine Fish: Florida Bay and Indian River Lagoon, www.dep.state.fl.us/southeast/ecosum/ecosums/mercury.pdf
(4) U.S. Geological Survey, The Occurrence of Mercury in the Fishery Resources of the Gulf of Mexico; http://mo.cr.usgs.gov/gmp/hg.cfm &, Estuarine Research Federation
& (b)SFWMD, 2003 Everglades Consolidated Report, Appendix 2B-4: Preliminary Report on Florida Bay Mercury
and © Florida DOH Mercury Saltwater Fish Advisories, 2004
& D.H.Adams, R.H.McMichael, Florida Marine Research Institute, Technical Reports, Mercury Levels in Marine and Estuarine Fishes of Florida, 2001; & Mercury in Marine Fish, Florida Fish & Wildlife Conservation Commission, http://capmel.com/Mercury_in_fish.htm
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