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.[1]  The extreme toxicity of mercury can be seen from documented effects on wildlife by very low levels of mercury exposure. 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[2].  Over half the rivers and lakes in Florida have such health warnings[3] banning or limiting eating of fish, and most other states and 4 Canadian provinces of Canada have similar health warnings regarding the eating of fish.  Wisconsin has fish consumption warnings for over 250 lakes and rivers(13). Coastal bays and estuaries and large numbers of salt water fish carry similar health warnings.

Unlike many European countries with 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(4).  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.  A study in Michigan estimated that dental mercury is responsible for approximately 14 % of mercury discharged to streams(5). An EPA study(13) found that dental office waste were 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 dangerous levels of mercury are accumulating in pipes and septic tanks from many offices(14).

The discharge into sewers from dental amalgam at individual homes and businesses is even more than at dental offices, since the average person with amalgam fillings excretes in body waste over 100 micrograms per day of mercury(6,7,8).  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.  In the U.S. this would amount to approximately 7300 kilograms per year into sewers or over 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.   According to an EPA study the majority of U.S. sewerage plants cannot meet the new EPA rule for mercury discharge into waterways due to household sewer mercury levels(15). 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.   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.

     Additionally cremation of those with amalgam fillings adds to air emissions and deposition.   The discharge into sewers from dental amalgam at individual homes and businesses is even more than at dental offices, since the average person with amalgam fillings excretes in body waste over 100 micrograms per day of mercury(6,7,8).  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.  In the U.S. this would amount to approximately 7300 kilograms per year into sewers or over 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.   According to an EPA study the majority of U.S. sewerage plants cannot meet the new EPA rule for mercury discharge into waterways due to household sewer mercury levels(15). 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.   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.

     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 site air mercury standards(9), 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 5 ten acre lakes to the extent there
would be dangerous levels in fish(2).  A Japanese study estimated mercury emissions from a small crematorium there as 26 grams per day(10).  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%(11). A study of assessing hair mercury in a group of staff at some of the 238 British crematoriums found that the groups hair mercury were significantly greater than that of controls(12).

                                                     References
(1)  U.S. Environmental Protection Agency (EPA), 1996, "Integrated Risk Information System,  National Center for Environmental Assessment, Cincinnati, Ohio(& web page); &  ATSDR/EPA Priority List for 1999: Top 20 Hazardous Substances, Agency for Toxic Substances and Disease Registry, U.S. Department of Health and Human Services,    http://www.atsdr.cdc.gov/99list.html
(2) Electric Power Research Institute.   Mercury in the Environment. Electric EPRI Journal 1990; April, p5.
(3) Florida Department of Health, Bureau of Environmental Toxicology, Health Advisories for Mercury in Florida Fish  1997;  10-15.
(4)Arenholt-Bindslev, D.; Larsen, A.H. "Mercury Levels and Discharge in Waste Water from Dental Clinics" Water  Air Soil Pollution, 86(1-4):93-9, (1996).
(5)Rowe NH; Sidhu KS; Chadzynski L; Babcock RF. School of Dentistry,
University of Michigan, Ann Arbor,  USA.  J Mich Dent Assoc 1996
Feb;78(2):32-6
(6)Skare I; Engqvist A.  National Istitute of Occupational Health, Human
exposure to mercury and silver  released from dental amalgam
restorations.  Arch Environ Health 1994 Sep-Oct;49(5):384-9.
(7)Bjorkman L; Sandborgh-Englund G; Ekstrand J.  Mercury in saliva and
feces after removal of amalgam  fillings. Toxicol Appl Pharmacol 1997
May;144(1):156-62
(8) Ekstrand J; Bjorkman L; Edlund C; Sandborgh-Englund G.
Toxicological aspects on the release and  systemic uptake of mercury
from dental amalgam.  Eur J Oral Sci 1998 Apr;106(2 Pt 2):678-86
(9) Rivola J, Krejci I, Imfeld T, Lutz F.  Cremation and the environmental mercury burden.  Schweiz Monatsschr Zahnmed 1990;100(11):1299-303; &  Matter-Grutter C, Baillod R, Imfeld T, Lutz  F. Mercury emission measurements in a crematorium. The dentistry aspects.  Schweiz Monatsschr   Zahnmed 1995;105(8):1023-8
(10) Yoshida M; Kishimoto T; Yamamura Y; Tabuse M; Akama Y; Satoh H.
 Amount of mercury from dental amalgam filling released into the atmosphere by cremation.
 Nippon Koshu Eisei Zasshi 1994 Jul;41(7):618-24.
(11) Reese Km.  Mercury emissions from crematoria.  Chem & Engin News,
 12-7-98, p80-81; &  Lancet 1998; 352, 1602.
(12) Maloney S. et al, Nene Univ. College, Northhampton,   Crematoria
staff face risk from  mercury in tooth  fillings.  Brit Med Journal,
2000; & V. Mc Donald, health Corresponsdent, Daily Telegraph.
(13) U.S. Environmental Protection Agency Mercury Sourcebook: a Guide to
Help Your Community Identify and  Reduce Releases of Elemental Mercury.
Section III, Mercury Use: Dentists, p249-292.
 Http://www.epa.gov/grtlakes/bnsdocs/hgsbook/index.html
(14) International DAMS Newsletter, Volume XIII, Spring/Summer 2000,
(15) Household mercury complicates EPA Rule, A. Huslin, Washington Post,
Aug 26,2000, pg B2.