..........Anbei sende ich Ihnen ein Editorial des Journal of Dental Research mit einer
aktuellen Stellungnahme zu Amalgam aus dem Jahr 2008.
Das ist die neueste Stellungnahme der höchsten wissenschaftlichen
Vereinigung der Zahnmedizin (Association of Dental Research). Dieser
schließe ich mich an.
Has Dental Amalgam Been Torpedoed and Sunk?
Derek W. Jones
Professor Emeritus of Biomaterials, Dalhousie University, Halifax, NS,
Canada
[email protected]
KEY WORDS: Mercury • amalgam • environment • scientific principles
For the past 20 years, the public has been bombarded by sensational,
confusing, and misleading media reports about health issues related to
dental amalgam. The public opinion on this issue has been modified by
minority, non-scientific views driven and supported by media sensationalism.
Mobilization of irrational public fear is the strategy used by lobby groups
to pressure governments to change public policy (Jones, 1993). It is
important that governments adhere to scientific principles and base health
and environmental policies on sound scientific knowledge. Dentistry is an
applied science and needs to bring issues such as those dealing with dental
amalgam to the attention of governments.
I recently read a news item regarding the ban being imposed on dental
amalgam in Norway. As a scientist, I was appalled to read of the decision
taken by the Norwegian Government (Ministry of Environment) on December 14,
2007. This legislation aims to prohibit the production, importation,
exportation, sale, and use of substances that contain mercury. However, the
prohibition does not cover mercury that occurs naturally in coal, ore, and
ore concentrations (presumably cinnabar could be included in this category).
According to the Norwegian government, the regulation covering dental
amalgam will come into effect on January 1, 2008, and for more limited use
on December 31, 2010 (Norwegian Ministry of the Environment, 2008). In a
prepared statement, Norwegian Minister of the Environment Erik Solheim said
that the reason for the ban is the risk to the environment that mercury may
pose. "Mercury is among the most dangerous environmental toxins.
Satisfactory alternatives to mercury in products are available, and it is
therefore fitting to introduce a ban," said Solheim.
My strong objection to this bureaucratic travesty relates to the following:
At least 50% of environmental mercury pollution comes from natural sources.
Some 42% of environmental mercury pollution comes from the burning of fossil
fuels (and yet for the moment they exclude coal) (Jones, 2004).
No valid scientific studies have ever shown that dental amalgam poses a
health hazard to patients, to dentists, or to the environment.
A patient with 10 amalgam surfaces in his/her mouth would have a mercury
intake into the blood which would be only 2% of the World Health
Organization’s Acceptable Daily Intake (WHO ADI 40 µg/day) for mercury, with
no adverse health effects.
I have calculated that the environmental impact of mercury from 800,000
dental offices worldwide would represent between 0.04 and 0.2% of the total
worldwide environmental mercury pollution from all sources (this would be
significantly reduced by the use of amalgam traps [ISO 11143, 1999], which
are increasingly being used).
I have also calculated that the worldwide environmental impact of mercury
discharges into the sewers from 20 billion amalgam surfaces in people’s
mouths represents between 0.01 and 0.07% of the total environmental mercury
pollution.
I could understand if all industrial use of mercury, such as the burning of
fossil fuels, was banned in Norway, together with the unsafe disposal of
mercury-containing batteries and lamps. Each year, close to 8000 kg of
mercury from fluorescent lamps end up in landfills and incinerator plants in
North America alone (Chong, 1997). Without question, it is the emerging
industrial countries that represent the major threat to increased mercury
pollution. Estimates of mercury put into sewer systems by dentistry are
incredibly small in comparison with the worldwide release of mercury, which
has been estimated as 6.3 million kg (Chong, 1997). However, another
estimate puts the global figure at between 22 and 33 million kg of mercury
discharged into the environment each year as a result of human activities
(Chin et al., 2000). Whatever the real number is for total mercury released
into the environment on a global scale, the amount released from dental
procedures and dental amalgam is not a significant contributor to the
problem.
The proposed implementation by Norway to ban a very sound and effective
dental material makes no scientific, economic, or environmental sense at
all. Unlike composite-resin-based materials (alternatives to amalgam
fillings), amalgam has an elastic modulus (stiffness) similar to that of
natural tooth enamel. This lends support to the tooth structure by the
filling material. Composite resin fillings, in contrast, are less stiff than
natural tooth enamel and are unable to support the tooth structure at the
margins to the same extent. Unlike amalgam, composite resin materials take
up water, which is detrimental to their mechanical properties. Amalgam has
wear characteristics similar to those of natural teeth, while composite
materials wear more readily. In addition, interproximal placement of amalgam
is much easier than for composite. Composite resin materials retain a
greater amount of plaque compared with amalgam, which can predispose to
dental caries adjacent to the composite restorations. Composite resin
materials are required to be replaced more frequently than dental amalgam.
Each time a restoration has to be replaced, additional natural tooth
structure is lost.
At present, there is no conclusive evidence in the scientific literature to
demonstrate a link between the cause of irreversible neurological disorders
or of impaired kidney function and mercury vapors from dental amalgam.
Animal experiments to date have not been able to establish conclusively any
cause-and-effect link that can be extrapolated to human exposure to mercury
from amalgam restorations (Jones, 1999).
Although it is generally accepted that some 50% of mercury pollution comes
from natural sources, the relative contribution from natural vs.
anthropogenic mercury sources remains unclear, and the natural source may be
considerably higher. Pollution from dentistry is insignificant compared with
that from industrial use and natural sources. Clearly, the above information
leads to the logical conclusion that banning "dental amalgam" is a political
issue that will have no impact on total worldwide mercury pollution.
A colleague (C Lloyd, personal communication) recently brought to my
attention the very significant mercury pollution problem faced by the
Norwegian government. This involves a German submarine U864 that was
torpedoed off Bergen in February, 1945. It was carrying some 65 thousand kg
of mercury and heading for Japan (Oziewicz, 2006; Cowell and Gibbs, 2007).
The wreck was discovered in 2003, and the Norwegian government has been
criticized for mishandling this mercury pollution problem. It is tempting to
consider whether the banning of dental amalgam by Norway is in fact a
political diversion.
FOOTNOTES
About the author: Derek Jones is a Past President, Canadian Association for
Dental Research (CADR, 1992-95), Past President of the IADR Dental Materials
Group (1990-91), and Chair of the Canadian Dental Association’s Dental
Materials and Devices Committee (1993-1998). He is currently Chair of ISO/TC
106 Dentistry (2005-2010). He was Secretary of ISO/TC/SC1 Dental Filling and
Restorative Materials from 1979 to 1997, and Chair of ISO/TC/SC1 from
1998-2005, as well as Chair, Canadian Standards Association Technical
Committee on Dentistry, and Chair, Canadian Advisory Committee to the
International Standards Organization, 1979-2005.
Received January 10, 2008; Accepted January 10, 2008
REFERENCES
Chin G, Chong J, Kluczewska A, Lau A, Gorjy S, Tennent M (2000). The
environmental effects of dental amalgam. Aust Dent J
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Chong R (1997). Mercury reduction and product stewardship. Paper presented
at Mercury Elimination and Reduction Symposium Pollution Probe, May 5–6,
1997, Toronto.
Cowell A, Gibbs W (2007). German sub menaces North Sea 61 years after
sinking, International Herald Tribune Europe, January 10.
ISO 11143 (1999). Dental equipment-amalgam separators. Geneva, Switzerland:
ISO Central Secretariat.
Jones DW (1993). The enigma of amalgam in dentistry. J Can Dent Assoc
59:155–166.[Medline]
Jones DW (1999). Exposure or absorption and the crucial question of limits
for mercury. J Can Dent Assoc 65:788–792.
Jones DW (2004). Putting dental mercury pollution into perspective. Br Dent
J 197:175–177.[ISI][Medline]
Norwegian Ministry of the Environment: Amendment of regulations of 1 June
2004 #922 relating to restrictions on the use of chemicals and other
products hazardous to health and the environment (product regulations). The
amendment will come into effect 1 January 2008. WHO (2004). International
Digest of Health Legislation. Reg 1479 amending Reg 922, 17 Nov 2004, and
Reg 818 amending Reg 922, 11 July 2005.
Oziewicz E (2006). Toxic shield guards U-864’s secrets. The Globe and Mail,
December 7.
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