THE CASE AGAINST MERCURY IN DENTAL AMALGAM

Transcription

1 THE CASE AGAINST MERCURY IN DENTAL AMALGAM Dental amalgam should have no role in modern dentistry. It is a 200 year old technology containing 50% mercury, which exposes a significant part of the community to a very toxic material inside their bodies. Cost-effective substitutes of comparable longevity and effectiveness have been available for over 20 years. The NHMRC view The NHMRC (National Health and Medical Research Council) in 1998 recommended against the use of mercury dental amalgams in children and pregnant women. The NHMRC Working Party report states:...general public and environmental health principles dictate that where possible exposure to mercury from dental amalgams be reduced where a safe and practical alternative exists. This becomes more prudent in special populations, including children, women in pregnancy and persons with existing kidney disease. Since 2002, the Australia Federal Government has circulated brochures suggesting to parents, young women, and those with kidney problems that they look at alternatives for their children and themselves. In spite of this recommendation, almost a decade later, mercury amalgam is still used for 30% of fillings. The view of dentists Unfortunately the Australian Dental Association has resisted any phase-out of mercury amalgams and as recently as November 2010 has adopted a policy on Safety of dental amalgam which fails to even repeat the advice of the NHMRC. 0safety%20of%20dental%20amalgam.pdf To their credit, half of Australia s dentists have stopped using amalgam, and the proportion of fillings undertaken using mercury amalgam has fallen from 68% in 1983 to 30% by the end of the 1990 s. (NHMRC 1999). If the public were fully informed of the composition of mercury amalgam fillings and dentists were aware of the negative environmental impact and health hazards of this material, then this proportion would drop even further. Despite younger dentists tending to move away from the use of mercury amalgams, the profession as a whole has been resistant to adopting cost-effective alternative materials. AUSTRALIANS FOR MERCURY FREE DENTISTRY INC. The Australian Chapter of the World Alliance for Mercury Free Dentistry 131 Commercial Road, South Yarra, Victoria 3141, Australia Telephone: Fax: Internet: info@mercuryfreedentistry.com.au

2 All dentists must be competent in placement of non-amalgam alternatives prior to graduation and the development of these mercury free materials already offer comparable bonding to dental tissue but with the advantage that they do no cause stress fractures of cusps of teeth in distinct contrast to the metallic mercury dental amalgam fillings. More natural tooth structure is preserved by adopting adhesive bonded restorations than relying on mechanical undercuts to retain metallic mercury amalgam fillings. Most patients are receiving misinformation about the composition of the filling material being used. The majority of dentists refer to mercury amalgam fillings as silver fillings, inferring that this material has a precious value and the patients are not being informed these fillings contain up to 50% liquid mercury. The Australian Dental Association does not accept there is a health problem with amalgam fillings citing the World Health Organization. However, a 2003 WHO report confirmed that mercury contained in dental amalgam is the greatest source of mercury vapour in non-industrialized settings, exposing the concerned population to mercury levels significantly exceeding those set for food and for air. (Source: Another WHO report from 2005 Mercury Usage in Health Care acknowledges the serious negative environmental impact of mercury emissions from dental amalgam into the air and discharges via sewers into waterways and land. WHO argues by choosing mercury-free alternatives, a health-care institution can make a tremendous impact in reducing the potential for mercury exposure to patients, staff and the environment. The UNEP Governing Council has gone further in concluding:...[there is now] sufficient evidence of significant global adverse impacts from mercury to warrant further international action to reduce the risks to humans and wildlife from the release of mercury to the environment. The UNEP Governing Council decided that national, regional and global actions should be initiated as soon as possible and urged all countries to adopt goals and take actions, as appropriate, to identify populations at risk and to reduce human-generated releases. The ADA does however concede that mercury amalgam fillings are becoming unpopular and that strong tooth-coloured fillings have been developed in recent years for use on the back teeth without discernable problems. The ADA also accepts that the general principles of public health during pregnancy mean it is prudent to avoid any dental treatment that can be deferred. This includes the removal or placement of amalgam fillings during the pregnancy or breastfeeding. Public dentistry Neither are the recommendations of the NHMRC being upheld within public dental clinics. The current practice within government funded public dental clinics is to use mercury dental amalgam fillings to restore decayed permanent teeth regardless of whether the patient is a pre-schooler or pregnant.

3 This also applies to clinics that deliver dental services to Indigenous people and those serving in the Armed Forces. The Government should start the phase out within the public dentistry sector. Furthermore, lack of Government funding has meant public dental clinics have been slow to adopt the mandatory introduction of amalgam separators to protect the environment from hazardous mercury dental amalgam waste. The international moves to phase out amalgam An important UN Global Treaty on Mercury is being negotiated through the United Nations Environmental Program (UNEP) to control the world wide use of mercury on the basis of its high risk to human health and the environment. The draft Treaty addresses mining, waste, industrial use and illegal trade in mercury. Importantly it proposes a phase-out of five products containing mercury including dental mercury amalgams. The Treaty negotiating process is half completed and a final document is expected by The third session (of five) of the Intergovernmental Negotiating Committee to prepare a global legally binding instrument on Mercury (INC3) will be held in Nairobi, from 31 October to 4 November Several countries have already enacted bans on mercury amalgams without great difficulty. As UNEP itself noted in a 2006 report: Among others, Sweden, Japan, Denmark and Finland have implemented measures to greatly reduce the use of dental amalgams containing mercury. In many countries, dental practitioners have been relatively slow to change longstanding methods of treatment, many of them perhaps not convinced of compelling reasons to do so. Most recently, the Parliamentary Assembly of the Council of Europe adopted a resolution on 27 May 2011 urging its 47 member countries to start restricting or prohibiting the use of amalgams as dental fillings for two major reasons: Health:...amalgams are the prime source of exposure to mercury for developed countries, also affecting embryos, foetuses (through the placenta) and children (through breastfeeding). Exposure to mercury can seriously affect the health of patients and dental professionals... Environment:...between 60 and 90 tonnes of mercury from dental surgeries are released into and contaminate Europe s atmosphere, surface waters and soil every year. This resolution is a significant development in the lead up to the next round of UNEP negotiations. The Council of Europe joins the growing international call for the amalgam phase-out that is already endorsed by the African region, the Arab League, and the United States.

4 The draft Australian Objection Unfortunately, the Australian Government has foreshadowed it will lodge an objection to the phase out of dental amalgam in the following terms: Australia has concerns with the imposition of immediate or short-term restrictions on the use of dental amalgam. Whilst Australia acknowledges the desirability of phasing out the use of dental amalgam over time, Australia would point to the public health advantages of dental amalgam. These are: lower cost, lesser complexity in use than alternative filling materials and the creation of a better seal in teeth with dental amalgam over alternative filling materials. Australia s view is that the Conference of the Parties to the mercury treaty can, in time, return to the question of the inclusion of dental amalgam in Annex C. This will allow the continued development of composite alternatives to the point where they can properly replace all dental amalgam use. (In the Treaty language, the issue is the inclusion of dental amalgam as one of five products to be listed in Annex C, which countries commit to phasing out). There is no evidence for the claimed public health benefits. The cost of equipping a dental surgery to protect occupational health and recover waste amalgam wipes out the initial cost margin, increases the complexity of safely using this product and effective alternatives are now well established and successfully used in preference by many dentists. The actual cost of the filling material whether it is amalgam or an alternative is less than 5% of the expense of providing the dental service and therefore the relative cost is not a critical factor. The Health Risks of Mercury Amalgams Mercury is bio-accumulative and is a well known health risk to children, foetuses (as it crosses the placental barrier) and those with impaired kidney function. This view was adopted by the NHMRC more than a decade ago and since then the US Food and Drug Administration, amongst others, has confirmed that there is no evidence amalgam is safe for children under the age of six. Health Canada has directed that mercury dental amalgams be banned in treating women and children and it has also been totally banned in Sweden. Other European countries such as Denmark, Norway and Italy are taking steps to phase-out or regulate mercury dental amalgam due to the health risks it poses. The health risks of mercury dental amalgams to dental patients arise during its initial placement, exposure during subsequent treatment or removal of fillings, and long term exposure through trace amounts of vapour released from chewing food, accelerated vapourisation from consuming hot beverages, irradiation of the head and neck area during X rays etc, and absorption via the placenta to the unborn infant and via breast milk to the suckling baby.

5 Mercury dental amalgam is also a work place hazard exposing dental workers - who are primarily women of reproductive age to mercury vapours with little or no precautions in place to protect themselves. Throughout the manufacturing and use of amalgam, all workers are exposed to this great health risk. This includes those who mine the cinnabar, those working in smelters, packaging and handling the metal, manufacturing the encapsulated amalgam, the dentists, dental nurses and dental reception staff, all the way through to the technicians, launderers, plumbers and sewage workers exposed to the amalgam wastes. Mercury release from a single surface dental amalgam has been measured at micrograms per day. According to WHO (2005),...around 80% of the inhaled mercury vapour is absorbed in the blood through the lungs. It may cause harmful effects to the nervous, digestive, respiratory, immune systems and to the kidneys, besides causing lung damage. Adverse health effects from mercury exposure can be: tremors, impaired vision and hearing, paralysis, insomnia, emotional instability, developmental deficits during foetal development, and attention deficit and developmental delays during childhood. Recent studies suggest that mercury may have no threshold below which some adverse effects do not occur. The mercury vapour easily penetrates the blood-brain barrier and is a well documented neurotoxin. Neurological and behavioural disorders in humans have been observed following inhalation of elemental mercury vapour (UNEP 2002) The range of exposure from dental amalgam may vary greatly among individuals. There is a body of research that has concluded that the average exposure from dental amalgam is below the level at which there are health effects. However, other research has indicated that a significant subset of the population may be vulnerable to mercury exposure at these same levels. (Echeverria et al, 2006 FDA) Recent topics of research include the prevalence of the APOE genotype and the incidence of Alzheimer s Disease. Some of the evidence for direct exposures is disputed because of the difficulty of measuring such trace amounts and the problem of isolating their impact on brain toxicity in a real life setting where many factors are at play. However the precautionary principle should be given considerable weight in this situation because the toxicity of mercury is extremely well established. Dental use is the only application where there is such close contact with mercury for the general population literally implanted into their bodies.

6 Trade in dental amalgam Dental use of mercury represents tonnes a year or about 10% of the world demand. World demand has diminished by two thirds since the 1970 s falling from 9000 tonnes to tonnes. (UNEP 2006) The 2006 UNEP Summary of Supply, Trade and Demand Information on Mercury summarised the global situation on the use of amalgams as follows: In many higher income countries, dental use of mercury is now declining. The main alternatives are composites (most common), glass ionomers and compomers (modified composites). However, the speed of decline varies widely, so that mercury use is still significant in most countries, whilst in some countries it has almost ceased. Australia is not a significant producer of mercury, importing most mercury from Europe. There is a growing mercury recycling activity in Australia collecting mercury from recycled fluorescent tubes and dental amalgam. Australia s consumption represents less than 1% of world mercury use our gold mining industry does not use mercury in contrast to the widespread and illegal use of mercury in small scale gold mining in Africa and Latin America. However, Australia is a major manufacturer of dental amalgams through Southern Dental Industries a Melbourne firm, now exporting to many overseas countries and possibly representing the source of a third of the world s traded mercury dental amalgams. This is a significant problem for two reasons: Firstly, it is entrenching a bad technology in those countries where changing diets are increasing consumption of sugar. Consequently there is greater use of western dental methods for treating dental decay at a time when the old technology of placement of mercury dental amalgams should be phased out. Secondly, there are great concerns that a lot of the mercury amalgam being exported from Australia is in fact being misdirected into the illegal small scale gold mining activities in Africa and Latin America and consequently causes serious pollution. At the very least, export controls should be imposed to ensure Australian mercury dental amalgam cannot be diverted in this way. The difficulty in preventing diversion of imported mercury dental amalgam to gold mining is one reason African nations are calling on the developed countries to phase-out mercury dental amalgam.

7 The Environmental Problems with Mercury Dental Amalgams The use of mercury dental amalgam is a major environmental problem due to releases of waste from dental surgeries and mercury vapour from human. UNEP reports an estimate that in the USA, mercury from dental amalgams typically contributes 50% of mercury load to wastewater. Extracted teeth are required to be treated as hazardous waste and disposed of through mercury recyclers. Another source of mercury of dental origin comes from amalgam bearers dental patients who have these mercury fillings implanted. This group have detectable levels of mercury found in their bodily fluids including saliva, urine, faeces which enter the sewers. Dental amalgams are also a source of mercury contamination of breast milk and absorption through the placental barrier. Technology is available to catch up to 99% of mercury amalgam waste from dental surgeries reaching the waterways. However the vast majority of private dentists and even Government dental clinics have not had amalgam separators installed. Dental mercury when it enters into the environment is metabolized by algae into the virulent neurotoxin methyl mercury which bio-accumulates in the aquatic food chain and was infamously responsible for the Minamata tragedy. There also exists the threat of wider environmental contamination from the mercury dental amalgam manufacturer s plant site and escape of elemental mercury or dental amalgam during road or sea transport.