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Introduction and Discussion

 

(Forming part of the ASOMAT submission to NHMRC June 1998)

ASOMAT was formed in order to create awareness of research, hitherto ignored, which supports the view that amalgams are not harmless. This was done out of necessity because of the regrettable one sided portrayal and widespread misrepresentation of this issue by the dental associations.

There have been a number of reviews in the past few years. None of these reviews have confirmed the safety of amalgams, merely that there is insufficient evidence of harm. In its assessments of these reviews, a number of which are critical of Richardson’s Risk Assessment Study, the Working Party needs to be aware of the intensely political nature of this controversy. It is noteworthy that Richardson’s study is the only serious risk assessment study performed on dental amalgams using standard and accepted risk assessment methodology. It was extensively peer reviewed by others expert in this field and was done by an investigator with no vested interest in the outcome. Based on the published data which he examined and which was deemed to be appropriate by the peer reviewers, he showed that the number of amalgams which could be placed without exceeding the calculated safe levels were 4 for adults, 3 for teenagers and 1 for young children and toddlers. This was without making any allowance for mercury from the diet or the environment so the figures are, in fact, quite conservative. This report created intense opposition from the Canadian Dental Association which convened a ‘Panel of Experts’ (CDAEP) to review it. The panel report was compiled by Dr. Derek Jones, a professor in the faculty of dentistry at Dalhousie University in Canada. Unsurprisingly the panel disagreed with Richardson’s research. To determine the validity of the panel’s expertise, an assessment was made of each panel member’s research activity and their published works. Significantly, not one of the members had published any articles employing risk assessment protocols similar to that used in the Health Canada Report. A summary of the panel’s expertise is included (Part A, Appendix 2) and clearly demonstrates, based on their areas of academic expertise and published research, a severe lack of credibility as well as an obvious bias towards the pro-amalgam position. Another assessment, (Part A, Appendix 1) was carried out on the expertise and academic credibility of Canadian Dental Schools. This report, which has not been contradicted by any of the Dental Schools, reveals a decided lack of expertise in the Schools’ abilities to assess and comment on this issue. A similar assessment of Australian Dental Schools has not yet been done.

The main opposition to this report has been from the USA and Canadian Dental Associations, and derives from the Derek Jones report mentioned in the previous paragraph. It also needs to be stated, as Dr. Richardson has in his letter (Part B, pg 40) that Dr. Mackert, another active and published critic of the anti-amalgam position, was at that time, and may possibly still be, a paid consultant for Sybron Corp, a major USA amalgam manufacturer. A review which is being cited currently as supporting the safety of amalgams is the Eley article (Eley, B.M. The future of dental amalgam parts 1-7 British Dental Journal 182 247-459 & 183 11-14). ASOMAT has already expressed some concerns about Eley’s review in Part B (page ii). Eley raises a number of issues, derived essentially from the report by the CDA Panel, of which he was a member. In so doing Eley has made a number of mistakes and shown a lack of familiarity with the material and the risk assessment methodology, which Dr. Richardson has detailed in his response ( Part B page 40,). It is pertinent, as ASOMAT has already noted, that Eley’s review was not submitted to an appropriate journal where knowledgeable reviewers could assess the merits of Eley’s criticism. Rather it was submitted to one whose reviewers have no understanding of the subject. It bears repeating that Richardson’s report was peer reviewed by 16 national and international scientists, regulators and risk assessment specialists before submission to Health Canada and another 3 anonymous peer reviewers before being published in the journal ‘ Human and Ecological Risk Assessment’. The unquestioning acceptance, by those who should know better, of Eley’s observations about the validity of Richardson’s work is therefore quite perplexing. A comprehensive rebuttal of part of the Jones report is also included in the document (Part A, Appendix 10).

ASOMAT trusts that after evaluating the Richardson report, the reviews criticising the report and the rebuttal of those criticisms, that the Working Party will accept the Richardson report as a valuable contribution to our understanding of this issue.

Another frequently cited report, ‘Potential Biological Consequences of Mercury released from dental Amalgam, Proceedings from a State of the Art Conference in Stockholm April 1992 ’ is another example of political manouevering to achieve a biased and preconceived outcome. I refer the Working Party to the letter (Part A, Appendix 3) by Dr. Murray Vimy, a participant, expressing his disgust at the conduct of the conference. Included in the Appendices are two further critiques of reports which support the use of dental amalgams (Part A, Appendices 4, 9)

 

Why are these comments important?

They are important because when the amalgam issue is discussed the above studies are cited as ‘evidence’ of safety and are referred to by other reviewers in their own publications. By the sheer process of repetition they achieve a credibility which is undeserved when their efforts are analysed in an objective manner. This uninformed acceptance of poor science demeans the scientific process and it is therefore important that these studies are recognised as the amateurish, ill-informed and politically motivated works which they really are.

Another review often approvingly cited by amalgam supporters is the USA Health and Human Services Jan 1993 report. It was asserted in the April ’95 ADA News Bulletin, page 5, that this report concluded that there was no evidence to support the discontinuation of amalgam as a safe and effective filling material. A closer reading of the report itself would have revealed many statements in conflict with the official conclusion. To list just a few...

"This report is not intended to serve as the authoritative source on dental amalgam safety, but rather as a planning tool to assist policy makers in deciding on appropriate risk management actions."

"In the absence of adequate human studies, the subcommittee on risk assessment could not conclude with certainty whether or not the mercury in amalgam might pose a public health risk".

" Available data are not sufficient to indicate that health hazards can be identified in non-occupationally exposed persons. Health hazards, however, cannot be dismissed."

"The margin of safety may, however, be lower because body burdens of mercury are already high as a result of exposure to other sources: some persons may perhaps respond adversely to the incremental exposure to mercury derived from dental amalgams."

"The potential for effects at levels of exposure produced by dental amalgam restorations has not been adequately studied."

"The available research evidence is not specific enough or strong enough to make sound pronouncements about human health risks from dental amalgam."

 There are other similar statements. The above statements from the various work groups are clearly much more cautious than the official conclusion would suggest and it is inappropriate to cite this study as proving that amalgams are safe.

Another factor which ASOMAT feels is important and which the Working Party should consider is the persistent misrepresentation of the research by the various Dental Associations. In support of this statement ASOMAT includes (Part A, Appendices 5, 6), a copy of a fax and a transcript of that fax (to enhance legibility), in which the Director of Health Canada was forced to castigate the Canadian Dental Association for misleading its members and the general public with its printed matter. The American Dental Association also misrepresents the amalgam issue in general and, in particular, despite being informed that it is factually incorrect in so doing, persists in stating the Richardson report was rejected by Canada Health. To his credit, Dr. Butler, Executive Director of the Australian Dental Association has acknowledged the error of this statement and has not repeated it to Australian dentists. ASOMAT attaches a printout of the relevant AmDA Internet page (Part A, Appendix 7) and a copy of the letter sent to Dr. Richardson confirming that Health Canada not only accepted his report but deemed it properly done (Part A, Appendix 8). The significance of this is that dentists almost universally accept that what they are told by their Associations is accurate. Combined with a very selective reporting by the Associations of the relevant literature, the end result is that the dentists are particularly ignorant about even the existence of research which does not support the orthodox view. This also leaves them predisposed to dismiss alternative viewpoints with contempt and unwilling to even consider the possibility that there could be problems. The difficulties, from a medical, dental, financial and emotional point of view, which this creates for those patients who do have amalgam related problems and who are seeking some help, are enormous.

The original NHMRC brochure, prepared by the dental subcommittee, was withdrawn because the conclusions misquoted the only reference listed, a study by Alhqwist, which was cited as supporting them. Even if the correct Ahlqwist study had been cited there are serious deficiencies in both the Ahlqwist studies which preclude them from being a key study on which to base Australian Government health advice. The deficiencies arise from the fact that the women were divided into two groups; one with an estimated 20 or more surfaces of amalgam and the other, a "low amalgam" group with an estimated 0-4 surfaces of amalgam. There was no control group WITHOUT amalgam fillings, which would seem to be a desirable requirement if one is looking for differences between amalgam bearers and non-amalgam bearers. Not only was there no control group without any amalgams but many of the "low-amalgam" group probably have gold crowns with amalgam underneath (the researchers ignore the fact that amalgams are usually present under crowns, counted as a non amalgam in this study, which are not counted as amalgam surfaces). Theoretically, their mercury exposure could be higher than the "high-amalgam" group. Health status was determined by an unsupervised, self-administered questionnaire of symptom complaints. The researchers also forget that extracted teeth were probably amalgam bearing teeth providing mercury exposure before extraction (spaces do not count as possible amalgam sites in this study) The accuracy of the count of amalgams in the mouths is suspect and the numbers of participants do not add up. The 1988 abstract says that 1024 dentulous women were studied but the table 2 on following page lists only 653 in total. Clearly, the use of the Ahlqwist study is inappropriate in assessing the effects of amalgams in health.

ASOMAT would also like to bring to the attention of the Working Party the fact that in April 1998 the British Health Ministry sent over 50,000 letters to doctors and dentists advising them that amalgam fillings should not be placed or removed during pregnancy.

This is another indication, after the recommendations of Health Canada, the German Health Ministry and the Norwegian Government that the results of research in recent years are clearly showing that the use of dental amalgams needs to be limited, especially in vulnerable groups.

The ASOMAT recommendations which follow are a reasonable response to this issue and build on investigations already carried out by other governments which have accepted that dental amalgams are a significant source of heavy metal exposure. They are also preventive in nature. There is no call to have existing amalgams removed, just an acknowledgment of the fact that alternative, safer, materials are available and that a policy of preventing unnecessary exposure to mercury from dental treatment is not only feasible and reasonable, but justified by the growing scientific evidence of health problems in a small subgroup of the population. Implementation of the recommendations would be no different in nature and intent than the initiatives which removed mercury and lead from paints, and which are reducing lead from petrol.

 

Prevention is always better than cure,

- heavy metal toxicity is no exception !

 

 Dr. Roman Lohyn

President ASOMAT

June 1998

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