Statement of Grounds – Flaws in the FDA amalgam Rule

FDAOn July 28, 2009, FDA announced that it was classifying dental amalgam for the first time in Class II without requiring any significant special controls. FDA’s Final Rule on this issuewas published on August 4, 2009. FDA also published an Addendum in support of its Final Rule, in which it explained its attempts to address the recommendations of the Joint Panels that convened in September 2006 and rejected the conclusions in the FDA White Paper on amalgam fillings.

Mercury fillings must be banned from the market [12 U.S.C. §360f] or classified in Class III. [12U.S.C. §360c] These fillings are not safe and should be removed from the market, just as everyother mercurial medical device and substance has been. At the very least, they should be placed in Class III so that the amalgam manufacturers are required to prove that they are safe. Mercurial wound disinfectants are gone, mercurial diuretics are gone, mercury thermometers are gone, and so are all mercurial veterinary substances. There is no magic that makes dental mercury safer than those obsolete products of the past. In this era when the public is advised to be concerned about mercury exposure through fish consumption, the FDA should ban mercury fillings as the predominant source of mercury exposure in the general population.

There are several obvious flaws in the FDA’s Final Rule, as follows:

  1. FDA Final Rule on the classification of dental amalgam is based on a superficial and inadequate review of the literature.
     
  2. The estimated mercury vapor exposure from dental amalgam is incomplete, illcomposed, ill-conceived, indefensible, and inaccurate.
     
  3. An effective and defensible risk assessment for mercury vapor complies with EPA(2004, 1998, 1994) and the National Academy of Sciences (NAC, 2008).
     
  4. FDA fails to utilize a methodical analysis of the ‘weight of evidence’ of the toxicological literature.
     
  5. FDA offers no detailed quantitative analysis of its toxicological database leading to the determination of a defensible regulatory reference exposure level.
     
  6. FDA fails to utilize a methodical, transparent, and defensible quantification of exposure for comparison to that reference exposure level.
     
  7. FDA makes no defensible attempt to compare the full range of Hg° exposures across the entire amalgam-bearing U.S. population to regulatory reference exposure levels designed and intended to protect the general population.
     
  8. FDA only considers exposures attributed to a maximum of ten filled teeth, and only in adults, but incorrectly assumes this also applies to children six years and older.
     
  9. The FDA ignores children younger than six years, but children as young as three years receive amalgam fillings.
     
  10. The FDA ignores persons with more than ten amalgam fillings, but adults often have up to twenty-five (and possibly more) amalgam-filled teeth.
     
  11. The FDA makes no attempt to determine the number or percentage of Americans excluded from its risk assessment.
     
  12. The FDA omits to quantify the full range of Hg° exposure across the entire population, in all relevant age groups.
     
  13. The FDA omits to quantify the proportion of the amalgam-bearing population that exceeds the EPA RfC and the ATSDR MRL, the two reference exposure levels that purportedly provide health protection to the non-occupationally exposed general population.
     
  14. The FDA omits to quantify the exposure in children less than six years of age, an age group considered the most vulnerable to exposure and adverse effects and a population group that does, indeed, receive amalgam fillings.
     
  15. Many of the FDA calculations in the final rule are in error, in part due to improvident reliance on outdated or non-authoritative sources of information.
     
  16. FDA utilizes unreliable values for its assumed inhalation rate; FDA relies on EPA’s RfC but inexplicably fails to recognize EPA (1997; 2008) as the most nationally and internationally authoritative information source on human inhalation rates.
     
  17. The RfC-associated dose and MRL-associated dose is improperly extrapolated to apply to children. These doses should only be derived for adults, the age group studied in the occupational studies upon which the RfC and MRL are based.
     
  18. FDA fails to adjust inhaled dose for the 80% absorption of mercury vapor in the lungs.
     
  19. FDA fails to standardize the internal doses associated with the RfC and MRL (and those from amalgam) to body weight due to the great disparity in body weights in the different age groups being considered.
     
  20. Contrary to the FDA’s statement, the WHO Environmental Health Criteria 118(WHO 1991) did not “[find] that values generally in the range of 1-5 μg/day were estimated in the U.S. adult population”. Rather, WHO (1991) concluded that “estimated average daily intake and retention” from dental amalgam was 3.8-21 (3-17)μg/day (values in brackets representing retained (absorbed) dose (WHO, 1991, Table 2).
     
  21. Contrary to FDA’s assertion, the WHO (2003) did not conclude that “[t]he highest estimate that WHO reports was a dose of 12 μg/day, for middle-aged individuals with approximately 30 amalgam surfaces (Ref. 22).” In the Executive Summary of this document (WHO 2003), WHO clearly states “[d]ental amalgam constitutes a potentially significant source of exposure to elemental mercury, with estimates of daily intake from amalgam restorations ranging from 1 to 27 μg/day.”
     
  22. Based on FDA’s method of estimating Hg° exposure from dental amalgam, and assuming that the RfC is derived correctly, the number of fillings necessary to exceed the RfC are:
    1. Child 3-6 yrs – 2 fillings.
    2. Child 6-11 yrs – 2 fillings.
    3. Teen 12-19 yr – 3 fillings.
    4. Adults – 7 fillings.
       
  23. Based on FDA’s method of estimating Hg° exposure from amalgam, and assuming the MRL is derived correctly, the number of fillings that result in exceeding the MRL are:
    1. Child 3-6 yrs – 2 fillings.
    2. Child 6-11 yrs – 2 fillings.
    3. Teen 12-19 yr – 4 fillings.
    4. Adults – 5 fillings.
       
  24. The FDA has inadequately quantified Hg° exposure in, or totally omitted to consider, the following Americans:
      1. 428,000 American toddlers aged three and four years that possess amalgam filled teeth
      2. , and 260,000 of these toddlers that would exceed the MRL equivalent dose of mercury from their amalgam fillings, and 61,000 toddlers who would exceed the RfC-equivalent dose for mercury.

       
  25. The FDA failed to recognize or rectify the inadequacy and non-valid nature of the EPA RfC or the ATSDR MRL:
    1. The EPA categorizes mercury vapor as a neurotoxin but the RfC has not yetbeen revised and updated to comply with EPA’s (1998) guidance on theassessment of neurotoxins nor the guidance provided by the National Academy ofSciences (NAS 2008).
    2. The EPA acknowledged as early as 2002 that significant new literature wasavailable on the toxicity of mercury vapor; FDA cannot properly cite EPA’s lackof action to revise the RfC and address the new literature as ‘evidence’ of the lackof new and significant studies.
    3. The reviews by EPA (1995) and the ATSDR (1999) are not recent, asindicated by FDA; the EPA RfC cites no literature later than 1995, now somefourteen years out-of-date. The most recently dated citation within the ATSDRToxicological Profile on Mercury (ATSDR, 1999) is 1999, now some ten yearsout-of-date.
    4. FDA claims to have reviewed relevant literature up to July 2009, but it failedto locate Health Canada (2006), Richardson et al. (2009), Ratcliffe et al. (1996),among many other relevant studies and reports, discussed below.
    5. The FDA failed to recognize that studies of workers at chloralkali plants,where concomitant exposure to mercury vapor and chlorine gas occurs, are invalidfor establishing reference exposures levels for non-occupational exposure to Hg°.
       
  26. Mercury has been identified in a large number of peer reviewed studies as being alikely causes of the more prevalent neurological disorders such as Alzheimer’s Disease,severe autism, multiple sclerosis (ms), amyotrophic lateral sclerosis, and Parkinson’sDisease. Mercury also causes hearing loss, periodontal disease, kidney dysfunction, and allergy.
     
  27. FDA failed to prepare an environmental impact study, or at least an environmental assessment, in violation of the National Environmental Protection Act.
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