In Dr Sehmer’s warning [BCMJ 2001;43(6):320 [9]] about dubious mercury poisoning results, is he seriously suggesting that mercury is not toxic, that dental amalgams are not a significant source of mercury, and that Doctor’s Data of Chicago are reporting spurious results? Can he produce one primary research article that scientifically proves that mercury is either non-toxic or does not leach out in significant amounts from dental amalgam fillings?

Gross and Jarrison have shown in vivo studies that a single amalgam with an occlusal area of 0.4 cm on average would release 15 micrograms a day or half of the amount stipulated as safe by the US Environmental Protection Agency! [1] Fleva has shown experimentally that corrosion of amalgams releases about 30 micrograms a day.[2] He also calculates that the transition of only 1 gram of gamma-1 (Ag2Hg3) to AgHg in 10 years would release 170 000 micrograms of Hg, giving an exposure of 46 micrograms a day.

Dr Sehmer’s remarks that levels of Hg 20 to 30 times that of the reference levels reported by a Chicago lab are not alarming when reported by a conventional lab is as confusing as it is misguided. Doctor’s Data, a major US laboratory, participates in a voluntary quality control program where known concentrations of heavy metals are randomly tested. Their accuracy approaches 100%. I find Quack Watch to be a biased web site with very little primary research.

I would recommend he read Does Mercury from Dental Amalgams Influence Systemic Health? by Gary A. Strong.[3] This author has collected over 300 primary scientific articles on the effects of mercury in the human body.

It is presumptuous to remove potential hope of treatment to the 5% of patients acknowledged by the ADA to be highly sensitive to mercury.

—Peter J. Nunn, MB 
Victoria

Dr Nunn has a complementary and general practice and has been using chelation for heavy metal problems for the last 6 years.—ED.