http://bmj.bmjjournals.com/cgi/eletters/329/7466/588-b#99309

Aasa Reiddak was surprised by the case history about mercury amalgams and developmental dyslexia. Dr John McLaren-Howard and I posted Biolab findings in 61 autistic children previously on this site on 13 September, 2004.

Three of the 61 children had DNA-adducts in leucocytes to mercury, 16 to malondialdehyde, 12 to cadmium, 9 to nickel and one to lead.1 Lymphocyte sensitivity tests (results below 100 are regarded as normal) are more sensitive than serum levels for detecting harmful effects of metals. The mother of the dyslexic children had definite sensitivities to inorganic (dental) mercury and nickel (380 and 220) and mild sensitivities to vitallium (dental Cr/Co) silver, cobalt, and tin (165, 160, 155, 115) before the removal of all dental metals. Organic mercury (from fish) lymphocyte sensitivity was 90 but fell to 17 after chelation. All the metals retested for lymphocyte sensitivity produced low normal results (86 -1) after chelation.

The work of Haley and colleagues is very interesting. In a group of 94 autistic children, hair mercury levels varied significantly across those mildly, moderately, and severely autistic, with mean group levels of 0.79, 0.46, and 0.21 ppm, respectively.2 Hair mercury levels among controls were significantly correlated with the number of the mothers' amalgam fillings and their fish consumption as well as exposure to mercury through childhood vaccines, correlations that were absent in the autistic group. Hair excretion patterns among autistic infants were significantly reduced relative to control.

In 1981 we had found, in the hair of 73 dyslexic children, significantly higher levels of cadmium and lead, but not mercury.3 Were some of the dyslexic children mildly autistic perhaps? In 1983 Rimland and Larson review 51 hair mineral analysis studies and found that high levels of cadmium, lead and mercury were associated with undesirable behaviour.4 In 1988, using a mineral profile of sweat, hair and serum, most of 26 dyslexic children were zinc deficient in their sweat and had significantly lower levels of zinc, chromium, copper and higher levels of lead and cadmium in their sweat compared with their matched controls. Sweat mercury was not tested. In the hair of dyslexic children, mercury, copper, lead, and cadmium levels were significantly higher compared with controls. 5

Haley and colleagues carried out an experimental study in rats because mercury vapour (Hg0) is continuously released from "silver" amalgam tooth fillings and is absorbed into brain. The rats were exposed to Hg0 4h/day for 0, 2, 7, 14 and 28 days at 250 or 300 micrograms Hg/m3 air, concentrations present in mouth air of some humans with many amalgam fillings.6 Average rat brain Hg concentrations increased significantly (11 -47 fold) with duration of Hg0 exposure. By day 14 Hg0 exposure, photo affinity labelling on the beta-subunit of the tubulin dimer in brain homogenates was decreased 41-74%. The identical neurochemical lesion of similar or greater magnitude is evident in Alzheimer brain homogenates from approximately 80% of patients, when compared to human age-matched neurological controls. The authors concluded that chronic inhalation of low-level Hg0 can inhibit polymerization of brain tubulin essential for formation of microtubules.

It is a pity to waste money on misleading, repetitive and irrelevant epidemiological studies. There is enough hard evidence that mercury amalgams should no longer be used.

1 Grant ECG, McLaren-Howard J. Re: The effects of toxic metals in autistic children http://bmj.com/cgi/eletters/329/7466/588-b#74117, 13 Sep 2004.

2 Holmes AS, Blaxill MF, Haley BE. Reduced levels of mercury in first baby haircuts of autistic children. Int J Toxicol. 2003; 22: 277-85.

3 Capel ID, Pinnock MH, Dorrell HM, Williams DC, Grant ECG. Comparison of concentrations of some trace, bulk and toxic metals in the hair of normal and dyslexic children. Clinical chemistry 1981; 27: 879-81.

4 Rimland B, Larson GE. Hair mineral analysis and behaviour: An analysis of 51 studies. J Learning Disabilities 1983:16: 1-4.

5 Grant ECG, Howard JM ,Davies S, Chasty H, Hornsby B, Galbraith J. Zinc deficiency in children with dyslexia: concentrations of zinc and other minerals in sweat and hair. BMJ 1989; 296: 607-9.

6 Pendergrass JC, Haley BE, Vimy MJ, Winfield SA, Lorscheider FL.Mercury vapor inhalation inhibits binding of GTP to tubulin in rat brain: similarity to a molecular lesion in Alzheimer diseased brain. Neurotoxicology 1997; 18: 315-24.

Competing interests: None declared

A mother had many teeth filled with mercury amalgam in her teens and twenties and gave birth to three children when she was still in her 20s. All were dyslexic, two of them being severely affected which impaired their otherwise exceptionally high IQs. After 50 years of daily episodes of severe tiredness, and after not completely successful attempts to remove concealed mercury amalgams, the mother became allergic to the remaining metals in her teeth, with a burning tongue and lip swelling.

Tests revealed:-

Blood mercury 6 ug/l (population mean 1.9)

Lymphocyte sensitivity test for inorganic mercury 380 (normal below 100)

Urine mercury level 9 ug/l

Mercury/creatinine ratio 4.32 nmol Hg /nmol of creatinine (usual level < 2.0)

Six months after all metals were removed from her mouth and daily use of Chlorella chelation and essential nutrient supplementation, the mother’s results were:-

Lymphocyte sensitivity test for inorganic mercury 44 (normal below 100)

Urine mercury level 3 ug/l

Mercury/creatinine ratio 2.3 nmol Hg/nmol of creatinine (usual level < 2.0)

The tests were performed at Biolab Medical Unit, London. The patient wonders why toxic mercury is still being used by dentists.

Competing interests: None declared

Editorial note
The patient whose case is described has given her signed informed consent to publication.