Mercury, a poisonous heavy metal and powerful neurotoxin, has long given doctors and environmentalists cause for concern. It is present in the environment, in fish, household products, medications, make-up, and vaccines where, in the form of thimerosal, it is used as a preservative for its antifungal and antibacterial properties.



Recent research at Columbia University (1) found autism-like damage in the brains of mice exposed to thimerosal. The study, in Molecular Psychiatry, used animals that had been bred to be vulnerable to developing disorders of the immune system. They argued it was possible that children with similarly compromised immunity may also be at risk of autism from exposure to the neurotoxc effects of mercury.



Other US and European studies (2,3) finding no link between mercury and autism or other neurological damage, claim however that he scientific evidence is not yet sufficiently strong to provide the same level of assurance for thiomersal-containing vaccines for use in pregnant women, or premature or low birth weight infants. “It is not possible to prove that thiomersal is completely safe - epidemiology can only quantify a risk, not prove its absence” (3).



The UK Government is now replacing a vaccine containing mercury given to eight-week-old babies with a five-in-one combined vaccine. The move comes amid fears of a link with mercury and autism, leading to a decrease in compliance for infant vaccination, and has been widely welcomed by anti-mercury pressure groups. The UK Department of Health has always maintained that there is no evidence of a link, but that the new vaccine is “more effective”. According to a BMJ editorial,

“regulatory bodies have recommended its [thiomersal] removal in accordance with the precautionary principle as long as this is not to the detriment of the vaccine programme” (4).



The new vaccine will also dispense with use of the live polio vaccine, currently given by mouth, to an injectable "killed" vaccine to avoid spreading the polio virus. The five-in-one injection will contain vaccinations for diphtheria, tetanus, whooping cough, Hib and polio, and is to be introduced when current vaccine stocks are depleted.



The UK National Autistic Society said it had always "supported moves to ensure that mercury is not used" in vaccines. Thimerosal is however still used in some vaccines (5).



The Columbia University study says: “The developing brain is uniquely susceptible to the neurotoxic hazard posed by mercurials. Host differences in maturation, metabolism, nutrition, sex, and autoimmunity influence outcomes.” Mice bred to have poor immunity showed amongst other effects, “exaggerated response to novelty”. The researchers concluded that “these findings implicate genetic influences and provide a model for investigating thimerosal-related neurotoxicity”. The animals in the study had been bred to be vulnerable to developing disorders of the immune system.



Toxins should not ideally be routinely introduced into the population, but as mercury toxicity is now known to be influenced by genetics this is surely a reason to remove it from all vaccines.



High-dose probiotics have been shown to be an effective adjunct to chelation therapy when detoxifying from heavy metals, particularly in relation to autism (6). Given the widespread presence of heavy metals such as mercury it would make sense to include probiotics as part of an immunity programme, rather than the current reliance on immunisation. Paying attention to genetic differences in immunity, such as blood group and secretor status, can play a very important part in disease prevention when coupled with a naturopathic approach.



The opinion of Ian Pennell, consultant psychiatrist, responding to the claim that a lack of exposure to bacteria has created an increase in allergies, appears far more rational than using neurotoxic chemicals in preparations that artificially stimulate the immune system:



“The hypothesis… states that increasing microbiological sterility in our environment produced by constant routine dousing of our houses and ourselves with antibacterial chemicals in the name of hygiene, generates an abnormal set of immunological responses resulting in allergies.



“A better response to all this would be for children to be encouraged to play in the dirt, for us all to use soap in our homes rather than antibacterial cleanser, and to confine disinfectant to around the toilet rather than on all available surfaces. Eating live yoghurt might also help, as might encouraging frequent and regular physical contact with our pets, for both psychological and immunological reasons.



“I would much prefer to live out this sort of existence than be forever dependent on medical technology to bolster an immune system fatally weakened by a life long obsession with hygiene and a preoccupation with maintaining a sterile barrier with the natural world. (7)”



1. Hornig M, Chian D, Lipkin WI. Mol Psychiatry. 2004 Jun 8. Neurotoxic effects of postnatal thimerosal are mouse strain dependent.

2. Immunization Safety Review: Vaccines and Autism .

3. Clements CJ. The evidence for the safety of thiomersal in newborn and infant vaccines. Vaccine. 2004 May 7;22(15-16):1854-61.

4. BMJ 21 August 2004;329:411-412. Editorial: Misconceptions about the new combination vaccine.

5. Institute for Vaccine Safety. Institute for Vaccine Safety



6. Brudnak MA. Med Hypotheses. 2002 May;58(5):382-5. Probiotics as an adjuvant to detoxification protocols.

7. Pennell, I. Exposure to real life, not vaccination should be the answer. BMJ 24 May 2004.