Scientists applaud move away from use of mercury
By Roger Highfield, Science Editor
(Filed: 10/08/2004)
Source: News Telegraph.co.uk
Scientists searching for a link between mercury and damage to the developing brain welcomed yesterday's decision to remove the mercury-based preservative from childhood vaccines.
Dr David Salisbury, the head of immunisations at the Department of Health, said the decision had nothing to do with concerns over a link between the preservative thiomersal and autism.
But the reality is that the effects of the preservative are not fully understood, according to a British professor who has discovered that thiomersal accumulates and changes in the brain.
Prof Graham George, of the University of Saskatchewan in Saskatoon, Canada, is studying the fate of mercury in the body, since the toxicity of organic compounds of this metal critically depends on their molecular form and other factors, such as the presence of selenium.
Advances in x-ray technology have enabled Prof George's team to collect information that has eluded scientists in the past and it is now studying the transformation of thiomersal (called thimerosal in America) in the body.
Prof George stressed that his findings are preliminary but "indicate that mercury administered to rabbits as thimerosal does accumulate in the brain in a relatively short time". Thiomersal is taken up in "about an hour" and is chemically modified, though he would not be more specific because the work has not been published.
However, "it is a very good thing that it is coming out".
He said: "It shocked me when I found out it is in vaccines. If you wanted to chose something to put into a vaccine, and you were doing it fresh, thiomersal would be the last thing.
"It is known to be neurotoxic and would never get approval for drug use these days. It is only because it has been 'grandfathered in' since the 1930s that it is in use at all.
"I made sure my kids did not get mercury in their vaccines and, when my wife was pregnant, she did not have flu shots. Pregnant women who receive the flu vaccine get a great big dose of thiomersal and it is pretty well established where that will end up - in the brain of the foetus or the kidney."
He would "not be surprised" if there is a link with autism.
In the journal Molecular Psychiatry, a mechanism linking the preservative to such developmental disorders has been set out by Prof Richard Deth of Northeastern University and colleagues.
Despite the reasons given for its removal by the Department of Health, the move will decrease the risk of developmental disorders, Prof Deth said yesterday.
