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There's no room for complacency over mercury-autism link

Your news report (November 24) that a US Government study1 has provided further reassurance that there is no link between autism and mercury-containing vaccines only tells part of the story.

A first draft of this study in February 2000, of which I hold a copy marked 'confidential' and 'do not copy or release', found a relative risk of developing autism of 2.48 in children receiving 62.5µg or more of mercury by three months of age.

Children in the UK receive 75µg of mercury (25µg in each DPT) by around four months. Manipulation of the data resulted in the June 2000 version of the study, which showed a reduced relative risk of developing autism of 1.69. The authors then added further data from an additional health maintenance organisation in Massachusetts.

It may be no coincidence that this HMO went into receivership at the time the data was being collected. It had multiple computer systems that were in shambles and unable to communicate with each other2. Even more remarkably, Massachusetts was at that time showing a far lower prevalence rate of autism than every other US state.

In June 2000 a meeting was held between the authors of the study, members of the US Centers for Disease Control and Prevention (CDC) and the vaccine industry. Transcripts of that meeting have been obtained in which the lead author, Dr Thomas Verstraeten, reports that, although the significant association between mercury exposure and language delay is quite large, all adverse outcomes were likely to be larger than obtained in the study because many children used in the study were simply not old enough to be diagnosed ­ some were less than two years old.

Those attending the meeting were also reported as saying they could push and pull the data anyway in order to get the results they wanted and alter the exclusion criteria any way they wanted, giving reasonable justifications, and get the results they wanted. One said he would not give thiomersal (mercury)-containing vaccines to his grandson3.

Perhaps not surprisingly I am not reassured by the conclusion of the latest incarnation of this study which states: 'No consistent significant associations were found between thiomersal-containing vaccines and neurodevelopmental outcomes.'

Your readers might also like to know that Dr Verstraeten left the CDC to join vaccine manufacturer GlaxoSmithKline in 2001.

It is also of note that while the US, along with most European countries, has withdrawn mercury-containing vaccines from their immunisation schedules, our Department of Health continues to recommend mercury-containing vaccines for the infant immunisation schedule, even though there are licensed, safe and effective alternatives.

Let us hope our children do not have to pay too high a price for this complacency.

Dr Richard Halvorsen

London WC1N

1 Verstraeten at al. Pediatrics, vol. 112 No. 5 November 2003, pp. 1039-1048

2 Miller HF et al. Journal of Law, Medicine and Ethics, September, 2000

3 Dr Dave Weldon (US Congressman) in a letter to Julie Gerberding, Director, CDC, October 31, 2003

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