Thiomersal

House of Lords written question – answered at on 16 December 2002.

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Photo of Lord Hodgson of Astley Abbotts Lord Hodgson of Astley Abbotts Conservative

asked Her Majesty's Government:

How many of the standard vaccinations that children receive in the United Kingdom contain thiomersal; for how many years these standard vaccinations have contained thiomersal; and what research has been carried out into the cumulative effects of the mercury content of thiomersal on infant children.

Photo of Lord Hunt of Kings Heath Lord Hunt of Kings Heath Parliamentary Under-Secretary, Department of Health, Parliamentary Under-Secretary (Department of Health)

Vaccines containing thiomersal (a mercury-containing compound known as thimerosal in the United States) have been in use for over 60 years. The only vaccines used in the routine United Kingdom childhood immunisation programme which contain thiomersal as an excipient in the final product are diphtheria, tetanus and whole cell pertussis (DTwP) and diphtheria and tetanus vaccines.

In 2001, the Committee on Safety of Medicines (CSM) reviewed the available data relating to possible neurotoxicity of thiomersal in vaccines and advised that there is no evidence of harm caused by doses of thiomersal in vaccines. The CSM concluded that the risk: benefit balance of thiomersal-containing vaccines remains overwhelmingly positive. The Institute of Medicine (IOM) in the United States also published a detailed review of the evidence relating to possible neurotoxicity of thiomersal in vaccines in October 2001. The IOM findings were consistent with the CSM conclusions.

We are aware of two new studies in the UK looking at the relationship between mercury in vaccines and neurodevelopmental disorders in children. One of these studies is funded by the Department of Health and uses the Avon Longitudinal Study of Pregnancy and Childhood. The other study is using the General Practice Research Database and is funded jointly by the World Health Organisation and the Public Health Laboratory Service (which receives its funding from the department). Neither of these studies supports an association between thiomersal exposure through the UK programme and neurodevelopmental disorders in children. The results of these studies have been made available to the department and a summary of the findings is available in a report to the US Congress which has been placed in the Library.

In addition to the above studies, evidence from a recent study by M Pichichero et al (published in the November 30 2002 Lancet) showed that giving vaccines containing thiomersal does not raise blood levels of mercury. The findings of this paper suggested that ethylmercury is rapidly eliminated from the blood after administration intra-muscularly. The levels of ethylmercury in the blood were no higher than in samples taken at birth—before any vaccines had been received.

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