For some time now, there has been a debate as to whether the preservative thimerosal, which is added to some vaccines, is linked to autism.

 

It is claimed that thimerosal attacks the central nervous system and can trigger autism. There is no scientific proof that thimerosal can cause autism. Over the past 15 years, scientists around the world have repeatedly conducted new experiments, but have been unable to recognise any connection between thimerosal and an increasing rate of autistic children. Thimerosal is now hardly used as a preservative.

 

Thimerosal has been added to some vaccines for around 70 years to prevent the growth of bacteria and fungi. Originally, vaccines were stored in large containers from which individual doses were taken as required. With each withdrawal, the vaccine was exposed to bacteria. In the 1920s, there were a number of deaths from contaminated vaccines, after which preservatives began to be added to the vaccine serum. As vaccines are now mainly stored in single doses, the addition of thimerosal is no longer essential, although this makes the manufacturing process less economical.