***THE AUTISM WARS Part Four: Pros and Cons

Time now to turn our attention to the USA where the arguments surround one particular vaccine additive - thimerosal  - rather than the vaccines themselves.  This mercury based product has been used  as a preservative in many vaccines since the 1930s - before being removed from many of them at the beginning of this century.   Thus it was in the Diphtheria, Pertussis and Tetanus vaccine (DPT)  vaccine routinely given children from two months of age,  although it was not used in the Measles, Mumps and Rubella vaccine.

Many in the pro-vaccination lobby still argue that thimerosal has no adverse side effects - and certainly does not cause autism.  And yet as ever we run into the same old problem of trying to prove a negative for it is impossible to argue that a particular substance does not cause a problem when you cannot actually define how that problem arises in the first place. 
It has been argued that my latter point is a naive one.  I'll have to leave you to judge whether that is really true for this brief article does not allow me space enough to answer in full.  For now I will simply address the effects of thimerosal itself by looking at some of the many studies that have been done to date.    

Putting autism aside for a moment we find that studies done in other countries in the 1970s and 80s,  raised grave concerns;  one Russian study finding that adults exposed to ethyl-mercury, (the same form of mercury as in thimerosal), suffered from various health problems in later life,  involving the  nervous system, the adrenal system function, vascular lesions of the brain etc. 

Hardly surprising then that Russia banned thimerosal from children's vaccines in 1980: a course followed by many other countries including Japan, Great Britain and all the Scandinavian countries though not the United States.   It is seemingly common for scientific endeavor in one country to be ignored by other countries – who then frequently go to the expense of doing their own studies - but surely that Russian study and others done subsequently should have rung alarm bells?

Despite that,  most of the studies in the US have seemingly focused on the possible links with autism.  To date all seemingly deny any evidence of such a link with one study even suggesting that infants exposed to the highest levels of thimerosal were no more likely to develop autism than infants exposed to only a small amount. 

Strange, for it is known that thimerosal has several adverse effects.  One,  it is genotoxic (damaging DNA molecules in genes and causing mutations etc.).  Secondly it has also been implicated in damaging mitochondria and thirdly it can inhibiting one of the important detoxification enzymes: both of which are often associated with ASD.

Certainly the CDC and the American Association of Pediatrics must have had some worries for,  in 1999,  they issued a joint statement asking the manufacturers to remove it from their vaccines voluntarily - as a precautionary measure even though no 'evidence of harm' existed - because some children might  get more than the recommended limit for mercury at their six month visits.

This withdrawal process actually began in 1999 but,  unfortunately, even after it announced that its new line of vaccines were preservative-free one manufacturer continued to distribute their remaining stockpile of thimerosal-preserved vaccines - only stopping after a congressional inquiry. 

In the late 1990s the Center for Disease Control (CDC) commissioned Dr. Verstraeten, an epidemiologist,  to study the Vaccine Safety Datalink to determine whether there was any risk of autism or other neuro-developmental delay associated with thimerosal exposure. 

A positive attempt to find the truth?  You might hope so.  And yet the answer to that is certainly not a simple one for, as documents obtained through the Freedom of Information Act by 'Safe Minds' (an organization funded primarily by parents of autistic children) show,  the findings were somewhat controversial.

Thus the initial draft found an increase in several neuro-developmental problems from tics and attention deficit disorder to language and speech delays etc. Unfortunately though, after a number of  discussions, when the study was finally published in November 2003 the findings seemed to have been diluted for it concluded by saying that 'no consistent significant associations were found between thimerosal-containing vaccines and neuro-developmental outcomes'.  

That was a rather surprising conclusion to anyone who had read the first draft.  While some people were even more concerned when they found that, by the time it was published,  the lead author was working for a vaccine company,  he stood - and still stands - by the conclusions it drew. 

Today the pro-vaccinationists (if that is the correct term) have now found another argument - saying that thimerosal must now be exonerated as a cause because - even though it has been removed from most vaccines,  the incidence of ASD is continuing to rise. 

And yet that too is somewhat misleading, because thimerosal is still used  in some of the multiple-dose influenza shots.  Given some of the side effects of influenza this is seen as a real benefit with the CDC estimate that 79,000 flu hospitalizations were avoided in the 2012 - 2013 flu season.  However it also means that flu shots containing thimerosal are being given to some pregnant mothers during the 'flu season'  - and are also being given to some infants over six months old.  

Meanwhile some people continue to suggest that the rise in ASD is attributable to better diagnosis others believe that a relationship between the increase in neuro-developmental disorders and thimerosal is plausible. 

The arguments look set to continue for some time.  Shall we ever know the truth?  I think we will.  Join me in my forthcoming series if you want to know more. 

Adapted from The Source Code - the third book in the new series The Autism Code.