While reading up on papers about vaccinations, I found out that some vaccines contain thimerosal which is a compound well known for its antiseptic and anti-fungal usages. Thimerosal contains toxic ethyl mercury. Thimerosal was used as a preservation component for some vaccines used for children and pharmaceutical products to avoid bacterial and fungal growth. Thimerosal has been found as a possible risk factor for autism. In the United State, the Centers for Disease Control and Prevention estimates that the current prevalence of Autism Spectrum Disease (ASD) to be 1 in 110 children (Centers for Disease Control and Prevention 2010).
In another paper I read through, a total of 109,863 children from the United Kingdom were exposed to thimerosal based on the number of DTP (diphtheria-tetanus-pertussis) and DT (diphtheria-tetanus) vaccinations. The study kept track of subjects’ gender, year of birth, month of birth, but not for other potentially confounding variables. Also, there was no apparent association seen between thimerosal and autism in the control numbers. In addition, a recent study done by Hertz-Picciotto shows that the level of mercury concentration in blood was not elevated or reduced. Therefore, there is no relationship between ASD and the mercury level in blood.
In conclusion, both studies show that thimerosal does not cause ASD or neurological disease. They do suggest that the topic requires more study in the near future. It will be interesting to see if thimerosal really does have any correlation with autism.
Andrews N, Miller E, Grant A, Stowe J, Osborne V, Taylor B (2004) Thimerosal exposure in infants and developmental disorders: a retrospective cohort study in the United Kingdom does not support a causal association. Pediatrics 114: 584–591.
Hertz-Picciotto I, Green PG, Delwiche L, Hansen R, Walker C, Pessah IN (2010) Blood mercury concentrations in CHARGE. Study children with and without autism. Environ Health Perspect 118: 161–166.
I just read a paper also published by the CHARGE study that reported that children with autism and autism spectrum disordes have IgG antibodies that target specific brain proteins that are not present in normal controls. For these antibodies to be pathogenic, they must pass through the blood brain barrier. The authors note that infections, extreme stress, and environmental factors can increase the permeability of the bbb and may allow the antibodies to access the brain. One such toxoid is tetnus toxoid. Did the researchers look at whether tetnus and not thimerosol could be the risk factor?
ReplyDeleteWe had to take down the comments by an outside person, which were full of errors and misconceptions. It is a sad example of the issues that parents have to face when they are looking for information about immunization.
ReplyDeleteI would closely question an claim that tetanus toxoid, administered to almost everyone in the developed world (does anyone know someone here, in the states, who hasn't been vaccinated against tetanus?) has potential as an inducer of autism. If that were the case, I think that the prevalence of autism and autism-spectrum disorders would be much higher. Plus, lockjaw is a horrible way to die. I'd rather be a little weird than get tetanus.
ReplyDeleteI did, however, hear an interesting (though un-substantiated) claim that there is a correlation between the rising use of online-dating services and the increased-diagnosis of autism-spectrum disorders. Could it be that we've fingered the wrong scapegoat and that the culprit here is really websites pairing up the socially-awkward?