Thimerosal 273Geier et al. [64] evaluated the mercury exposure among the cases and con-
trols by utilizing the vaccination database and included individuals who received
no doses of HepB vaccine. A comparison was made between the children who
received HepB that contained mercury (12.5 μg of mercury per dose is present
in that particular vaccine) to those receiving 0 μg mercury per dose for those
receiving either combined haemophilus influenza type b (Hib)‐hepatitis B vaccine
(a thimerosal‐free hepatitis B vaccine) or neither of the aforementioned vaccines.
The dosing of thimerosal‐containing mercury cases and controls during the
first 6 months of life ranged from a minimum of 0 μg thimerosal‐containing
mercury (for children receiving no doses of hepatitis B vaccine and/or Hib‐
hepatitis B vaccine) to a maximum of 37.5 μg thimerosal‐containing mercury
(from children who received three doses of Hepatitis B vaccine). Analyses
showed that children who were diagnosed with regressive (atypical) autism
were significantly more likely to have received increased doses of mercury from
thimerosal‐containing hepatitis B vaccines than controls within the first month,
within the first 2 months, and within the first 6 months of life. They also
observed, by using the logistic regression statistical test, that cases diagnosed
with regressive autism in comparison with controls were in a dose‐dependent
fashion more likely to have received increased mercury doses from thimerosal‐
containing hepatitis B vaccines administered within the first 6 months of life.
In this chapter, we will not be able to discuss in detail all the pro‐vaccine
versus anti‐vaccine groups and their views. However, we would like to sum-
marize the support of the hypothesis that thimerosal‐containing vaccines may
deliver a toxic amount of mercury to neonates, toddlers and young children
that may increase risks for regressive autism in susceptible individuals.
Why Thimerosal‐Containing Vaccines are Harmful: A Scientific Narrative
In a simple scientific manner, we can state that thimerosal‐mercury causes
oxidative stress [65,66]. Studies find higher levels of oxidative stress in
autism spectrum disorder (ASD) and the degree of oxidative stress levels are
observed to be higher in individuals with more severe symptoms of ASD [67].
There have been numerous reports of immune dysfunction associated with
ASD. We have discussed this topic in the previous chapter.
The study of Geier et al. [64] confirms previous studies and validates the studies
that examined the medical diagnoses of ASD, autism spectrum, pervasive develop-
mental disorders or regressive autism and found a significant association between
thimerosal‐containing mercury exposure and regressive autism. For example, an
ecological study of the vaccine safety datalink database for the birth cohort preva-
lence of ASD in comparison with the average thimerosal‐containing mercury dose
infants received by birth cohort revealed a significant dose‐dependent increased
risk of diagnosed ASD that correlated with the increasing microgram thimerosal‐
containing mercury exposure within the first 7 months and the first 13 months of