Front Matter

Thimerosal 275

We have described the role of BBB and how it prevents entry of any
unwanted chemicals into the brain. However, there are events that can
make a young child’s BBB transiently leaky [80–82]. In our own research,
we have discovered that there are cytokines that, if present, can make a
child’s BBB leaky. The BBB is a filtering mechanism of the capillaries that
carry blood to the brain and spinal cord tissue, blocking the passage of
certain substances. Therefore, in any normal circumstances the BBB can
prevent the entry of any neurotoxic agent(s) including thimerosal or mer-
cury into the brain. However, there are certain immunologic conditions
that would make a BBB slightly leaky. The transient leakiness of the BBB
can now be deciphered through various methods [81]. Many epidemiologi-
cal studies have shown inflammatory cytokines can make a neonatal BBB
leaky [82–86]. Inflammatory cytokines are types of immune signaling mol-
ecules that are released from T‐lymphocytes, macrophages and mast cells
that increase inflammation. Inflammation sometimes causes fever but also
can make the BBB transiently leaky. Figure 9.1 shows a hypothetical model
of a leaky BBB that contributes to the entry of mercury into a neonatal or a
young child’s brain. Is there any evidence that the ASD child suffers from
increased amounts of inflammatory cytokine levels and, if so, that they
have a leaky BBB?
A number of inflammatory molecules have been shown to be increased in
the brain and cerebrospinal fluid (CSF) of many ASD individuals including

Table 9.3 Mercury‐containing influenza vaccines.

AGE

AVG WT

FOR AGE

MAX ALLOWABLE

MERCURY EXPOSURE

(for avg weight at age)

MERCURY

IN FLU SHOT

FACTOR

OVER EPA

LIMITS

6 Months 7.7 kg 0.77 mcg 12.5 mcg 16.2 x

12 Months 10.5 kg 1.05 mcg 12.5 mcg 11.9 x

24 Months 12.3 kg 1.23 mcg 12.5 mcg 10.2 x

36 Months 14.5 kg 1.45 mcg 25 mcg 17.2 x

4 Years 16.3 kg 1.63 mcg 25 mcg 15.3 x

6 Years 20.5 kg 2.05 mcg 25 mcg 12.2 x

Fetus 1.0 kg 0.01 mcg 25 mcg 2,500 x

Adult 70 kg 7.0 mcg 25 mcg 3.5 x

Mercury‐containing influenza vaccinations in early childhood will exceed EPA guidelines for
maximum daily mercury exposure [based on EPA reference dose (0.1 mcg/kg) example for
28‐week gestation].