EXCELLENT, thanks! That's going in FAQ's. I found this, recently, on Bromides and Auditory response. The reason that I was delving into this is because I have noticed that when I eat something that possibly contains bromide, I'll feel it in my ears, kind of an atmospheric pressure sort of thing. Anyone else experience that?


http://www.credocluster.info/docs/newsletter/credonews6.pdf



Disruption of the thyroid hormone system by brominated flame retardants

From the studies with TBBPA and HBCD it appeared
that there were some marked effects on the thyroid
hormone system.
In the study with TBBPA, the biologically most relevant
effect was probably the increase in latencies of
auditory responses (tested with brainstem auditory
evoked potentials (BAEP)), in particular, in the lower
frequency range (figure 1). This effect is, most likely,
related to impairment of the development of the
upper (apical) part of the cochlea, the spiral cavity of the inner
ear. TBBPA related changes in plasma thyroid hormone levels,
including a decrease of thyroxine (TT4), and an increase
of triiodothyronin (TT3; only females), are likely behind the
impaired auditory responses, because it is known that disturbances
of thyroid hormone levels in the neonatal peiod can
result in similar effects. A tentative explanation for these
results is that TBBPA competes with thyroid hormones on
thyroid hormone plasma binding proteins (mainly TTR in the
rat), thus releasing these hormones for metabolism. This
explanation is plausible in view of data from the in vitro
reporter assays, showing a very potent competition of
TBBPA with human TTR. The benchmark dose (BMD-L) at
the lower confidence level for this effect was in the range of
2 to 28 mg TBBPA / kg body weight per day at specific effect
levels for each end point. The 28-day study with HBCD
showed consistent effects on the thyroid hormone axis,
including decreased T4, increased pituitary and TSH in this
gland (by immunostaining), and increased thyroid weight and
activation (histopathology, figure 2) mainly in female rats.
Some further effects can be understood as secondary to the
disruption of the TH axis: increased plasma cholesterol,
decreased plasma glucose, and increased bone density
measured in collaborative action with the BONETOX project).
In contrast to TBBPA, the effects with HBCD are probably
indirect, through activation of metabolising enzymes in the
liver (e.g. T4 glucuronyl transferase), also indicated by the
increased liver weight in females. Benchmark doses at the
lower confidence level for these effects were in the range of
20 to 90 mg HBCD /kg bw, for each endpoint at a specific
effect level (range 5 to 20%).
It is thus evident that brominated flame retardants can disrupt
the thyroid hormone system in a whole organism. These
and other results from these studies will now be entered in
the theme “integrated risk assessment” of the project,
where they will be compared with exposure levels of these
compounds, which were measured in humans (plasma and
milk), human food, and wildlife. In this way, it should be
possible to determine the relevance of the findings in the toxicity
studies for health of humans and other mammals.