A sticky situation. New data show that using methylmercury as a
reference for calculating risk from ethylmercury in vaccines may be
fraught with problems.
During their first two years, children in the United States may receive
more than 20 routine vaccinations. The rise in childhood autism has
sparked concerns that thimerosal-derived ethylmercury may be at least
partly to blame for some of these cases—concerns that are largely
driven by awareness of methylmercury’s neurotoxicity. Beginning in 1999
thimerosal-free versions of routine vaccines for children under age 6
started becoming available. However, as of winter 2005, the flu vaccine
still contained thimerosal, and the preservative continues to be used
in vaccines in other countries.
In the current study, researchers assigned 41 newborn monkeys to one of
three exposure groups. Seventeen of the monkeys were injected with
vaccines spiked with thimerosal for a total mercury dose of 20
micrograms per kilogram (µg/kg) at ages 0, 7, 14, and 21 days,
mimicking the typical schedule of vaccines for human infants. At the same ages, another 17 monkeys received 20 µg/kg methylmercury by stomach tube to mimic typical methylmercury exposure. A third group of 7 monkeys served as unexposed controls.
The researchers drew blood from all monkeys prior to any exposure and
at other points prior to sacrifice, which occurred 2, 4, 7, or 28 days
after the last dosing on day 21. Total mercury concentrations were
measured in blood samples, and total and inorganic mercury
concentrations were measured in brain samples. Organic mercury
concentrations were calculated from those values.
The initial absorption rate and tissue distribution of mercury was
similar in both exposed groups. However, total mercury progressively
accumulated in the blood of methylmercury-exposed monkeys and remained detectable 28 days after the last dose. Among thimerosal-exposed monkeys, total mercury in blood declined rapidly between doses, and the researchers estimated clearance to be 5.4-fold higher than in the
methylmercury group. In the thimerosal group, the half-life of total
mercury in blood was 6.9 days, compared to 19.1 days for the
methylmercury group.
Brain concentrations of total mercury were approximately 3-4 times
lower in the thimerosal group than in the methylmercury group, and total
mercury cleared more rapidly in the thimerosal group (with a half-life
of 24.2 days versus 59.5 days). However, the proportion of inorganic
mercury in the brain was much higher in the thimerosal group (21-86% of
total mercury) compared to the methylmercury group (6-10%). Brain
concentrations of inorganic mercury were approximately twice as high in
the thimerosal group compared to the methylmercury group. Inorganic
mercury remains in the brain much longer than organic mercury, with an
estimated half-life of more than a year. It’s not currently known
whether inorganic mercury presents any risk to the developing brain.
Given these findings, the researchers caution that risk assessments for
thimerosal based on studies using blood mercury measurements may not be valid, depending on the design of the study. Further, the observed
differences in distribution and breakdown of mercury compounds between
exposed groups indicate that methylmercury is not a suitable model for
thimerosal toxicity.
The researchers emphasize, however, that the risks associated with
low-level exposures to inorganic mercury in the developing brain are
unknown, and they describe other research linking persistent inorganic
mercury exposure with increased activation of microglia in the brain,
an effect recently reported in children with autism. They recommend
further research focused specifically on the biotransformation of thimerosal and its neurotoxic potential.
Link to original abstract:
http://ehp.niehs.nih.gov/docs/2005/7712/abstract.html
Re: Thimerosal and Animal Brains
I hate to venture an opinon on something I know nothing about, but…
I went their site, and did not find anything of much substance about just what it is they do. They made some vague claims about what the conditions they treat are (which I cannot dispute simply because I am not really sure what it is they were saying). One claim that I found to be rather questionable is that they seem to say that you can run their program at home in less than an hour a day (don’t know how this would jive with dyslexia programs or non-medical treatment for ADD, but there is absolutely no credible evidence that any therapy for autism will work that is less intensive than 30 hours per week.)
I will say that I had a “red flag” moment when I clicked on their links titled “case studies” and found not one case study but ust more vague mumbo-jumbo and a tetimonial. I am sorry, but a case study is just a bit more substantive than that, and preferable would contain a citation of it’s publication in some peer-reviewed journal.
I wonder how much this “dr.” charges for her work?
Re: Thimerosal and Animal Brains
Dad, this was taken from Seattle’s Child August 2005 issue: If you go to a HANDLE practitioner expect to spend most of the day on your first appointment. You’ll have a two-hour evaluation in the morning, and you’ll return a couple of hours later for a two- hour presentation of results and activities. You’ll also receive a videotape of the session. About a week later, you return for another two-hour appointment, in which your program is further fine tuned.It is a home based program ; the acivities take no longer than a half hour per day, and may be spread out throughout the day. At the HANDLE Instiute International.LLC, the cost is 1,800 for the entire package; however, it is more expensive if you want to see Judith Bluestone (and more difficult to get an appointment-these days she is usually only seeing clients with the most complex needs.) Peg the lady that wrote this article used to be our reading tutor she used the “Spalding” program and my child did get up to a third grade reading level, but then progress stopped and I started the “Barton” reading program and am helping her read by myself instead. Peg is a receptionist at the clinic,but is going into an internship there so she can help kids, as some (which probably included mine) have something else going on beyond their difficulty decoding words. She is amazed at the progress kids make with the HANDLE intervention. She told me of a boy who didn’t confuse the b-d after his HANDLE intervention without using tricks.My husband is skeptical as well as I, as I see she could have used the exercizes they have when she was younger,but am wondering if they will really help now that she is older with residual language problems.
Dad,
I haven’t visited ldonline for quite a while so I’m out of the flow of the conversation. However I always remember your posts and your concerns about autism.
Are you familiar with the Handle Institute (www.handle.org), the work of Judith Bluestone, and her most recent book, The Fabric of Autism?
I think she has a lot to offer… I’d like to know what you think.
Linda W.