I just love being right. So anytime science vindicates me or my positions I will echo the findings. I recently posted about immunizations and the myths surrounding them. Years ago, some science journal decided to publish some poorly constructed study about autism and Thimerosal, an antiseptic additive used in vaccines to prevent bacterial contamination.
Some hack in the science world noticed that autism rates were increasing dramatically and he felt that this had to be related to immunizations, since our immunization rates have also gone up dramatically over the past several decades. His study was published in a British science journal and before too long it caught on in the US. Add a few celebrities and political names, ie RFK Jr, and soon the hysteria set in. Parents began withdrawing their children from immunization programs, and refusing very important vaccines out of fear of autism. Lawsuits and rumors of lawsuits began to build. The vaccine manufacturers began to panic.
Keep in mind that there have been many studies on this and some of those predated the study that induced all of this panic. Those studies showed thimerosal to be safe and not linked in any way to neurologic disease, including autism. Of course, science has never stopped people from taking drastic, irrational action (anyone remember what happended with DDT? How many people die every year from malaria since we banned it on bad science?). So the fear of lawsuits basically led the vaccine manufacturers to remove thimerosal from their vaccines in 1999 despite the lack of scientific evidence supporting such action. As a sidenote, this action alone could potentially be harmful since the reason for having thimerosal in the vaccine came about after several children died from a staph infection they received from a contaminated vial of vaccine. This didn't happen once the thimerosal was added. Granted, there are other ways to keep the vaccine clean, but still this was something that didn't have to be done given the actual evidence.
Anyway, the California Dept of Developmental Services has just completed a study that basically blows RFK Jr's cause completely out of the water and (hopefully) ends the discussion altogether. They've been tracking autism rates with close scrutiny since 1999 to see if there would be any impact from withdrawing the thimerosal. This is classic epidemiology. If a disease is caused by a particular agent, then removing that agent will lead to a decrease in the disease rate. So what did they find in California? Interestingly, the rate of autism has actually INCREASED since we stopped giving our children thimerosal in their vaccines.
Does this mean thimerosal provided an element of protection from autism? Of course not. But it does confirm the generally agreed upon theory regarding the increasing rates of autism. Basically, autism has increased because we have gotten better at screening for it, recognizing it, and diagnosing it properly. In the past, these children were simply labelled as "mentally retarded" because we didn't know much about autism. Now, we are diagnosing them appropriately. Plus, we have developed some screening tools to pick up on the diagnosis at younger and younger ages, and we are doing better at instructing parents on what signs to look for. So technically autism the disease is not increasing in frequency, but autism the diagnosis is. Make sense?
It is my sincere hope that this new study ends the discussion completely, and parents stop endangering their children with silly myths. But, somehow, I wouldn't be surprised if nothing changed.
6 comments:
You summarized with "Make sense?"
Yes, a great deal of sense. Thimerosal has been around a long time; used in a number of applications; it apparently does not affect physiology as severely as some Hg compounds. Unfortunately, diagnosis of autism
frequently occurs about the time of infant vaccinations and it is natural for parents to associcate
some connection..especially as there seems no other red flag cause. I agree that diagnosis
historically would have been any number of other 'names...in fact, one wonders if the current Alzheimer's epidemic similarly
codifies the older 'senility' commonly associated with advanced
aging? Regarding the merits of DDT, it seems to possess a long half-life, say compared to the organo-phosphates..probably why it was effective against the mosquito
life cycle...and why like dioxins and other stable chlorocarbons it is of concern to health agencies.
I think that another reason there are more diagnosis of autism is because there is less acceptance of difference in our society. If we or our children are different, we have to find out why.
50 years ago, people would have said, "that kid is just a little bit different". He may or may not have found a way to overcome his differences. My oldest has some interesting tendencies. He, however, is just highly gifted. It does cause him to be a bit different from his age peers and when he was younger (thanks to all the hype about vaccines causing autism), we were concerned that he may have mild autism. We now know that he doesn't.
A question, are we seeing increasing rates of autism across the spectrum or is it mostly in the mild areas?
Doctor,
I am not a proponent of junk science but are you saying that the studies linking DDT to, inter alia, drastically weakened egg shells of raptors at the top of the food chain, were junk science?
My understanding is that thousands of deaths from malaria, particularly in Africa, could be averted by allowing DDT to be sprayed on the walls in the interior of homes and obviously interior use limits DDT's environmmentla impact.
Regards.
Kristina, by far the majority of cases are in the mild category and are improvements in diagnosis are picking up these cases, thus causing the perceived increased "rate" of autism.
Loop, I am not at all saying that DDT and raptor egg shells is junk science. Although there is some dispute about it. You can decide for yourself if protecting some birds is worth the loss of life. For me it's a no brainer.
Much of the panic with DDT was based on false assumptions, ie, if DDT harms a birds egg shell then it must be harmful to humans.
And I believe you are correct in what you said about the interior use of DDT. The problem is that since the US banned DDT there are no industries that produce it. Plus, our financial influence in Africa discourages many nations from using it. Meanwhile, malaria has increased at alarming rates across Africa and Asia.
I find it interesting how some people weep for Darfur and demand action, but won't take any effort to get DDT back into Africa. Doesn't make sense to me.
Some mosquitos already are developing ddt resistance, for example:
http://www3.interscience.wiley.com/cgi-bin/abstract/112601827/ABSTRACT?CRETRY=1&SRETRY=0ddt-resistance.
..one logical approach is to target the parasite plasmodium species, for example:
http://microbiologybytes.wordpress.com/2006/10/09/giving-malaria-the-slip/
...dependence on a single chemical very often gradually fails due to various adaptations by the target pathogen, as exemplified by the
comeback of tuberculosis, see:
http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=35815
..of course the medical community is well aware of those factors, and I believe mostly supports the proper use of DDT in areas where malaria is endemic; see:
http://www.un.org/apps/news/story.asp?NewsID=19855&Cr=malaria&Cr1
Doctor,
Let us leave Africa for the nonce where we agree that some use of DDT would be beneficial, although bb-idaho has a goos point about developing DDT resistant mosquitos.
Assuming that the potential negartive effects of DDT were exagerrated in this country what was the harm? It seems as if we have saved our natiuon symbol form extinction and it alkso seems to me that in all likelihood the raptors were not the sole beneficiaries.
This provides, perhaps, an example of unitended good consequences and is reason why I tend to look askance at people who decry global warming as a hoax or junk science or whatever. It is entirely possible if not probable that changing behavor may result in things like conservation or technological discoveries that would not otherwise be made.
Look at a list of all the technology that has come from our efforts during wartime.
Not everything that bucks the status quo will be beneficial but certainly some things will be.
Regards.
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