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Tuesday, February 28, 2012

Autism and Toxins. Yawn.

I spent a frustrating day yesterday arguing with other mums online (yep stupid, I know) about the science behind autism treatments, or lack thereof. One mum is convinced she poisoned her son and now he is on some fangdangle bio medical diet and is 'detoxing' from all the poisons in his system he is on the road to recovery. Gah!

Then I caught up on one of my favourite autism blogs and voila, a comprehensive look at some recent studies relating to heavy metal levels in autistics.


  1. Hello,
    I just wanted to say that I was very touched by your site. We don't live with autism, but two of my sons have Sensory Integration Disorder. They exhibit autistic like behaviors with certain "triggers" (light, noise..)
    I just wanted to say that you are in my thoughts and prayers.
    Blessings to you and your beautiful family,

  2. Michelle, thank you so much for stopping by and your kind words. Sensory issues are some of the biggest challenges to manage, and I feel for your children. It's a tough world to navigate when your brain is so exquisitely tuned in.
    I hope you'll stop by again.
    take care.

  3. I'm not sure that a yawn in the appropriate response to this subject. This is a very complex subject subject that has a lot of little nuances that you have to be careful of.

    For example, as on comment by RAJ on the LBRB site so nicely points out, there can be a large difference between groups when it comes to responses to environmental influences. Or in other words, an exposure level that is completely harmless to one group might be dangerous to another.

    So with any study on the subject you have to be very careful about exactly what is being measured, exactly what it represents, and whether it would be able to show you what you are looking for.

    Any study that measures current exposure only (i.e. levels in blood or urine) or even a limited historical exposure (i.e. hair, teeth) is not going to tell the whole story about a possible relationship. Nor will any study that simply tries to establish a relationship between measurable levels and an autism diagnosis.

    I'm not trying to suggest that there is some relationship between heavy metal exposure and autism, but you have to be very careful that the studies actually support the conclusion that there is no relationship. The studies listed on LBRB - especially the most recent one - don't all necessarily meet this threshold.

  4. Thanks for your thoughts MJ but I'm sticking with the yawn. I spend enough time following curent research and listening to 'experts' talk on the topic of recent autism research to have a fair understanding of what science tells us about autisms. Note my use of plural. Yes there are many autisms each with their own aetiology and we have a long way to go to unpack their causes. Furthermore environmental factors are still being explored as there seems at least some autisms lead to environmental sensitivities. All that aside, the parents who believe their child's autism is a direct consequence of toxin or certain food exposure and therefore happily expose their kids to experimental treatments, useless homeopathy, risky chiropractic manipulations and so on, yet are not open to what science tells us about autism most likely developing in the second semester of pregnancy. And that currently over 100 genes are implicated in the development of ASDs which is why what we are discussing s so complex. The interplay of these genes are so variable.
    So yes I yawn when parents supported by naturopaths, homeopaths, chiropractors and anti vaccine advocates refuse to accept that autism is a neurological condition that is far beyond the understanding of alternative quackery.

  5. I'm not quite sure which experts you are listening to as almost all of them that I am aware of now acknowledge that the environment plans a large role in the development of autism.

    Yes, there may be many genes that have a possible association with autism but there are very few - if any - that have a demonstrated, causal relationship. The only two that spring to mind that have been demonstrated to leap to autism are the mutations behinds Rett's and (some of the time) Fragile-X. The other mutations are mere possible associations in an extremely small portion of cases (much less than 1%).

    I am sure you know the line, correlation is not causation. You can't take a rare association that is found in an extremely limited subset and say that it has been "implicated" in autism. There is a good chance that these rare mutations are just random. And since most of these associations have not been replicated in other populations, it is likely that these associations are just random chance.

    Combine that with the the latest sibling and twin studies of autism that show that autism isn't quite as "genetic" as thought and you can see why the science of autism is rapidly moving towards a shared environmental/genetic model of autism.

    And that takes us into the world of epigentics where the exact relationship between genetics and environment gets a little murky. It also takes us to a world were it is much harder to establish a temporal correlation because the environmental exposure that causes the epigenetic change can be in earlier generations.

    As in a study between that looks for an assoication between circulating levels of heavy metals and autism isn't particularly relevent because it might not have been the child's exposure to substance that did the damage. It might have been the parent's exposure while they were younger or it could possibly have been an exposure during pregnancy. Or it could have been a one time exposure at the exact wrong time during post-natal development that pushed some process out of balance.

    None of these models calls for a continuing exposure that would show up in blood or urine, and only some of the models would imply a difference in the hair. But then again, if you look at a 16 year old's hair it won't be able to show exposures that happened 15 years ago.

    I really don't want to get into a long conversation about this but I would suggest keeping an open mind in this subject. There is certainly some quackery here but there is also some truth here as well and it is hard to separate the two.

    Autism is one of those things were it is difficult to fully grasp parts of it unless you have lived it or seen it first hand. If is very easy to look at another parent and think they are being ridiculous because "science" says that they are wrong and their experiences don't mesh well with yours.

    It is much harder to put yourself in the place of the other parent and understand exactly why they think what they do. It is even harder to acknowledge that they might be right about their particular circumstances - even though you think that "science" says otherwise.

  6. You ask which experts I'm referring to, a couple of weeks ago I went to a presentation by Dr Andrew Whitehouse (
    And while yes he acknowledged the continued exploration of possible environmental causes he stated the genetics are becoming clearer all the time. I also attended the Asia Pacific Autism Conference here in Perth last year at which several interesting genetic research papers were given and I followed with interest the papers that came out at IMFAR last year. So I'm reading what would be considered reputable research. There's also the autism research blogs. Then there's the papers I read as part of my Masters in Autism Studies.

    Can I add I do not think parents who turn to alternative treatments are ridiculous, I actually know many parents who embrace a bio medical model. I think desperation is a major driver.
    I understand your reticence to get into a long conversation about this so I will leave it there, just wanted to give you some ideas of where I am sourcing my info. And I do appreciate the points you are making.


  8. The first question that study begs is whether having a mother or father in common made a difference in the outcome.

    The second question would be whether the full/half sibling rates were in line with other recent estimates.

    The third question would be how many of the parents moved into a new area before having the subsequent child.

    The last question would be whether there was a difference between the full/half siblings in birth order - was it an earlier or later child that had the autism.

    All of these factors could potentially explain the outcome without involving genetics. But regardless, it does look like it is worth getting the full test and reading it.

  9. Sorry, one more comment about the sibling study you referenced. I finally got the text and a chance to read it and can fill in some of the blanks from my last comment.

    First of all, this really isn't a peer-reviewed study but rather a Letter To the Editor so there is very little actual data included in the letter and the methods used aren't described in any depth.

    But ....
    First, there was a significant difference between having a mother or father in common. Maternal half siblings had a reoccurance rate of 0.05 while paternal siblings had a rate of 0.00. The paternal sample was 1/10 the size of the maternal one but still large enough to expect some reoccurance.

    Two, the rate found for full siblings (9.5 percent) was lower than more recent, larger estimates (18.7 percent).

    Three, the data can't address it and it is acknowledged as a weakness of the data. But they include yet another unpublished small data set from another source that might show it isn't a factor.

    Four, isn't really covered.