Oct 21 2009

Another Study Showing Lack of Correlation Between Mercury and Autism

A new study published online in Environmental Health Perspectives shows no correlation between blood mercury levels in 2-5 year old children and autism or developmental delay. This study adds to the growing evidence that environmental exposure to mercury, from any source, is not a risk factor for autism.

The study looked at 452 children aged 2-5 (which is a robust sample) with either autism spectrum disorder (ASD), other developmental delay (DD), or typically developed (TD). They found that children with ASD and DD had lower levels of blood mercury than TD controls. They further found that ASD and DD children tended to eat less fish, and as fish is by far the most significant source of mercury exposure, this explains their lower levels.

The researchers then adjusted for reported exposure to fish as well as other known sources of mercury and found that the adjusted level of mercury were the same for all groups. The levels were also similar to established national norms, meaning that the population being studied and the methods used are likely representative.

What this means is that, at least during the ages of 2-5, kids with ASD do not have higher blood levels of mercury than TD controls. It further indicates that their metabolism of mercury is not likely to be different because their adjusted levels were the same. If ASD children had a problem with eliminating mercury, as has been proposed by vaccine-autism link proponents, then we would expect that they would have a higher level of mercury for a given exposure.

The study authors are open and, I feel, fair about the strengths and weaknesses of this study. They do not have information from pre-natal and early post-natal mercury exposure or levels, so their study cannot rule out an association there.

They also do not have data on mercury levels in other tissues. Vaccine-autism link proponents claim that some children with ASD tend to store more mercury in their brains, so their higher mercury burden is not reflected in their blood levels. However, without evidence this is just special pleading. Further, there is evidence to suggest that blood levels correlate well with mercury levels in other tissues, including the brain. And further still, this study suggests that children with ASD handle mercury similarly to TD controls, as their adjusted blood levels were the same.

Of course, this one study cannot disprove a link between vaccines and autism. But this adds to the growing body of evidence for a lack of a correlation. All studies looking at exposure to thimerosal, a mercury-containing preservative in some vaccines, and autism or other neurological disorders has shown no correlation. And most significantly, when thimerosal was removed from the vaccine schedule in the US (it now remains only in some optional vaccines) there was no corresponding change in the rate of autism diagnoses. (See here for a thorough review of relevant studies.)

The utter failure of the vaccine-autism hypothesis has led some in the anti-vaccine crowd to broaden their claim to a more vague reference to “toxins” or to “environmental factors.” This study shows a lack of correlation between autism and mercury from any source.

Further, the scientific evidence is moving steadily in the direction of showing that ASD is a collection of genetic disorders, or at least has strong genetic correlates.

None of this, unfortunately, will stop the anti-vaccine movement from using the specter of ASD to scare parents away from vaccines.

17 responses so far

17 thoughts on “Another Study Showing Lack of Correlation Between Mercury and Autism”

  1. superdave says:

    You can tell that this is a good study from the fact that the post about it on the AoA website didn’t even contain a link to the article or abstract, and that their tear down of the study basically consisted of discussing results from different studies.
    The real shame is that the AoA is dismissive of this study for no real reason. Instead of trying to glean meaningful information from what the study says, they insist on interpreting what the study doesn’t say. They could easily have taken the position that this study shows that if the mercury avenue is pursued, research should focus on infant and neonates. However, they are so dismissive they don’t even let themselves make even this relatively minor concession in the face of new data. Instead they claim that autistic children are more sensitive to mercury. These people always claim they want new research but this is what they do with it?

  2. That is a key feature of denialism – focusing on what the evidence does not show, as if that negates what it does show. You can take each piece of evidence in isolation and dismiss it, because all by itself it does not prove or disprove a theory. But when you put it all together, it does give us a pretty consistent picture.

  3. daedalus2u says:

    What I like about this study is that they did a sensitivity analysis on sources of mercury they found in the children which showed that the amount of mercury in vaccines was tiny compared to mercury in the diet and mercury in earwax removers and nasal sprays.

    In order of importance to mercury levels it was any fish, ocean fish, tuna fish, fresh water fish, ear wax removers and nasal sprays, dental amalgams, and last (and the least of what they considered) thimerosal in vaccines.

    Not surprisingly, variations in the largest sources of mercury had the largest effects on levels of mercury in the children and the smallest source considered, thimerosal had a negligible effect.

  4. Watcher says:

    They further found that ASD and DD children tended to eat less fish, and as fish is by far the most significant source of mercury exposure, this explains their lower levels.

    See? What this shows is that there bodies telling them to not eat any fish because of all the mercury they can’t process!!1!

    Sarcastic statements just aren’t the same without a good smiley 🙁

    Anyways, it’s nice to see more data on this. Science is “quietly” amassing a bit of data mountain when it comes to this. I have a feeling that in 10 years we may be able to put the keibash on this autism/vaccine fear mongering. I’m not saying that anti-vaxxers won’t still be around, just that they’ll have moved onto something else.

  5. Mark Entel says:

    Here is one more media outlet getting it right — Wired.com


    this feature includes comment from the editors re: the fact-checking & editing process and how that gave them the confidence to run a piece on vaccine safety despite the controversy.

    Interesting & creative example of how responsible journalism can tackle an issue surrounded by a misinformation dust cloud as vaccine safety is,

  6. Mark Entel says:

    Sorry, here is the link to the article proper, the above link describes the process behind the story —


  7. mindme says:

    Wow. AoA comments on the study but doesn’t actually post a link to it? Bahahaha. Sounds like the creationists sites that never actually post a link to what they’re criticizing. I’m sure the telling similarity there would completely escape the AoA folks.

  8. webbdj says:

    Possibly this has been raised before, but given the nature of these posts, the Google Ads in the side bar are often both ironic and rather depressing. Today we have one company


    offering to remove mercury from the body. I quote from their web site:

    “How Did I Get Heavy Metals (Mercury and Lead) In My Body?

    There are several possible ways heavy metals got into your body. Below each of the more common exposures will be discussed. Remember there are no safe levels for heavy metals. Chelation of toxic heavy metals with DMSA is well documented in the scientific literature. There are several other chelation agents but DMSA so far as (sic) been proven to be the safest and most effective.

    There are 4 main sources of mercury poisoning:

    1. In Vitro (sic), passed from mother to baby

    2. Vaccinations

    3. Dental Amalgams or ‘Silver Fillings’

    4. Contraception Pills and Contact Lense Solution

    In Vitro

    A mother with mercury in her body will pass it into her baby. The level of mercury in the tissue of the fetus, newborn, and young children is directly proportional to the number of silver fillings in the mother’s mouth.


    Vaccinations are the #1 mercury exposure in infants, and the #2 exposure in adults.

    *25% of vaccines today still contain mercury.

    *Flu shots still contain mercury.

    *When mercury is removed from flu shots, it is replaced with other heavy metals such as aluminum and formaldehyde.”

    It goes on. You notice there is no mention of eating fish here, mothers are made of glass and apparently formaldehyde is a heavy metal.

    The second company is even more worrying


    They are promoting stem cell treatments for epilepsy, multiple sclerosis, autism and cerebral palsy and have “testimonials” to the effectiveness of the treatment.

  9. provaxmom says:

    I belong to another parenting board for atheists and agnostics, and quite frequently our ads are for xian organizations. It’s just the bots doing the searching, they can’t tell the context in which the word is being used. The bots just search for key terms and then display ads ‘accordingly.’ If they only knew how their advertising dollars were being wasted.

    I really enjoyed reading this most recent study on mercury. I also want to thank whoever posted the Wired articles, but I found those to be disheartening. From a personal perspective, reading articles like the one in Wired and the fair profile of Dr. Offit in Philadelphia magazine this summer, it was starting to feel as if the tide was turning. Like the mainstream media was finally giving us a fair shake instead of all the “Are Vax Dangerous?” articles. But to hear that the non-vaxing rate among parents has actually risen to well over 2%, that’s the disheartening part.

    As a mom of two small children, it infuriates me that they put my kids in danger. And one of my boys is autistic, so it makes my head explode to see attention and resources drawn to such nonsense. To my knowledge, there are no fringe groups within the breast cancer community, or within the juvenile diabetes community drawing research dollars away from the real cause and treatment. If there are such groups, they certainly aren’t the media darlings that the anti-vax people are.

    With that recent study showing 65% of autistic individuals have the same gene abnormality, and another estimated 5-10% of autistic individuals have the same genetic abnormality my son has (dup 15Q syndrome). That means we can account for genetic abnormalities for up to 75% of all autistic individuals. Our focus needs to be on gene therapy, not vaccinations.

  10. Studies, lots of percentages and letters in front of and behind peoples names that have opinions. I’ve always thought; to find the right answers, you must first discover the right questions. I must admit, I had a laugh when you describe fear mongering on behalf of anti-vaccine folks, but ignore the fear mongering of the pro-vaccine folks; “If you don’t get the flu shot you can die.” Looks like it goes both ways to me.

    Yet, at the University of Calgary, the Dept. of Physiology and Biophysics Faculty of Medicine did a film on “How Mercury Causes Brain Neuron Degeneration”. They showed that mercury vapour inhalation by animals produced a molecular lesion in brain protein metabolism similiar to those found in 80% of altzheimers diseased brains. I guess that’s okay though cause it’s not autism.

    Q: Were the scientists/doctors that did your study the same ones governments have used to say cannabis was a gateway drug, or more deadly than herion and cocaine?

    Yeah, studies can be made to say whatever the governments want them to say. Maybe you can tell me about this “excited delirium” folks in police custody keep dying from, cause it’s not recognized by the Canadian or American Medical Associations or the Brain Shrink Associations either. But the people that make the tasers have lots of studies about it.

    Here’s another FACT that worries the anti-vaccine folk: Baxter Pharmaceutical has been caught, red-handed, in spreading a live, genetically engineered H5N1 Bird flu vaccine as a lethal biological weapon all over the world, destined to be used for human vaccinations. This happened just a few months ago. Only by sheer luck, a Czech laboratory decided to test the vaccine on a dozen ferrets, which all died in days. Then they said; “Ooops, must have been a mistake.”

    Now it may seem like none of this has anything to do with your study and yet it does. You admit; “They do not have information from pre-natal and early post-natal mercury exposure or levels, so their study cannot rule out an association there.” Yet discount it. They also do not have data on mercury levels in other tissues…like the brain. Now is it that they really don’t have that info or didn’t release it with the study.

    What about all the independant studies over the years by dcotors that have stated that flu vaccines are a hoax, and can actually decrease your natural immunities. Afterall, most everyone I have known to get the flu shot has also gotten the flu. Whereas I’m 43, have NEVER had a flu shot and have also NEVER had the flu. Even after spending the last number of years living/travelling as a homeless man(My own research).

    The reality is governments the world over (Canada, U.S included) have been caught conducting questionable and unethical research or experiments on their own people.
    Let’s not forget all those warm blankets the natives were given contaminated with small pox.

    As a result, people do not distrust their governments without reason. Yet the government does use these FAKE reasons to supress, enslave and murder the less fortunate. Much like Massachusetts, already trying to pass a law for forced vaccines, forced quarentines, martial law, lethal force…that kin of thing.
    Or when the Canadian government sent body bags to native reservations instead of hand sanitizer and medication.

    There has been a long history of the Elite finding, funding, and fudging the undesirables our of everything including their lives.
    Study that.

    your humble servant,
    ancient clown

  11. provaxmom says:

    [[I must admit, I had a laugh when you describe fear mongering on behalf of anti-vaccine folks, but ignore the fear mongering of the pro-vaccine folks; “If you don’t get the flu shot you can die.” Looks like it goes both ways to me.]]

    This is one of the most frustrating discussion points I run into. What the anti-vax people don’t seem to want to comprehend, is that unlike the fear of developing autism or some neurological disorder from the vax–which has never been proven, the fear of developing the vax preventable diseases is real. And they are on the rise.

    If there ever comes a point in time where studies prove that vax cause autism, I will eat crow and plenty of it. But at this point in time, there is no evidence to support it.

    The fact is, thousands of kids do die from the flu each year. Thousands of kids do not develop autism from vaccines every year. Can you see the difference?

  12. kim spencer says:


    Find ONE study that says kindergarten boosters and a flu shot in one day are safe.

    find it. bring it on.

  13. daedalus2u says:

    kim spencer, find one study that says that a single week of kindergarten is safe. A week? How about a single study that shows that a single day of kindergarten is safe?

    find it. bring it on.

  14. kim spencer says:


    i’m not sure, but i really don’t think comparing a medical procedure to time spent in kindergarten really have anything to do with each other.

    maybe you were drunk or something when you thought this up?

  15. tmac57 says:

    kim spenser- “i’m not sure, but i really don’t think comparing a medical procedure to time spent in kindergarten really have anything to do with each other.”
    I think it is a fair comparison in that we should weigh the benefits versus the harm in ALL of our daily actions. Children are sometimes at risk in kindergarten and day care facilities. Parents have to weigh the likelihood that their children might be harmed against the benefit of kindergarten. My guess is that probably more children are harmed in kindergarten than by vaccines, but that wouldn’t mean that kindergarten is NOT relatively safe, only that it is not ABSOLUTELY safe, just as virtually no beneficial action that we take is completely without some remote risk.

  16. daedalus2u says:

    kim spencer is obviously a kindergarten shill. Bought and paid for by the kindergarten teachers’ lobby. Never heard of the kindergarten teachers’ lobby? Ha! Just goes to show how powerful they are that they keep their agenda so secret and so hidden that no one even knows the organization exists. The kindergarten teachers lobby is so powerful and secretive that they keep their existence hidden even from Google. “The kindergarten teachers lobby” produces no hits on Google.

    Big kindergarten has access to virtually everyone during their formative years for multiple hours every day! What better way to manipulate the nation that to mold its impressionable youth by plying them with milk and cookies, playing games with them, and then lulling them to sleep with stories.

    Of course there are no studies showing that kindergarten is safe. If Big Kindergarten gets its way there never will be!

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