Human Journey

Zeroing in on the Causes of Autism

By Brita Belli

Autism research is finally turning its focus to the impact of environmental toxins and finding that exposures to a number of common chemicals—particularly during pregnancy—plays a major role.

Officially, the number of kids with autism in the U.S. is now one in 88, according to the latest numbers from the Centers for Disease Control and Prevention.

But more recent research suggests that when universal screening for autism—a disorder characterized by inhibited social functioning and repetitive behavior—is done, that incidence may be much higher.

And last year, the California Autism Twins Study, which assessed 192 twin pairs born between 1984 and 2004, found that heritability, or genetics, accounted for 38 percent of cases of Autism Spectrum Disorder, while “a shared twin environmental component” accounted for 58 percent of cases.

The idea that toxins—including heavy metals like mercury, pesticides, flame retardants, and chemicals in plastic—along with certain drugs approved during pregnancy and childbirth are directly contributing to these rising autism rates (along with, it should be noted, a host of childhood disorders and diseases on the rise), is the subject of my just-released book The Autism Puzzle: Connecting the Dots Between Environmental Toxins and Rising Autism Rates. In it, I take a close look at the role played by mercury and heavy metals, not in vaccines but in fish and in urban environments.

A 2006 study in Texas, for instance, found that for every 1,000 pounds of environmentally released mercury, there was a 61 percent increase in the rate of autism. Families living in urban environments are particularly vulnerable to toxic assaults—from outdated buildings with peeling lead paint, which is known to cause neurological damage; to cockroach treatments such as the now banned chlorpyrifos, which has been tied to pervasive developmental disorder (including autism) in children exposed in utero; to air pollution.

Often, families living in these conditions are not as able to recognize the signs of autism, and they are more likely to receive a delayed diagnosis or mistaken diagnosis. One study found that among children on Medicaid, those who had been on the program for more than a year were 3.4 times as likely to receive a diagnosis other than autism versus those who had been on Medicaid for less than a year.

At the same time, many of the chemical exposures that seem to act with genetic susceptibility to give rise to autism are nearly ubiquitous across the developed world. Our lax chemical regulations in the U.S., which depend on the threadbare protections of the 1976 Toxic Substances Control Act (TSCA), have exempted some 61,000 chemicals from testing for environmental or human health effects.

That means, for instance, that even when the chemical Bisphenol A (BPA) is declared by the Food and Drug Administration to be of concern for its “potential effects…on the brain, behavior, and prostate gland of fetuses, infants and children,” the agency is still unable to regulate it because it is exempted under TSCA. Both BPA—which lines most soup cans and is present on cash register receipts, and phthalates—industrial compounds that soften plastic and are found in everything from flooring to bath toys to nail polish—have been tied to autism and autism-like behaviors.

While there are steps parents can take to minimize their exposure to chemicals, from buying organic fruits and vegetables to avoiding plastic food storage containers and making their own nontoxic cleaners, it is impossible for any parent to completely steer clear of potentially harmful exposures that can come from furniture, electronics, clothing, cosmetics, or school gymnasiums, to name but a few.

The more research that unfolds connecting autism to chemical exposures, the more it becomes clear that our outdated chemical policy is posing a direct harm to the nation’s children.

Faced with similar concerns, the European Union passed the Registration, Evaluation, Authorisation and Restriction of Chemical substances (REACH) legislation in 2007, which will require all chemical manufacturers to prove the safety of their products and to replace dangerous chemicals with safer alternatives. A similar movement is at work in the U.S. with the Safe Chemicals Act, but thus far has failed to gain political momentum.

With Autism Awareness Month just concluded (April), and a host of childhood sensitivities and disorders on the rise, the time is ripe to push for chemical regulation that truly protects our most vulnerable citizens.


Brita Belli is the editor of E – The Environmental Magazine and the author of The Autism Puzzle: Connecting the Dots Between Environmental Toxins and Rising Autism Rates. She blogs at

  • Anne McElroy Dachel

    Brita Belli cautions us about heavy metals. She cites mercury first in a list of toxic exposures–but dismisses any concerns about the toxic exposure from vaccines.

    For years, experts told us that they really wasn’t more autism. All the kids with autism were merely the result of better diagnosing of a disorder that’s always been around. Autism was supposed to be solely genetic. Now suddenly people are admitting that the environment is also a factor. The one constant in this has been the continuous denials that there’s any connection to the ever-expanding vaccine schedule.

    People now are willing to look at any environmental factor–except vaccinations. They also refuse to research the endless thousands of children out there who were born healthy and were developing normally until they received certain routine vaccinations. Suddenly they got sick, lost learned skills, and regressed into autism. Doctors can’t explain this. They call it just a coincidence and they have lots of pharma-funded studies to prove it.

    Anne Dachel, Media editor: Age of Autism

  • Anne McElroy Dachel

    Why should we believe that an ever-expanding, untested, one-size-fits all vaccine schedule is fine for every child?

    Where is the study comparing fully-vaccinated and never-vaccinated children to see if never-vaccinated kids also have a one percent autism rate? THERE ISN’T ONE.

    Where is even ONE STUDY that disproves a link between vaccines and autism that isn’t connected to the vaccine industry. THERE ISN’T ONE.

    Those who deny that injecting more and more toxins into babies and small children is harming them are like those who deny they more and more pollution is affecting our climate. Where is the science showing that it’s safe to inject three live viruses into children at one time? THERE ISN’T ANY.

    Where are the studies that show that adding aluminum and mercury to vaccines is safe? THERE AREN’T ANY.

    Where is even one study on the cumulative effect of the increasing number of vaccines in the childhood schedule? THERE ISN’T ONE.

    Anne Dachel, Media editor: Age of Autism

  • […] I think National Geographic should stick to stories on the rain forest. Injected mercury is fine; we need to check out the fish. Zeroing in on the Causes of Autism HERE […]

  • Katie Wright

    Thank you Brita for a great post.
    You nailed it. Our failure to enact commonsense environmental safety measures is damaging the neurological health of a generation of children.

    So many of these toxic substances have been illegal for many years in Europe. BPAs, dangerous household cleaners, phlates and toxic vaccine adjuvants like Hg, AL, formaldehyde all have a negative effect on developing brains. This is the United States we can do better than this. We have the resources to protect our children from avoidable toxic exposures.

    I am a Mom of a child with autism. The bulk of our research $ is spent on genetics and we have gotten nowhere. We must tackle toxic environmental exposures.

  • Katie Wright

    Brita I missed the part where u state that we need to study heavy metals in seafood but not vaccines. Please see the work of Dr. Richard Deth and Dr. Laura Hewittson. Toxic substances in vaccines are unsafe and have never been studied in the combination in which the are commonly administered – as multiple vaccines.

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  • […] Zeroing in on the Causes of AutismNational GeographicBut more recent research suggests that when universal screening for autism—a disorder characterized by inhibited social functioning and repetitive behavior—is done, that incidence may be much higher. And last year, the California Autism Twins Study, … […]

  • Emily Willingham

    I can’t believe that National Geographic has highlighted this, especially after the debacle over this identical promotion over at Salon, picked up via Alternet. The comments say it all:

    I would expect more from an outlet that promotes itself as scientific.

  • Mark

    Moving away from mercury in vaccines and looking at mercury in fish and the environment? That would be a mistake. Nothing comes close to doing the damage to children than mercury in vaccines does. Here’s why;

    0.5 parts per billion (ppb) mercury = Kills human neuroblastoma cells (Parran et al., Toxicol Sci 2005; 86: 132-140).

    2 ppb mercury = U.S. EPA limit for drinking water (http://www.epa. gov/safewater/ contaminants/ index.html# mcls).

    20 ppb mercury = Neurite membrane structure destroyed (Leong et al., Neuroreport 2001; 12: 733-37).

    200 ppb mercury = level in liquid the EPA classifies as hazardous waste based on toxicity characteristics.

    500-1000 ppb mercury = level of mercury in large predator fish

    25,000 ppb mercury = Concentration of mercury in multi-dose, Hepatitis B vaccine vials, administered at birth from 1991-2001 in the U.S.

    50,000 ppb mercury = Concentration of mercury in multi-dose DTaP and Haemophilus B vaccine vials, administered 8 times in the 1990’s to children at 2, 4, 6, 12 and 18 months of age and currently “preservative” level mercury in multi-dose flu, meningococcal and tetanus vaccines. This can be confirmed by simply analyzing the multi-dose vials.

    in addition, the type of mercury used in vaccines is arguably the most toxic form of mercury. Unlike fish, injecting mercury into infants provides rapid access to the bloodstream

  • Valerie

    It’s hard to find decent science these days when the only ‘science’ that is funded is done so by chemical, agricultural, or pharmaceutical giants. Well, take your pick, they are all interchangable because they all own everything.

    But I digress. Let’s talk for a moment about my son who is on the autism spectrum, and how he is not just “a little bit eccentric” or “wouldn’t even have been diagnosed” 50 years ago. At the age of 3 to 4, he had echolalia, where he would repeat the same phrase over and over and over again. Not because he thought I didn’t hear him, but more in an OCD type fashion. And even now that he is ten, he gets easily overstimulated. He can’t have a Nintendo DS or watch TV for too long, because he will start hitting himself if something is too difficult or too funny. Maybe he’s mentally retarded? Well, no, because he’s way ahead of his age group at reading and math. So, apparently he’s not stupid. He has a speech delay, and it seems there is something wrong with his nervous system, but the how he came to be this way isn’t easily known. We ran blood tests, we thought maybe he had adrenal fatigue. Actually, that would make sense since his body can’t seem to create enough corisol to fight what causes his anxiety. That would explain why he gets overstimulated. I can’t imagine how horrible it would be to be stressed out and your body has no way of coping with it.

    I’m just trying to give anyone reading these comments a little anecdotal evidence. To this day he hasn’t been diagnosed by a doctor, they don’t actually diagnose it, since they don’t even know what it is. Autism isn’t really autism, it is “something is developmentally wrong, but we don’t know what it is, so we will refer to a psychiatric manual (the DSM-whatever volume you want to pick from)”. The more you think about it, autism is just a range of behavioral effects from some unknown cause(s).

  • Liz Ditz

    National Geographic should be ashamed of itself for promoting Belli’s unscientific work.

    A better title would be: “Exploiting Autism to Sell My Book, Which Is A Mess of Speculation to Advance My Agenda”

  • Rachel Cohen-Rottenberg

    Is there some good reason that National Geographic is running such pseudo-scientific nonsense? I can’t think of one.

  • Whiteandnerdy


    The errors in your argument really should be obvious to all by now.

    If you read the US Civil court records, the courts are so frustrated with correcting these errors year after year after….that they have even suggested the anti-vaccs were lying to get money when making these sorts of arguments.

    OTOH, if you were to check with actual toxicologists, they would point out that the post-vaccination mercury levels in infants are safe and that the mercury from vaccines is excreted in the feces.

    Strange how the anti-vaccs never post these facts…


  • Whiteandnerdy

    Ms Wright,

    It would have been helpful if you had posted that Deth’s testimony on vaccines causing autism has been ruled junk science.

    And that Hewittson was a business partner of Wakefield and has had the public humiliation of having her work on autism retracted by a journal.

    Perhaps you avoid these issues because it gets a person asking questions…

    A toxicologist would point out there are no toxins in vaccines and give you lots of examples of safety data including all the “substances” in vaccines in combination.

    But then the point is that the anti-vacc POV is rejected because they get basically every thing wrong.


    PS if you were to get your science from scientists you would learn about the significant advances in understanding the etiology and pathology of autism.

    You would also learn about promising experimental treatments for autism–including a preliminary one that appears to cure some types of autism in animal models…information that the anti-vaccs continue to censor.

  • Whiteandnerdy

    Ms Dachel,

    Most people have figured out that one should never believe Age of Autism–a site that can’t figure out that vaccines are tested for safety or even read the schedule and see that it isn’t “one-size fits all”. Etc, etc…

    But it sure does produce a lot of noise pollution.


  • Joe

    Mercury from fish, is bad! pregnant women, stay away from it for it can cause Autism. Vaccineal mercury ,is safe to inject into pregnant women, and cannot cause Autism.

    It appears the writer of this article, does not know the scientific findings to date concerning the two mercury’s. So, I will help this misinformed person that was probably paid very very handsomely. To spread this incorrect, and easily debunked misinformation. From someone, who by what she wrote. Shows, that she probably never read any of the NIH studies. And in this case, we know she has never heard of the good Dr. Burbachers baby primates studys. Studies that had found, that the Thimerosal AKA Vaccineal mercury based preservative that was so foolishly used in children’s vaccines.
    Crosses the Blood Brain Barrier with ease, in fact
    ( pay very close attention, National Geographic )
    Burbachers findings were it crosses the BBB easier! than does the FISH MERCURY. So, writer of this article, you are WRONG! and in doing so you, are absolutely guilty! of spreading misinformation. Not! us, the parents of the vaccine damaged. We seem to be the only ones seeking the truth in this matter. Everybody else, including all HHS agencies and AAP, is busy as a pack of dogs covering up dog crap. With one exception, the crap their busy covering
    up. Is the loss of a generation of American children through
    total incompetence creating science out of thin air.

    Dr Burbacher said, it also goes up into the brain and turns into INORGANIC mercury by 2 and a half times that as does the FISH MERCURY.

    Nation Geographic, it appears a retraction is in order.

  • NB

    Now I remember why I canceled my subscription to National Geo years ago. I don’t care to waste money on little more than the vacation albums of rich brats and I don’t care for pseudo-science junk like this. Correlation does not equal causation. Period.

  • NM

    Thank goodness someone is finally looking at this from a this angle. My son was born seemingly healthy, alert and quickly interactive. At 6 months we moved to Hong Kong, and within the year he began to develop signs of autism (although he has never been diagnosed). We have no autism in he family. He has had only 1 vaccine (Polio), has always eaten organic food and during pregnancy I was so paranoid about toxins that I didn’t even use deodorant or household chemicals of any sort.

    As he began to descend into an autistic state we had him tested and discovered that he was loaded to “tilting” with environmental toxins and heavy metals, including mercury. Additionally, his liver and kidney function were shot .

    Given the organic diet the primary thing that we can attribute this to is the environment. The pollution here is horrific – it’s in the water and it’s in the air (we’ve tested both). Coal fired plants spit out mercury and arsenic vapor. Constant renovation of neighboring apartments releases even more toxins into our immediate environment. Not only is my son affected, but one of my daughters and I have also been severely ill since moving here. Interestingly when we leave, if only for a week, the entire family feels much better.

    We have stared detoxing him and have seen tremendous improvement. Our plan is to move from here shortly and we can only home to see continued improvement.

  • Celia Bibby

    You all should read the following paper that was given free to the Autism World back in 1998.

  • kathy

    this is utter and complete crap! my son had seizures within an hour of receiving his vaccine for Dtap! he was diagnosed as autistic with in 3 weeks of that! he immediatly changed after he recievec his vaccines! Vaccines are very much to blame! Big pharma paid big money to publish such crap on here! next it will say-moms were over weight, underweight and smoking crack…dads are genetically inclined to produce autism, have bad genes, shot up, ate to many salads and drove to often…………. how many more lies can they feed the public? oh here is one, they stated on here that kids on medicade were more likely to be diagnosed, why?, well they didn’t say why!it just HAS TO BE TRUE, because they were on medicade. now back to reality- my son suffered very clearly from vaccines and i will state that FACT till someone listens!

  • Emily Willingham

    Well, NatGeo, you can now take pride in the fact that you’ve become a venue for the most strident anti-vaccine campaigners to come and peddle their misinformation, rather than being a trustworthy venue for fascinating, spectacular, evidence-based science.

  • joejoe

    Can someone please explain to me why heavy metals are safe in vaccines, and not safe in other forms? Its something that has interested me for the past 20 years, and all I get in response is lies, pseudo science, and lies again. So in the end there is no amount of safe heavy metals in vaccines or any other forms to be consumed or injected into a living organism, how hard is this to understand for anyone either studying or writing about this topic.

  • paul5of6

    It’s always telling when comments for a scientific article say that a certain topic should not be talked about because it’s pseudo-science or unscientific.

    Really, if you think these topics wont’ stand up to scrutiny, you should want these topics to be discussed and examined as much as possible.

    Science and censorship are incompatible.

  • Gina Waterman

    Draft one:

    Wow. Great article. I’m disappointed and disgusted with comments made by– I’m going to guess– people who have NO clue about the daily rigors of caring, raising and treating a child with Autism Spectrum Disorder — or whatever you want to call it.

    The truth of the matter is, no one knows — especially the doctors, neurologists, OBgyn’s, therapists — what causes Autism or how to eradicate it. What we should be focusing on is listening to parents and others who have solid feedback and evidence — yes I said it– to validate what happened to their child and come up with reasons why the child has neurological damage and share ways we can improve their condition, and therefore future.

    I am a parent of a 7 yr old boy with brain damage and a diagnosis of Autism. He was a 31 week preemie. He didn’t walk until age 2. He didn’t speak a word until age 4. Didn’t exchange glances or interact with others until age 5. I got him help along the way (nutrition, detox, supplements, homeopathy, alternative everything) and I trusted my instincts — despite the doctors. He wouldn’t be doing so well today had I only listened to medical doctors and so-called “experts”.

    Today he talks in full sentences, sometimes spontaneously. His reading level is past his grade. His gross motor skills are on par with peers. His fine motor skills are improving. He poops regularly and has been eating an organic GFCF diet since age 5.

    How long are we going to wait to do important research? How long are we going to wait to help these kids (who will soon be adults in our communities)?

    How long must we wait until someone looks up and says, oh yeah… maybe it’s something in the environment?!

    Isn’t it obvious yet? It is to us.

    The Parents.

  • SCR

    In 1999 my newborn son received the Hep B vaccine with 12.5mcg of mercury on the day of birth. At his 2,4 and 6 month shots he received more than the recommended EPA amount of mercury allowed for a 225# man. Now you are telling me this has nothing to do with his damaged immune system , his GI problems, his speech and social delays etc….Expose a developing brain to a toxic substance and what do you get…developmental delays. Do a google search for general anesthesia and learning disabilities/ADHD. It has been all over the news. Exposing a developing brain to toxins during a critical period of development (age 0-4) causes developmental delays and a host of medical problems in children. IMHO, injecting mercury is more harmful than eating seafood. Instead of pointing fingers let’s try to use some common sense.

  • […] Read the full article here: Zeroing in on the Causes of Autism – National Geographic […]

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