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Scientists warn of chemical-autism link
June 7th, 2011
06:43 PM ET

Scientists warn of chemical-autism link

Autism and environmental health experts called for greater scrutiny of chemicals found in the environment, which could potentially lead to autism and other neurodevelopmental disorders, in a conference call Tuesday.

"We live, breathe and start our families in the presence of toxic chemical mixtures and constant low-level toxic exposures, in stark contrast to the way chemicals are tested for safety," said Donna Ferullo, Director of Program Research at The Autism Society.

"Lead, mercury, and other neurotoxic chemicals have a profound effect on the developing brain at levels that were once thought to be safe," she said.

Autism spectrum disorders are being diagnosed at unprecedented rates, partly because of improved diagnostic tools and criteria, but also a host of other factors including what mothers-to-be are exposed and consequently their unborn children too, said Irva Hertz-Piccotto, Chief of the Division of Environmental Health at the University of California, Davis, and a faculty member at the Mind Institute.

About 1 in 110 children in the United States has autism, a group of developmental disorders that lead to impairments in behavior, communication and socialization. The cost of autism is staggering: $3.2 million for the care of a person with autism throughout his or her life; behavioral therapy can be hard to come by and be very limited,  and most medications don't help much.

Studies have strongly suggested a genetic component in the cause of autism, but it's becoming clear that genetics alone isn't the whole story; there could be interactions between susceptibility genes and environmental chemicals.

Recent research from her group, appearing in the journal Epidemiology, showed that prenatal vitamins taken prior to conception seem to interact with certain metabolizing genes that are inherited.  Those women who did not take the vitamins, and had the high-risk genotypes, were more likely to have a child with autism.  Still, this was a small study limited in scope, and more research should be done to confirm these findings.

The central nervous system of the fetus is sensitive to a wide range of chemicals, Hertz-Piccotto said.  Hormones, such as estrogens and androgens, are essential for proper brain development. Endocrine-disrupting compounds need more research, she said. Flame-retardant chemicals called PBDEs interfere with the body's hormones.  Even though many of them are no longer used in manufacturing, they can hang around in the environment and the human body for a long time.  The Environmental Protection Agency (EPA) is aware of concerns about these chemicals and is working on accessing substitutions (see the action plan).

Bisphenol A, present in plastic food packaging and water bottles, among other products, is another big concern, she said, because it could interfere with the body's natural estrogen system; antimicrobials added to soaps, toothpaste and other products can artificially enhance androgenic activity.

"That means that they could potentially play a role in autism or other neurodevelopmental disorders," Hertz-Piccotto said.

Moreover, many children with autism spectrum disorders have abnormal immune responses. The chemical messengers in the immune system interact with the receptors in the brain, so chemicals that affect immunity could also be implicated in autism.

Thyroid dysfunction is common in children with autism that psychiatrist Dr. Suruchi Chandra sees, even though that's not part of the classical symptoms of the condition.  She believes the abnormalities are due to the thyroid hormone disruptors such as BPA and flame retardants.

"Thyroid hormone is critical for brain development in early life, and even small alterations in hormone levels can have serious consequences; long-lasting and perhaps irreversible consequences in terms of brain function," she said.

Air pollution from traffic and certain pesticides have also been shown to have associations with autism, studies have shown.  Maternal conditions could partially result from chemicals in the environment.

Andy Igrejas, National Campaign Director of Safer Chemicals, Healthy Families, called for an update of the 1976 Toxic Substances Control Act. Sen. Frank Lautenberg (D-NJ) has proposed a stricter version that would require all industrial chemicals to be tested for safety.

UPDATE: Since so many of you have asked, I wanted to clarify that this discussion does not relate to vaccines. The scientific evidence available has shown again and again that vaccines do not cause autism.


soundoff (1,193 Responses)
  1. autismwars

    Dr. Gupta, tell me how chemicals in the air, water and food CAN cause autism, but chemicals injected into newborns through vaccines cannot?

    September 18, 2012 at 07:20 | Report abuse | Reply
  2. Sarah

    Great article... until the update. You do not have to be a medical doctor or a PhD to come to the conclusion that the same toxins, which are present in vaccines, are a contributing factor in autism. And vaccines have the added problem of not being the natural way that an immune system works, especially the immature immune systems of very young children. Thanks for the info on toxic chemicals and I hope that you get the big picture soon.

    September 18, 2012 at 12:38 | Report abuse | Reply
  3. Jill

    Even kids who have disabilities, and mental retardation don't act, and do the same things as kids with autism. This is not new as it turns out autistic people were locked in mental hospitals, and asylums. When autism showed up people started getting vaccinated. Why would I believe anything the news or the government has to say when these same people are covering it up. Look how it would affect the drug companies if people don't get vaccinated. I have to live a life of constant stress, and struggle with my son who is severe autistic, and we have no insurance coverage. There is no way this is natural, and try telling people this when they breast feed. The government is slow killing their own citizens the politicians don't have the guts to even mention autism during the conventions. Considering that more kids are getting diagnosed. It will affect us all my other two kids who don't have it will not be going to college enjoy running government with no workers, and no money.

    September 18, 2012 at 18:27 | Report abuse | Reply
  4. Jill

    There is a toxic chemical link, and here is why it is vaccines real simple. Even though people are exposed to everyday chemicals, and lets not forget that toxic chemicals are being sprayed into our skies daily by government. Chemtrails are not natural clouds by the way. That is only minimal exposure complared to getting chemicals injected directly into your bloodstream. A merck scientist even admits in a video that vaccines can cause aids, and cancer.

    September 18, 2012 at 18:55 | Report abuse | Reply
  5. Dulce Penfold

    Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by rare mutations, or by rare combinations of common genetic variants.:..:"

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    June 8, 2013 at 05:11 | Report abuse | Reply
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Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.