Autism/mercury poisoning?

[Guest guest]

Questions and answers

 

For years, parents have been concerned that a mercury-containing

vaccine preservative may play a role in autism. But a study conducted

in California found that autism rates increased even after thimerosal

was removed from most vaccines. The study authors say this is evidence

that thimerosal does not cause autism, although advocacy groups say

it's too soon to determine whether autism rates have been affected. Do

these findings suggest that autism isn't linked to mercury in vaccines?

 

Dr. Sanjay Gupta, chief medical correspondent: Let me explain. In

1999, manufacturers began removing thimerosal - which is a

mercury-based preservative - from vaccines. Some people believed

autism would decrease as a result, because they thought the two were

connected. A new study in the Archives of General Psychiatry says this

just didn't happen. Researchers looked at cases of autism in

California after 1999. They reasoned that if mercury exposure in

vaccines was a major cause of autism, the number of affected kids

should have dropped after thimerosal was removed.

 

Just the opposite happened. From 2004 to 2007, when exposure to

thimerosal dropped significantly for 3- to 5-year-olds, the autism

rate continued to go up, from 3 per 1,000 children to 4 per 1,000

children in California. Video Dr. Gupta: Watch more on the

autism-vaccine link controversy »

 

A child psychiatrist who supported the study said it " very clearly

shows that autism did not arrive through a vaccine. " But advocacy

groups say it's too soon to determine whether autism rates were

affected by removing thimerosal from vaccines. The National Vaccine

Information Center says the study doesn't include children under the

age of 3, which they say is the only group that was never exposed to

mercury in vaccines. It says thimerosal wasn't completely off the

shelves until 2002 or 2003. Their main point is that mercury is a

neurotoxin, so why take a chance by putting it in vaccines?

 

What do scientists think causes autism?

 

As many as one in every 166 children in this country is found to have

autism, and doctors still don't know why. Doctors point to genetics

and environment as culprits, but it could be more complicated than

that. The latest research shows these children are not necessarily

born with autism but with the potential to develop it. What exactly

are these outside factors? It's hard to pinpoint. What we eat, what we

breathe, what we drink -- all these things could play a role. Some

doctors say the increase is due to a change in the way the condition

is diagnosed kids who were once labeled mentally retarded are now

being labeled as autistic.

 

What are possible signs of autism in your child?

 

Doctors are now looking for signs of autism in children as young as 18

to 24 months.

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Some red flags that indicate your child may have autism: no babbling

or pointing by 12 months, no single words by 16 months, no brief

phrases by 24 months, loss of language or social skills. If you see

any of these signs, the American Academy of Pediatrics recommends

seeing a pediatric neurologist, developmental pediatrician or child

psychologist.

 

What led companies to remove thimerosal from vaccines to begin with?

 

Several things pushed companies in this direction. Over the past

decade, more and more attention was given to the health effects of

mercury on humans. And then in the '90s, the CDC added new vaccines to

the list of routine shots that children should get. Some of them used

thimerosal as a preservative. This was happening while the government

was trying to decrease our exposure to mercury. So the FDA began

looking into the issue. In 1997, Congress passed a bill that mandated

review of products containing mercury, which led manufacturers to

begin removing thimerosal from vaccines two years later.

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Background

CNN spoke with Dr. Eric Fombonne, a professor of psychiatry at McGill

University in Montreal, Quebec, and an autism expert, who wrote a

commentary accompanying the Archives of General Psychiatry study. Here

are a few of his comments:

 

Fombonne: Several different studies, with different designs, performed

in different countries have all failed to show a link between

thimerosal and autism. This is particularly important in the U.S.

context because so many more people believe thimerosal is implicated

in autism [in the U.S.], than in other countries. Years ago, people

made predictions -- by removing thimerosal, the number of cases of

autism should decrease -- therefore showing that thimerosal is a cause

of autism. This new study puts that idea in jeopardy. Similar studies

have been done in Canada and Denmark with the same results: thimerosal

was removed, but autism is still on the rise. This is a strong

message; it very clearly shows, and reassures, that autism did not

arrive through a vaccine. ...

 

All theories have been tested, there's lots of empirical data. We have

an accumulation of studies -- science posits in accumulation. Now,

focus can be placed on possible environmental or genetic factors,

because thimerosal has been ruled out. Also, parents should not fear

vaccines.

 

CNN also spoke with Dr. Pauline Filipek, at the University of

California, Irvine, School of Medicine and the founder of OC Kids, a

center for autism. Here are excerpts from the conversation.

 

CNN: What are your thoughts on this new study?

 

Filipek: I think it's fabulous. I think it's long overdue. I've been

using the graphs that [show these rates] in my lectures. I have been

showing when thimerosal was totally removed. Now there is a formal

study to show there is no association ... with a lot more scientific

validity. If there was a connection with the mercury, I should be

almost out of business as an autism specialist by now, eight years

later, because there should not be any more children with autism if it

was caused by the mercury in the vaccine.

 

Some parents say this study presents a greatly oversimplified

explanation of a very complex problem. ... The party line has been

that mercury causes all of autism. This adds to the data that disprove

that.

 

CNN: Is it safe to say this study proves there is no link between

autism and vaccines?

 

Filipek: I don't think any one study would definitely prove that. But

I think it gives formal credence to what the institute of medicine has

said and what other studies have said. I think the data is now that

much stronger.

 

CNN: How do you explain rising numbers?

 

Filipek: I can't explain it at this point in time. I think that it is

a complex question with complex answers. Some of it is due to the

broader diagnostic criteria, some of it is due to the greater

recognition, but most certainly not all of it can be explained by

those two.

 

CNN: The group also said that some vaccines containing thimerosal had

expiration dates as late as 2005 and may have been used up to that point.

 

Filipek: ... We know there's a strong genetic component to autism, but

that can't explain the increase. So there must be something else at

work. ... We do know that environment can influence genetics. We are

understanding more and more how the environment interplays or

interacts with genetics. But that field is still very, very young,

relatively speaking. If it was so simple as being mercury in the

vaccines, it should be going away. Even if there were mercury in some

vaccines, even if that statement's true, the rates should have

plateaued. ... I think it's one more study that disproves the link.