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Do pesticides contribute to autism?
Here is the latest, excerpt:
Examining three years of birth records and pesticide data, scientists from the Public Health Department determined that the Central Valley women lived within 500 meters, or 547 yards, of fields sprayed with organochlorine pesticides during their first trimester of pregnancy. Eight of them, or 28%, had children with autism. Their rate of autism was six times greater than for mothers who did not live near the fields, the study said.
There is some attempt to look at larger numbers:
The scientists collected records of nearly 300,000 children born in the 19 counties of the Sacramento and San Joaquin river valleys. Of those children, 465 had autism. The scientists then compared the addresses during pregnancy to state records that detailed the location of fields sprayed with several hundred pesticides. For most pesticides, no unusual numbers of autism cases were found, but the exception was a class of compounds called organochlorines.
I am mostly skeptical. There are plenty of autistic children, here and abroad, who were never exposed to these chemicals. Agricultural valleys in California don't seem to have especially high rates of autism. Should I believe "you either get autism from your parents, or in some cases, from pesticides"? Or "pesticides are a potent epigenetic trigger"? Or should I believe "they found 465 cases out of 300,000 when they should have found many many more. Reporting of autism is biased in that sample, and the reporting bias is somehow correlated with certain kinds of agricultural activity."?
So far I'm sticking with the latter. Four points of note: a) the study author is appropriately cautious, b) he does try to adjust for regional diagnosis center, c) I very much wish this study had a map of incidence, and d) is it really so difficult for the author to discuss what it means that the study is restricted to just one part of California?
Posted by Tyler Cowen on July 31, 2007 at 11:35 AM in Science | Permalink
Comments
From an investigator's point of view, this is a starting point. From a judging point of view, it is hardly conclusive.
How about comparing autism records in non-farm areas? Indeed, how about in areas besides California?
One thought though, I can't help but wonder if the possible pesticide in question isn't used by gardeners, greenhouses or professional landscapers somehow. One would need to isolate non-farm usage before concluding that a non-difference in non-farm areas negates the hypothesis.
Posted by: happyjuggler0 at Jul 31, 2007 11:51:14 AM
An important fact is that autism isn't just one thing - it is a very loosely-defined collection of many disorders with many causes.
(The same applies to many other supposedly mysterious diseases like schizophrenia and Alzheimer's dementia - not one thing with one cause, but many things with many causes.)
Posted by: Bruce G Charlton at Jul 31, 2007 11:57:11 AM
This is the problem with trying to extract patterns where the event being investigated is rare. It's why drugs can go through extensive testing and still show up as having harmful effects when they go into general use. The percent of side effects was too small to be statistically significant in the original sample.
It also doesn't follow that there is only one cause for autism. Autism is a descriptive term. It defines the condition by outward signs, not by biochemical or physiological characteristics. So conditions which produce similar effects may be caused by different factors. If the study has identified one factor then it becomes a public health issue as what to do about this.
There are many substances which are known to cause birth defects and in some plants where these chemicals are handled there are restrictions on women of child bearing age being allowed to do certain tasks.
Even supposing the conclusions are stated more strongly than the data indicates the question still remains, what to do? Is it better to err on the side of caution or not?
Posted by: robertdfeinman at Jul 31, 2007 11:58:44 AM
For the true cause of autism see here: http://www.vitamindcouncil.com/health/autism/
Posted by: Dennis Mangan at Jul 31, 2007 12:12:39 PM
Mercury in vaccines is one of the leading causes of autism.
Posted by: kid mercury at Jul 31, 2007 12:41:39 PM
Kid:
Your posting illustrates another problem when people try to make policy decisions based upon science. This is that spurious, self-serving or deliberate misinformation lasts forever.
One crank site on the web, or one crank pundit who has a platform in print can just keep going on at length promoting their favorite theme. The fact that there is overwhelming evidence for the real scientific work counts for nothing.
Sometimes it is just pathetic as in those who still believe the world is flat, but too often bad science is used as a way for those with their own private agenda to promote their case.
Without going into the details of the issue with thimerosal again I will just state that it was the object of the largest public health study ever conducted, involving a whole country for over a decade. Those in the US who are still making claims otherwise have a financial interest in ignoring the science. They are trying to extract money from the vaccine fund to pay for their child's autism needs.
Are you deluded or do you or someone you know stand to benefit?
Posted by: robertdfeinman at Jul 31, 2007 12:54:05 PM
"For most pesticides, no unusual numbers of autism cases were found, but the exception was a class of compounds called organochlorines."
That sounds an awful lot like a data dredge. Test enough null hypotheses, and sooner or later you're bound to find one that looks statistically significant, purely by chance.
Posted by: Brandon Berg at Jul 31, 2007 1:05:01 PM
Brandon's right. If the different pesticides fall in different geographic arrangements, and there are enough pesticides, it's likely that one of them will be arranged similarly to the set of autistic kids.
Posted by: Jeff Brown at Jul 31, 2007 1:24:33 PM
Since we're actually in California, where my sons were conceived, born and live, I'd certainly be interested in seeing a map of incidence. Although we're in a large conurbation, and you could probably posit a theory of 'drift' and or subsequent water pollution, or crop pollution, the study would seem to offer up more questions than answers.
I'm interested in possible triggers, but I think it's hard to move far away from the gene pool.
Best wishes
Posted by: mcewen at Jul 31, 2007 11:25:31 PM
Autism was shamefully underresearched before this decade.
Posted by: Steve Sailer at Aug 1, 2007 3:57:18 AM
Tyler,
There are plenty of autistic children, here and abroad, who were never exposed to these chemicals.
I thought (as a layman) that it was pretty clearly established now that
autism a developmental brain abnormality from very early childhood
(probably mostly pre-birth).
Many things could potentially impact early development including possibly
insecticides.
Posted by: reason at Aug 1, 2007 5:03:09 AM
Simon Baron Cohen of Cambridge University is the go to guy here (no, it's not mercury in vaccines, nor the MMR one either).
Recent results in the UK indicate one in one hundred for autism spectrum disroders. So if these researchers found only 465 cases amongst 300,000 children it would appear that organochlorines are in fact prophylactics.*
* (No, not a serious comment).
Posted by: Tim Worstall at Aug 1, 2007 8:08:07 AM
Last thing I heard was an association between tech workers (nerds) and autism. A trait that makes you a good engineer, if amplified slightly through genes makes your children autistic.
Posted by: Ian Random at Aug 1, 2007 12:16:41 PM
http://autismdiva.blogspot.com/2007/07/autism-blame-bug-killers.html
I have a somewhat detailed discussion of the new study and point out some big ol' questions not answered by the reportage of it. Some of them you covered already.
Posted by: Autism Diva at Aug 1, 2007 10:45:54 PM
Mr. Feinman:
You state: "Without going into the details of the issue with thimerosal again I will just state that it was the object of the largest public health study ever conducted, involving a whole country for over a decade. Those in the US who are still making claims otherwise have a financial interest in ignoring the science. They are trying to extract money from the vaccine fund to pay for their child's autism needs. Are you deluded or do you or someone you know stand to benefit?"
A few points:
1. “Are you deluded…” It is not legitimate, responsible debate to resort to name-calling, innuendo, and personal attacks. Ad hominem attacks on one's opponents are a tried-and-true strategy for people who have a case that is weak.
2. What is this "largest public health study ever conducted? If you are talking about the Denmark studies, they have been pretty thoroughly discredited. See, e.g.:
http://www.safeminds.org/research/docs/Blaxill-DenmarkAutismThimerosalPediatrics.pdf
http://www.safeminds.org/research/docs/Hviid_et_alJAMA-SafeMindsAnalysis.pdf
Page 7 of http://www.safeminds.org/pressroom/pres_releases/060502Herman-unab.pdf
Surely you can do better. As for your accusations on “having a financial interest,” were you aware that all the authors on the Hviid study work for Statens Serum Institut, which is the manufacturer and promoter of vaccines in Denmark? JAMA, the journal that published the study, did not disclose that the authors had a financial conflict of interest in the study’s outcomes.
If you truly wish to rely on science, tell us what specifically are the best anti-mercury studies that you can come up with? I can come up with a plethora indicating that mercury at incredibly minute exposure levels causes severe neurocognitive developmental problems.
3. With respect to your own statements, I guess you are correct, “that spurious, self-serving or deliberate misinformation lasts forever.”
Posted by: ExanineTheData at Aug 2, 2007 8:22:04 PM
Examine:
Safeminds is not a scientifically recognized organization. It does not publish its results in peer-reviewed scientific journals and it assumes the answer it is seeking in its founding documents.
You need to read up more on how the scientific method works. You didn't rebut my question about the possibility of you having a personal interest in this topic.
I can state that I have no interest, I have never worked for any medical or biomedical firm and my only interest is in seeing the debasement of science by those without adequate understand stop.
Self-serving and misguided individuals have done much harm to all of us. When scientific data is disbelieved the results are two fold. Progress is slowed down and money is spent on wild goose chases.
You can not quote some ad hoc group of distressed parents and expect anyone to take their criticisms seriously.
Posted by: robertdfeinman at Aug 2, 2007 9:35:47 PM
Mr. Feinman:
You talk of peer-reviewed science, yet you avoided answering my questions:
What is this "largest public health study ever conducted" that you want readers to trust you on?
And I repeat: If you truly wish to rely on science, tell us what specifically are the best anti-mercury studies that you can come up with? I can come up with a plethora indicating that mercury at incredibly minute exposure levels causes severe neurocognitive developmental problems.
So put up your best peer-reviewed science - not parroted generalities - or please leave these discussion sites to grown ups.
And despite my warning that ad hominum attacks are the refuge of those with no substantive case, you attack Safeminds with ad hominum innuendo rather than confront the substance of their arguments. I guess we'll all have to assume that they are right and you aren't. Nuff said.
Oh, then you attack me with false innuendo: "You didn't rebut my question about the possibility of you having a personal interest in this topic." That was my first post above. So how could I be expected to rebut a question that you could not possibly have yet asked? (Boy, this guy is a real piece of work!)
My personal interest is that a few hours after my infant daughter was given multiple vaccinations, she devloped a 105F temperature which she had for two days. We had to put her in ice water to prevent brain damage. Then guess what? She regressed. She quit doing things she was doing before the vaccines and was stunted for two months. But she slowly clawed her way back. Perhaps her estrogen saved her. Was it the mercury in the vaccines? Who knows? No one would call her autistic today, but she was in only the 2nd-percentile in speech when she entered kindergarten and she still won't look anyone in the eyes. Problem is, I have heard similar stuff from many, many people. But don't worry - vaccines are completely safe!
And you admonish: "You need to read up more on how the scientific method works."! With all due respect, I work as a scientist much of each day and was a Kennedy Fellow of Science, Technology, and Public Policy at Harvard (ironically, where I studied quite a lot of economics...). Please, as requested before, let's argue the science. Otherwise, you are proving to other readers that you are relly just a wannabe.
Posted by: ExanineTheData at Aug 2, 2007 11:30:09 PM
I don't know what causes autism, but I can tell you it didn't appear in the 20th century. Waiting for a friend in a bookstore, I was looking at a dictionary of fairies and ran across the description of a changling, which stated that you know that the fairies had substituted a changling for your normal human child when your child suddenly stops making eye contact or speaking to its human family, starts making weird repetitive motions or sounds, and takes comfort in strange patterns or things. Further, any bizarre knowledge or abilities that such changlings might exhibit was proof of their fairy parentage -- after all, these were examples of things only a supernatural being could know. It was such a perfect description of autism and the abilities of the "idiot savant" that my blood ran cold. Then (the book being a fairy dictionary, of course) it went onto describe the ways to persuade the fairies to give your child back -- most of which involved killing the changling, in order to convince the fairies that you were serious about harming their creature -- and added that the defense to infanticide by claiming the child was a "changling" was used in England until the 19th century.
I think the only thing new about the sudden onset of autism in otherwise normally developing children is that we are now less sure of the explanation.
Posted by: Diana at Aug 3, 2007 12:55:12 AM
I don't know what causes autism, but I can tell you it didn't appear in the 20th century. Waiting for a friend in a bookstore, I was looking at a dictionary of fairies and ran across the description of a changling, which stated that you know that the fairies had substituted a changling for your normal human child when your child suddenly stops making eye contact or speaking to its human family, starts making weird repetitive motions or sounds, and takes comfort in strange patterns or things. Further, any bizarre knowledge or abilities that such changlings might exhibit was proof of their fairy parentage -- after all, these were examples of things only a supernatural being could know. It was such a perfect description of autism and the abilities of the "idiot savant" that my blood ran cold. Then (the book being a fairy dictionary, of course) it went onto describe the ways to persuade the fairies to give your child back -- most of which involved killing the changling, in order to convince the fairies that you were serious about harming their creature -- and added that the defense to infanticide by claiming the child was a "changling" was used in England until the 19th century.
I think the only thing new about the sudden onset of autism in otherwise normally developing children is that we are now less sure of the explanation.
Posted by: Diana at Aug 3, 2007 12:57:17 AM
Diana -
This is actually a favored hallucination of "autism culture" (see: http://en.wikipedia.org/wiki/Autistic_culture).
Among the diseases with symptoms that match the description of changelings in various historical legends are spina bifida, cystic fibrosis, PKU, progeria, homocystinuria, Williams syndrome, Hurler syndrome, Hunter syndrome, and cerebral palsy, as well as some autism. For elaboration, see, especially: http://en.wikipedia.org/wiki/Changeling
So it certainly doesn't "prove" that autism has been around for centuries.
Note that few of these fables describe flapping, spinning, stimming, totally uncommunicative, diapered older children.
Posted by: ExanineTheData at Aug 3, 2007 10:11:01 AM
Examine:
I'm sorry that you have had a personal experience with autism and that this has blurred your vision in this area.
I'm not going to argue the scientific validity of the existing studies with you since you already know all the answers. But you belong to the class of people that has a direct interest in proving a link between vaccinations and autism and this makes your statements biased. This is not an ad hominem attack just a statement about human nature.
I'll leave you with a series of quotes:
"This is like nothing I've ever seen before," Dr. Melinda Wharton, deputy director of the National Immunization Program, told a gathering of immunization officials in Washington in March. "It's an era where it appears that science isn't enough."
and:
"It's really terrifying, the scientific illiteracy that supports these suspicions," said Dr. Marie McCormick, chairwoman of an Institute of Medicine panel that examined the controversy in February 2004.
and finally:
"It doesn't seem to matter what the studies and the data show," said Ms. Ehresmann, the Minnesota immunization official. "And that's really scary for us because if science doesn't count, how do we make decisions? How do we communicate with parents?"
Posted by: robertdfeinman at Aug 3, 2007 10:51:25 AM
Mr. Fineman:
In my own daughter's case, I find it hard to believe that she would have such a strong, immediate immunological reaction to ethylmercury. Clearly it was something in at least one of the vaccines, and I know little of immuniology, but I have no evidence that it was mercury. However, there is clearly something wrong with the status quo of current vaccine practice.
With respect to widespread neurological impairments, I do believe that mercury exposure is very much to blame, and there certainly appears to be excellent scientific evidence that it may be responsible for some autism, and certainly much ADHD. This comes from a wide reading of recent biomedical research. For those interested in actually examining the science, please see my multiple posts at:
http://episteme.arstechnica.com/eve/forums/a/tpc/f/158007275731/m/981000056831/p/1 (in the bottom half)
with addresses to download many of the original papers.
Then let's ExamineTheData and debate the studies instead of relying on regurgitated generalities.
I would be happy to argue the science here. That is exactly what is needed.
Posted by: ExanineTheData at Aug 3, 2007 12:03:55 PM
Examine:
It is well known that a small percentage of people experience adverse reactions to various vaccines. This is why there is a formal mechanism to deal with this from a liability point of view.
What has happened over the centuries is that the perception of risk to reward has shifted. When smallpox vaccination first started there was a substantial risk of real adverse reaction, but the alternative was considered so much worse that people took the risk. When the worst happened they accepted this as part of the risk.
Now many of the diseases that people get vaccinated for are so rare that most people aren't even aware of them. So when something goes amiss they feel that they need to be compensated. Perhaps this is a sign that the risks haven't been adequately explained, but then many would refuse the vaccinations and this has public health implications as well.
People increasing want life to be risk free and find it necessary to blame someone (preferably with deep pockets) when things go wrong. I don't know what the right balance is. I think that people should probably be compensated for misfortunes that were avoidable, but other than that I don't know.
If you cut off you fingers with a table saw is that the maker's fault? (All saws have built in safety features, after all.)
As for discussing the "science". I'm not a biologist and there are many other forums for this sort of thing. I assume you are already participating in the appropriate places. As I said my interest is in seeing that science isn't debased anymore that it already has been. Libertarians are especially good at confusing "liberty" with social necessity. Some of them use false science to bolster their case. Autism is just another of these instances where emotion, politics and financial interests get mixed in with science.
I will admit that the drug companies haven't been helping the cause in recent years as the number of false claims and cover ups that they are responsible for continues to grow. That is why we are supposed to have independent review bodies like the FDA. Having the industry fund the oversight regulatory agency has led to a compromise of their role as well.
Posted by: robertdfeinman at Aug 3, 2007 3:54:45 PM
The study linking pesticides with autism certainly needs to be explored further. Although the persons in the study lived near fields where pesticides were used, children consume these pesticides when they eat the food or drink the juice. Even though more developed countries have tried to control their use, we are still exposed. And now with imports coming from around the world where banned pesticides are used to the extreme, we should consider their impact more carefully.
Posted by: charleymc at Sep 29, 2007 9:54:50 AM
The study linking pesticides with autism certainly needs to be explored further. Although the persons in the study lived near fields where pesticides were used, children consume these pesticides when they eat the food or drink the juice. Even though more developed countries have tried to control their use, we are still exposed. And now with imports coming from around the world where banned pesticides are used to the extreme, we should consider their impact more carefully.
Posted by: charleymc at Sep 29, 2007 9:55:14 AM
