Article 9-11landrautism.doc

What causes autism? Exploring the environmental contribution
Current Opinion in Pediatrics
January 16, 2010
Philip J Landrigan, MDFrom the Department of Community and Preventive Medicine, Department of Pediatrics, Children's Environmental Health Center, Mount Sinai School of Medicine,New York, USA.
PURPOSE OF REVIEW:Autism is a biologically based disorder of brain development.
Genetic factors - mutations, deletions, and copy number variants - are clearly implicated in causation of autism. However, they account for only a small fraction ofcases, and do not easily explain key clinical and epidemiological features. Thissuggests that early environmental exposures also contribute. This review exploresthis hypothesis.
RECENT FINDINGS:Indirect evidence for an environmental contribution to autism comes from studiesdemonstrating the sensitivity of the developing brain to external exposures such aslead, ethyl alcohol and methyl mercury.
But the most powerful proof-of-concept evidence derives from studies specificallylinking autism to exposures in early pregnancy - thalidomide, misoprostol, andvalproic acid; maternal rubella infection; and the organophosphate insecticide, There is no credible evidence that vaccines cause autism.
Children today are surrounded by thousands of synthetic chemicals. Two hundred ofthem are neurotoxic in adult humans, and 1000 more in laboratory models. Yetfewer than 20% of high-volume chemicals have been tested forneurodevelopmental toxicity.
This article explores the contribution of early environmental exposures to toxic chemicals to the causation of autism.
The prevalence of autism is substantially higher than a decade ago. Similar increases are noted in England, Europe, and Japan.
“Genetic factors are thought to account for 7-8% of autism cases.” A purely genetic explanation for causation of autism is unlikely.
Environmental chemical toxin exposures can play a role in autism causation.
“These factors could act in concert with inherited susceptibilities or through inducingepigenetic changes.” There is “exquisite vulnerability of the developing human brain to toxic Exposure of lead and methylmercury toxic chemicals can damage the developing human brain and produce neurodevelopmental disorders and subclinicaldysfunction.
“The developing human brain is understood today to be exquisitely susceptible to injury caused by toxic chemicals in the environment. Thevulnerability is greatest during embryonic and fetal life, and may be especially greatin the first trimester of pregnancy.” The “tip of the iceberg” chemicals that cause neurodevelopmental disabilities There are more than 80,000 chemicals with potential human exposure More than 1,000 chemicals are known to be neurotoxic in experiments 201 chemicals are known to be neurotoxic in humans 8 chemicals are proven to be neurotoxic to human neuroevelopment “Children today are at risk of exposure to 3,000 synthetic chemicals produced in quantities of more than 1 million pounds per year.” “Given current understanding of the great vulnerability of the developing brain to toxic chemicals, likelihood is high than many of the [documentedchemicals] have potential to cause injury to the developing brain and to produceneurodevelopmental disorders,” including autism.
There is both clinical and epidemiological evidence that autism is linked to Documented in utero exposures that can cause autism include: MisopostolThis drug is designed to protect gastric ulcers; it is also used as an abortifacient [a substance that induces abortion] Valproic acidA drug used as an anticonvulsant, for mood stabilization, epilepsy, bipolar disorder, depression, migraine, and schizophrenia[Depakote, Depakene, Depacon, Stavzor] Chlorpyrifos“Chlorpyrifos is an organophosphate insecticide widely used until a few years ago to control insects in schools and homes in the US and still used extensively inagriculture.” They also cause significant developmental delays, cognitive deficits and attention deficit hyperactivity disorder (ADHD).
This author believes that autism is primarily caused by exposure to high- production-volume (HPV) chemicals to “which women and children today are High-production-volume (HPV) chemicals are those produced in quantities greater than 1 million pounds per year, and are commonly found in consumer goods, cosmetics, medications, motor fuels, building materials, etc. “They areroutinely detected in air, food, and drinking water. Measurable quantities of severalhundred HPV chemicals are found in the blood and urine of nearly all Americans, aswell as in human breast milk and the cord blood of newborn infants.” This author suggests that the chemicals most likely to be causative of autism and therefore those that should have the highest priority for study include:A)) Organohalogens [when a carbon is bonded to a halogen (fluorine, chlorine, bromine, iodine); used in refrigerators, air conditioners, pesticides, herbicides, andas solvents]C)) The genetic contribution to autism is very small.
Most cases of autism are linked to environmental exposures to toxic Autism was first documented in 1943.
There is historic evidence that autism is linked to exposure to lead, ethyl There is proof that autism is linked to prenatal exposure to thalidomide, misoprostol, and valproic acid; maternal rubella infection; and the organophosphateinsecticide, chlorpyrifos.
There is no credible evidence that vaccines cause autism.
“Children today are surrounded by thousands of synthetic chemicals. Two hundred of them are neurotoxic in adult humans, and 1,000 more in laboratorymodels. Yet fewer than 20% of high-volume chemicals have been tested forneurodevelopmental toxicity.” A purely genetic explanation for causation of autism is unlikely. “Genetic factors are thought to account for 7-8% of autism cases.” Early environmental toxin exposures may contribute to the causation of “The developing human brain is understood today to be exquisitely susceptible to injury caused by toxic chemicals in the environment.” The “tip of the iceberg” chemicals that cause neurodevelopmental disabilities “Children today are at risk of exposure to 3,000 synthetic chemicals produced in quantities of more than 1 million pounds per year.” “Given current understanding of the great vulnerability of the developing brain to toxic chemicals, likelihood is high than many of the [documentedchemicals] have potential to cause injury to the developing brain and to produce neurodevelopmental disorders,” including autism.
There is both clinical and epidemiological evidence that autism is linked to Documented in utero exposures that can cause autism include: This drug is designed to protect gastric ulcers; it is also used as an abortifacient [A substance that induces abortion] Valproic acidA drug used as an anticonvulsant, for mood stabilization, epilepsy, bipolar disorder, depression, migraine, and schizophrenia[Depakote, Depakene, Depacon, Stavzor] “Chlorpyrifos is an organophosphate insecticide widely used until a few years ago to control insects in schools and homes in the US and still used extensively inagriculture.” They also cause significant developmental delays, cognitive deficitsand attention deficit hyperactivity disorder (ADHD).
This author believes that autism is primarily caused by exposure to high- production-volume (HPV) chemicals to “which women and children today areroutinely exposed.” High-production-volume (HPV) chemicals are those produced in quantities greater than 1 million pounds per year, and are commonly found in consumergoods, cosmetics, medications, motor fuels, building materials, etc. “They areroutinely detected in air, food, and drinking water. Measurable quantities of several hundred HPV chemicals are found in the blood and urine of nearly all Americans, aswell as in human breast milk and the cord blood of newborn infants.” This authors suggest that the chemicals most likely to be causative of autism and therefore those that should have the highest priority for study include: Organohalogens [when a carbon is bonded to a halogen (fluorine, chlorine, bromine, iodine); used in refrigerators, air conditioners, pesticides, herbicides, andas solvents] The genetic contribution to autism is very small.
Most cases of autism are linked to environmental exposures to toxic

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