Environmental causes
Environmental Factors
While the genetic contributions to the development of Autism Spectrum Disorders are significant, there are also likely to be significant environmental contributions to the development of autism. There are many chemicals which significantly increase the risk for neurodevelopmental disabilities, including lead and organophosphate insecticides. Additionally epidemiology studies indicate a higher rate of incidence of autism in areas of the country with higher levels of pollution. However, it is difficult to ascertain if the increase in autism cases is due to pollution.3
Additionally, frequent exposure to high-production-volume (HPV) chemicals, many of which have not been tested for neurodevelopmental toxicity. A recent study that aimed to identify chemicals which were potentially toxic to the developing brain found approximately 200 chemicals that were neurotoxic to adult humans. Most of these were industrial chemicals (metals, solvents, and pesticides). They also created a list of 1000 chemicals which were found to be neurotoxic in experiments, but have not been directly examined in humans.
Causation of ASD has been found in environmental exposure to Thalidomide, Misoprostol, Valproic acid2, prenatal rubella infections, and Chlorpyrifos.1
Citations
1. Landrigan PJ. What causes autism? Exploring the environmental contribution.Curr Opin Pediatr. 2010 Apr;22(2):219-25. PMID 20087185
2. Moore SJ et. al. A clinical study of 57 children with fetal anticonvulsant syndromes.J Med Genet. 2000 Jul;37(7):489-97. PMID 10882750
3. Rada RE. Controversial issues in treating the dental patient with autism. J Am Dent Assoc. 2010 Aug;141(8):947-53. PMID 20675420
