In The Politics of Autism, I discuss various ideas about what causes the condition. Here is just a partial list of correlates, risk factors, and possible causes that have been the subject of serious studies:
- Air pollution and proximity to freeways;
- Maternal thyroid issues;
- Autoimmune disorders;
- Induced labor;
- Preterm birth;
- Birth by cesarean section;
- Anesthesia during cesarean sections;
- Maternal and paternal obesity;
- Maternal diabetes;
- Maternal and paternal age;
- Maternal post-traumatic stress disorder;
- Smoking during pregnancy;
- Antidepressant use during pregnancy;
- Polycystic ovary syndrome.
- Infant opioid withdrawal
- Zinc deficiency
- Processed foods
At Occupational and Environmental Medicine, Erin C McCanlies and colleagues have an article titled "The CHARGE Study: an Assessment of Parental Occupational Exposures and Autism Spectrum Disorder."
What is already known about this subject?
The speed with which the incidence of autism has increased suggests the importance of risk factors other than genetics in the aetiology of autism spectrum disorder (ASD) and, currently, several dozen epidemiologic studies have observed associations with prenatal exposures to environmental chemicals and pollutants. Since occupational exposures often exceed environmental levels, investigation of their role as risk factors for ASD is warranted in the search for potentially modifiable aetiologic agents.
What are the new findings?
Maternal occupational exposure to solvents occurred more often in the parents of children with ASD compared with TD [typically developing] children.
How might this impact on policy or clinical practice in the foreseeable future?
Future research should consider maternal occupational exposures to solvents as a potential risk factors in the aetiology of ASD and focus on identifying specific solvents rather than broad categories of solvents. Larger studies or different types of study designs may help to identify other risk factors in the aetiology of ASD and further clarify the role solvents may have in the risk of ASD.From the article:
This study indicates that maternal occupational exposure to solvents may be associated with higher rates of ASD in their children. These results should be interpreted with caution given that this association did not remain significant after correcting the P-values for multiple comparisons. However, these results are consistent with earlier reports that have identified solvents as a potential risk factor for ASD.5 9 28 Research in the non-ASD population has found that solvents can be absorbed into the blood via skin or lungs.29 Water-soluble solvents may be cleared out of the body in urine or faeces, but many solvents are retained in organs including the brain. Solvents can also be metabolised into more toxic secondary substances (eg, methyl-butyl ketone, n-hexane) that are associated with a number of neurological effects and changes.29 In infants, solvents have been found to interfere with the glial guidance process which inhibits neuritic outgrowth.30 Infants of mothers who have been exposed to occupational solvents or those who abuse solvents (eg, sniff toluene) show delayed speech and motor function as well as cognitive deficits.12 Although these later studies did not specifically evaluate the effects of solvents and ASD, they do suggest mechanisms by which maternal occupational solvent exposure may interfere with typical brain development and hence be involved in the aetiology of ASD.