Evidence based medicine shows that autism spectrum disorder is caused by the interplay of multiple genetic factors and environmental risk factors (Karimi, et al. 2017). Environmental factors and chemical exposure may affect the pathophysiology of the nervous system, hormone system or immune system causing the developmental disorder known as autism.
According to Gaugler and colleague (2014), the estimated heritability of autism spectrum disorder is approximately in the range of 50-60%. But there are hundreds of the “novo” gene mutations linked to autism risk, which contribute substantially to individual liability. It is estimated that 41% of individuals with autism have environmental factors and chemicals that target the same molecular pathways affected by the novo autism-linked mutations (e.g. CHD8, NRXN1, UBE3A, SCN2A, ADNP, etc.). Kalkbrener and colleague (2014) report that the combination of genetic and environmental factors may disrupt and interfere with neuron formation and migration, synapse formation, neurological connectivity and ultimately cause autism spectrum disorder.
There is a relationship between the paternal and maternal age with autism. In addition, some drugs such as Valproate, an anticonvulsant used for people with epilepsy, mood stabilizers for bipolar disorder, anti-depressants such as Selective Serotonin Reuptake Inhibitors (SSRIs)), and drugs for migraines, may increase prenatal risk to developing autism spectrum disorder (ASD).
Toxic chemicals such as lead, methylmercury, arsenic, mercury, cadmium, aluminum, manganese, alcohol, maternal smoking, and pesticides) have been identified as harmful during the first trimester of pregnancy. Organochlorine compounds (OCCs) such as Polychlorinated biphenyl ethers (PCBs) may influence risk of autism spectrum disorder (Modabbernia et al/, 2017; Mandy and Lai (2016). Moreover, a study called “CHARGE study “(Childhood Autism Risks from Genetics and Environment), Shelton et al. (2014), found positive associations between autism and prenatal exposure to organophosphate pesticides. Lyall et al. (2017) report that prenatal exposure to pyrethroids, a chemical found on food, in houses and in humans, stimulates early gene expression and increases the risk for autism. Likewise, exposure to fungicides such as strobilurin, to azoxystrosbin found in wallboards used throughout homes, and to Pyraclostrobin found in conventional foods and in baby foods, may pose similar risks.
More studies and technologies are needed that use environmental sampling data to assess exposure threat to humans and to find other chemical risks for autism spectrum disorder. In addition, we need to create alerts to families who may be exposed to organophosphate, pyrethroid, or carbamate pesticides during gestation in order to decrease the risk for autism and other neurodevelopmental disorders.
Francisco Monegro currently serves as the residential Clinical Director of adult services programs at QSAC. He is also a consultant on autism for the PSCH clinic and the Shield Institute. Dr. Monegro received his MD/PhD in clinical psychology from the University of Santo Domingo/University of Kansas. In 1988, he received a diploma from the American Board of Medical Psychotherapists, Nashville, and from the International Academy of Behavioral Medicine, Counseling and Psychotherapy, Dallas, TX.