Autism is the general term for autism spectrum disorder (ASD), the DSM-5 classification for four similar neurodevelopmental disorders that affects one in 68 American children (1). The four subtypes include autistic disorder, childhood disintegrative disorder, pervasive developmental disorder-not otherwise specified (PDD-NOS), and Asperger syndrome (1). Signs of autism usually appear between two and three years old and manifest as difficulties in social interaction, communication, repetitive behaviors, intellectual disability and emotional dysregulation (1)(2). The Centers for Disease Control provides a concise description of ASD; "…developmental disabilities that cause substantial impairments in social interaction and communication …show more content…
Environmental triggers come from the external world and are introduced into the individual. Possible environmental factors include, but are not limited to, toxins, chemical, and pollutants. It is theorized that these environmental factors may cause damage during prenatal or perinatal development. One study conducted in Denmark titled, Urbanicity and Autism Spectrum Disorders, found that proximity to urban environments was an identified risk factor for development of ASD. This study included 800,000 children living in Denmark, 4,000 of these children were found to have ASD. In their study of geographic variation of ASD they found a dose-response link between increased occurrence of ASD and proximity to urban environments. This association included both children who lived in urban environments at birth as well as children who migrated to these areas after birth (Lauritsen, Astrup, Pedersen, Obel, Schendel, & Schieve, 2014). Although the authors note that this study did not explore specific reasons why these associations existed it does provide an example where the environment has played some role in the occurrence of ASD. Taking the next step, this second study explored the prevalence of ASDs in relation to their proximity to industrial facilities. These researchers found industrial facilities that released arsenic, lead, or mercury into the environment and compared these locations to data from the Autism Developmental Disabilities Monitoring (ADDM) network which track records of cases of Autism. The study found that proximity to these facilities did impact rates of ASDs. ASD prevalence was higher in the closest 10th percentile as compared to those in the furthest 50th percentile (Dickerson, Rahbar, Han, Bakian, Bilder, & Harrington, 2014). This study suggests that there are environmental factors at play when it comes to