Environmental pollutants are all around us. How are they affecting human brains? My hypothesis is that there is a correlation between these widespread chemicals and neuropsychological disorders. I have read and written about four disorders; autism spectrum disorder, attention deficit hyperactivity disorder, schizophrenia and bipolar disorder which I have tried to correlate to environmental pollutants; metals, endocrine disrupting chemicals, pesticides and air pollutants through literature (through searching Google Scholar and PubMed). Most research found supports my hypothesis of a correlation between pollutants and neuropsychological disorders both in epidemiological studies as well as studies conducted on humans. Additionally there are animal studies that show correlation between different chemicals found in nature and traits or symptoms characteristic for a certain disorder. The findings show correlation but also raise other questions such as; what role do additional aspects play, such as social and demographic influences? What is the reason of the skewed gender bias towards the male sex in autism spectrum disorder and attention deficit hyperactivity disorder?