Chlorpyrifos, an organophosphate chemical, used heavily as an agricultural insecticide, is also directly linked to being a cause of Autism (ASD).
Please notice, from the map on the above article, how heavily Chlorpyrifos was used in the 1990s in the Midwest, and that, even now there is resistance to eliminate its use, despite the pesticide being a known cause of major brain development defects in children.
Even if parents (from the start of this insecticide’s use by Dow in 1966 to present day) make healthy food choices for themselves before & during pregnancy, trace amounts of this pesticide are on foods—unless it was labeled “organic”—and in water sources. Fetuses exposed in utero to the pesticide are affected, and young children develop conditions.
No wonder that within 2 generations, Americans have seen an exponential increase in Autism (10% over 40 years & 15% from 2012 to 2018), as well as increased ADD and ADHD, in their children. Our genetics cannot withstand the onslaught of pesticides designed to kill worms’ neurological system. https://www.autismspeaks.org/science-news/cdc-increases-estimate-autisms-prevalence-15-percent-1-59-children
Here is the medical article naming the pesticide as a cause of Autism.
https://ehp.niehs.nih.gov/doi/full/10.1289/ehp.1104285
Another widely used, household chemical variety directly linked to cause ASD are Phthalates.
Phthalates are a group of chemicals used to make plastics more flexible and harder to break. They are often called plasticizers. Some phthalates are used as solvents (dissolving agents) for other materials. They are used in hundreds of products, such as vinyl flooring, adhesives, detergents, lubricating oils, automotive plastics, plastic clothes (raincoats), and personal-care products (soaps, shampoos, hair sprays, and nail polishes).
Phthalates are used widely in polyvinyl chloride plastics, which are used to make products such as plastic packaging film and sheets, garden hoses, inflatable toys, blood-storage containers, medical tubing, and some children’s toys.
https://www.cdc.gov/biomonitoring/Phthalates_FactSheet.html
In addition to Phthalates, the chemical Thalidomide, used in prescription acne treatment solutions like Accutane and Thalomid, is a known cause of birth defects including Autism.
“Studies suggest an association between exposure to manganese in drinking water and neurological issues in infants and children, such as changes in behavior, lower IQ, speech and memory difficulties, and lack of coordination and movement control.” https://www.wqa.org/learn-about-water/water-q-a/manganese