Autism's Link to Environmental Factors

As April 2, 2014 is the seventh annual World Autism Awareness Day, this is a fitting time to review some of the research on environmental factors that may contribute to the epidemic of autism. This complex developmental disability presents itself during the first three years of a person’s life. One in every 88 children in the US has been identified with an autism spectrum disorder (ASD). ASDs are almost five times more common among boys than girls. Autism is the result of a neurological disorder that has an effect on normal brain function, affecting development of the person’s communication and social interaction skills.

One study showed how pregnant women exposed to high levels of air pollution are twice as likely to have a child with autism.

According to a 2006 study from the Center on the Developing Child at Harvard University in Cambridge, MA, some toxic chemicals can interfere with the natural function of genes, proteins and other small molecules in the brain. This interference can lead to the onset of neurodevelopmental disorders, like autism. The paper states that the immature brain is much more vulnerable to toxic exposure than the brain of an adult.

There are more than 80,000 industrial chemicals in widespread use across the US. Around 3,000 of these chemicals are in products that we come into contact with every day, including clothing, carpets, toys, cleaning products and cosmetics. While the impacts of many of these chemicals is unknown, there are large numbers of chemicals that are known to be associated with neurodevelopmental disorders. These include lead, mercury, fluoride, dichlorodiphenyltrichloroethane (DDT), manganese, chlorpyrifos (a pesticide) and tetrachloroethylene (a solvent).

A study from the Harvard School of Public Health in Boston, MA, states that there are 214 unregulated chemicals that have been linked to human brain damage.

Another study from the university of Chicago found that rates of autism and intellectual disability in the US are correlated with genital malformation in newborn males, which is an indicator of fetal exposure to harmful environmental factors like pesticides. The research team found that for every 1% increase in malformations there was a 283% increase in autism and a 94% increase in intellectual disability. The researchers say this supports the presence of harmful environmental factors in these areas.

The researchers also discovered that male children with autism were almost six times more likely to have genital malformations at birth.

The research team also found that viral infections in males were linked to significant increases in incidence rates of autism and ID. Since exposure to environmental toxins is associated with the weakening of human immune systems, the researchers say this finding supports the theory that environmental exposure may be linked to autism and ID incidence.