Air Pollution,  Featured,  Health,  Science,  Toxic Exposure

Autism and Air Pollution Go Together

By The Editors

Autism, a severe developmental disorder that begins within the first three years after conception, is considered a global concern. The causes of autism are not well understood. Now, results from a study published online today, June 18, in the scientific journal “Environmental Health Perspectives” show that women exposed to air pollutants during pregnancy are up to twice as likely to have an autistic child than those living in areas with low air pollution.

What is autism? The American Psychiatric Association defines autism as a disorder characterized by deficits in social interactions and communication skills, as well as the presence of stereotypic and repetitive behaviors. According to the Autism Research Institute “Most autistic children look like other kids, but do puzzling and disturbing things which are markedly different behaviors from those of typical children. In less severe cases on the spectrum (Pervasive Developmental Disorder (PDD) or Asperger’s Syndrome), children usually have speech and might even be intellectually gifted, but they have one or more “autistic” social and behavioral problems.

The study has been carried out by researchers at the Harvard School of Public Health. The researchers examined data from Nurses’ Health Study II, a long-term study that began in 1989 (you can read more about the Nurses’ Health Study II here). Based at Brigham and Women’s Hospital, it involves 116,430 nurses from 14 U.S. states. The researchers studied 325 women who had a child with autism and 22,000 women who had a child without the disorder and examined the associations between autism and levels of pollutants at the time and place of birth. To estimate women’s exposure to pollutants while pregnant, the researchers used air pollution data from the U.S. Environmental Protection Agency (EPA), while adjusting for the influence of factors such as income, education, and smoking during pregnancy.

The results show that exposures to diesel, lead, manganese, mercury and methylene chloride while pregnant were significantly associated with development of autism spectrum disorder. The correlation between mercury and diesel was particularly high.

For most pollutants, associations were stronger for boys (279 cases) than girls (46 cases) and significantly different according to sex.

Senior author Marc Weisskopf, associate professor of environmental and occupational epidemiology at the Harvard School of Public Health, said, “Our results suggest that new studies should begin the process of measuring metals and other pollutants in the blood of pregnant women or newborn children to provide stronger evidence that specific pollutants increase risk of autism. A better understanding of this can help to develop interventions to reduce pregnant women’s exposure to these pollutants.”

However, it would be wise to consider alternative explanations for the apparent association of autism and air pollution found in this study. For example, all women involved in the study were nurses – may be taking a look at occupational exposure is not a bad idea. At the same time, we can expect nurses to have easier access to medical care and therefore to accurate diagnosis. May be diagnosis of autism, because of easier access to health care, is more frequent in a group consisting of nurses as compared to the general population – if this is the case, then interpretation of results should be adjusted to take into consideration such a factor.

According to the World Health Organization (WHO) “Despite the high burden of autism and other developmental disorders in children and adolescents, these conditions have been widely neglected by policy makers and public health experts, particularly in low- and middle-income countries. As a consequence, children and families in need have often poor access to services and do not receive adequate treatment and care. Greater investments in advocacy, awareness, research, and services and human resource development are needed.”

Hopefully, this study will raise awareness and will be just a step in the research ladder that will lead to the prevention and treatment of autism.


  • Shirley Belshazzar

    Being born in India, autism and pollution got my attention. Growing up, we were exposed to pollutants constantly. We woke up breathing the soot from cooking, using wood and dung as fuel. We bathed in the same pond where cattle got theirs. We walked to school breathing exhaust from vehicles. Reading one of the article posted on “times of India” newspaper, April 2, 2013, 1 in every 88 children in India under age 3 are autistic. The condition has gotten worse between 1947 and 2013. This is the same period when pollution went up. ( For the last 70 years there have been studies to determine the causes of autism but no specific answers. There are studies that show positive correlation between pollution and acute respiratory infections in children in India. Maybe it is time to further investigate the relationship between pollution and autism.

  • jgunn5

    I personally find this interesting because this is a huge issue that is studied in Los Angeles due to the fact it is one of the most polluted cities in the United States. I have a nephew who resides in Los Angeles that was diagnosed with autism when he was roughly around the age of 3. When this happened I began to do research about the different ways studies say autism occurs and one particular study I followed was being done by the Department of Epidemiology at the University of California, Los Angeles. They particularly studied the affects of traffic-related air pollution during pregnancy.

  • Nisha Hudda

    Autism has become known as the “hidden epidemic” of the United States. This post explains a very crucial factor about autism and that is that a pregnant women exposed to pollution are more likely to have an autistic child. I am aware that pollution causes many health risks, but autism being on that list is quite shocking. The pregnant women should be required to take a test to measure metal and pollutant levels. I think that women who are pregnant should stay away from heavy metal environments such as factories or even traffic in the city. There have been studies that are relevant to autism stating that women who are pregnant who choose to smoke have a very high risk of having a baby with autism because of the nicotine which effects the child’s brain. Autism is a disorder, which is becoming very common here in the United States. I believe that we need to focus on our environment, which includes the air pollution to have a better and healthy environment for all. This will hopefully decrease the health risks, which are a problem for our society today.

    • sb2013

      In 2008, scientists have identified two proteins in the brain that links nicotine usage and autism. The neurexin-1 beta protein activates another protein which is a type of nicotinic acetylcholine receptor whose role is to help neurons communicate signals. This function is important in autism because research has also shown that autism patients lack these nicotinic receptors. People who are addicted to nicotine on the other hand too many of these receptors. Neurexin-1 protein is made by neurexin-1 gene. Thus it is assumed that there is a genetic link between synapse formation and nicotinic receptors. They are also looking at cholinergic agents as potential treatment. These medications should be re-processed so that they could increase the level of neurexin-1 beta proteins. ( I was also thinking if second hand smoking can contribute to autism at all.

  • cdao22

    Maternal exposure to toxic chemicals is an underestimated factor for the development of many disorders in children. I bet similar results will show up for other types of pollution and disorders in the next few years.

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