Exposure to air pollution during pregnancy increases the risk of an autistic birth

A group at Harvard led by an Israeli researcher examined a group of 245 mothers of autistic children, and a control group of more than 1,500 mothers of healthy children. and made a correlation between them and the air pollution data during pregnancy

Dr. Leo Kanner, a member of an ultra-Orthodox family from Galicia who immigrated to the USA, was probably the first child psychiatrist in the world. He studied the field himself, which was new at the time, and in 1930 he established the first department of child psychiatry at the Johns Hopkins University Hospital in Baltimore. He managed it for almost 30 years until his retirement, and continued to be active in it until his death in 1981. He left behind many students who continued his work, textbooks he authored and many studies, but most of all his name is remembered thanks to one term he coined: autism. In an article he published in 1943, Kenner described 11 children with very similar disorders, including difficulty in acquiring language and non-verbal communication, difficulty in expressing emotions and a series of other behaviors that prevent them from forming personal and social relationships. These children seemed to him to be contained within themselves, so Kenner called the phenomenon autism (from the Greek word "auto" - self). In fact, he used a term coined before him by several European doctors, including the Austrian Hans Asperger (the one after whom the famous syndrome is named), but they used the term in a different context, and Kanner was the first to give it the accepted usage today.

factors in alta

In the decades that have passed since Kenner's first diagnosis, diagnostic tools and medical research have been greatly improved, and many more syndromes have been added accompanied by various communication disorders, or other behavioral disorders that are largely reminiscent of classical autism, the one described by Kenner. All these disorders are now described as part of the autistic spectrum (autistic spectrum), which covers a huge variety of phenomena, from relatively mild learning and communication disabilities, to profound autism that causes total dysfunction.
Although the phenomenon has been known for almost seven decades, the causes of autistic disorders are still far from clear. Many studies done on the matter yielded partial results at best. Genetic predisposition is probably one of the causes, at least for some of the disorders, but it explains perhaps a small part of the autism cases (it is very difficult to determine precisely, because so far not a single gene directly related to autism has been identified). Another phenomenon that probably increases the risk is problems during the development of the brain and the nervous system, such as certain diseases in infancy. In the past, unfounded rumors were spread that vaccines for toddlers cause autism, but all serious studies that have examined the issue have found no such connection. Quite a few studies find a circumstantial relationship between various environmental factors and the risk of autism, including the age of the father (late fatherhood increases the risk level), certain diseases of the mother during pregnancy, as well as smoking during pregnancy. Some studies also pointed to air pollution as a possible cause, but most of them were not sufficiently substantiated.

Sisters in distress

The one who decided to investigate in depth the issue of the connection between air pollution and autism is Dr. Raanan Raz, an epidemiologist who went to do post-doctoral training at the School of Public Health at Harvard University. Raz and his colleagues used data from the American Nurses' Health Survey for their research. Thousands of nurses (medical) from all over the USA who volunteered to participate in the health survey, answer every two years or so on a questionnaire sent to them by researchers. For the purpose of the current study, the researchers added to the questionnaire some questions for the study participants, if they have children with disorders on the autism spectrum. Based on the answers, they put together a group of 245 mothers of autistic children, and a control group of more than 1,500 mothers of healthy children. In the next step, they turned to air pollution data collected by the American Environmental Agency, EPA. They calculated with the help of a mathematical model the estimated level of pollution in the place of residence of each of the women during pregnancy and found a clear connection between the level of exposure and the degree of risk of autism in the child born to them. Moreover, the higher the level of exposure to pollution, the higher the level of risk. At the highest levels of pollution, the risk of being born autistic was ten times higher than at the lowest levels of exposure. Another finding revealed that there is no clear connection between the levels of exposure to air pollution before or after pregnancy, and the risk of giving birth to an autistic child. The relationship was found only during pregnancy, and an especially increased risk was discovered in the last trimester of pregnancy. The researchers also tried to examine whether there is a relationship between the level of exposure to air pollution and the severity of autism, but the data they had from the nurses' questionnaire was not enough to get a clear answer.

We continue in the country

Although the statistical findings are very clear, the researchers are cautious about jumping to conclusions because it is still unclear biologically how the infection may cause autism. The assumption is that the pollution particles are absorbed into the lungs, and are absorbed through them into the bloodstream. They make their way to the fetal brain, where they cause inflammation that increases the risk of developing an autistic disorder. The findings of the study may be able to help the brain and development researchers to focus their research in this direction, although it is very difficult to study the causes of phenomena such as autism, in the absence of a good model in laboratory animals. Raz, who recently returned to Israel, now works at the Ministry of Health and is leading an even more comprehensive study on the connection between air pollution and autism. In this study, the researchers hope to recruit a larger number of participants and obtain more accurate diagnoses of the children, in an attempt to also quantify the effect of the infection on the severity of the disorders. Also, in the American study, only one group of pollutants was actually tested - particles with a diameter of up to 2.5 microns (that is, 2.5 thousandths of a millimeter). In the Israeli study, the researchers intend to examine a wider variety of particles, including dust particles, to examine whether the many sandstorms and foggy days in our region have an effect on the level of autism risk.

no prevention

The study by Raz and his colleagues, published in the journal Environmental Health Perspectives, joins a growing line of studies pointing to the health risks of air pollution. According to the World Health Organization, seven million (!) people die each year prematurely due to exposure to pollution. Studies show that exposure to pollution increases, among other things, the risk of heart disease, stroke, respiratory diseases and lung cancer. The enormous medical damage causes a heavy financial burden both on the families of the patients, and on the health system of the country - every country. At least the financial damage could have been prevented if they had invested from the beginning even a small proportion of the expected cost of air pollution damage - in reducing the emission of polluting substances.

Related links:

The research article in the journal Environmental Health Perspectives
World Health Organization data on air pollution and morbidity