Claim: Air pollution causes autism

This is junk science because…

… if this were true, autism rates would have exploded in the U.S. in the 1940s and continued high until the 1970s or so. Moreover, autism rates would be soaring in China right now. Additionally, the researchers have no idea how much air pollution any study subject was exposed to in this harvesting-of-statistical-noise type study.

The media release is below.

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Exposure to high pollution levels during pregnancy may increase risk of having child with autism

Boston, MA — Women in the U.S. exposed to high levels of air pollution while pregnant were up to twice as likely to have a child with autism as women who lived in areas with low pollution, according to a new study from Harvard School of Public Health (HSPH). It is the first large national study to examine links between autism and air pollution across the U.S.

“Our findings raise concerns since, depending on the pollutant, 20% to 60% of the women in our study lived in areas where risk of autism was elevated,” said lead author Andrea Roberts, research associate in the HSPH Department of Social and Behavioral Sciences.

The study appeared online June 18, 2013 in Environmental Health Perspectives.

Exposure to diesel particulates, lead, manganese, mercury, methylene chloride and other pollutants are known to affect brain function and to affect the developing baby. Two previous studies found associations between exposure to air pollution during pregnancy and autism in children, but those studies looked at data in just three locations in the U.S.

The researchers examined data from Nurses’ Health Study II, a long-term study based at Brigham and Women’s Hospital involving 116,430 nurses that began in 1989. Among that group, the authors studied 325 women who had a child with autism and 22,000 women who had a child without the disorder. They looked at associations between autism and levels of pollutants at the time and place of birth. They used air pollution data from the U.S. Environmental Protection Agency to estimate women’s exposure to pollutants while pregnant. They also adjusted for the influence of factors such as income, education, and smoking during pregnancy.

The results showed that women who lived in the 20% of locations with the highest levels of diesel particulates or mercury in the air were twice as likely to have a child with autism as those who lived in the 20% of areas with the lowest levels.

Other types of air pollution—lead, manganese, methylene chloride, and combined metal exposure—were associated with higher autism risk as well. Women who lived in the 20% of locations with the highest levels of these pollutants were about 50% more likely to have a child with autism than those who lived in the 20% of areas with the lowest concentrations.

Most pollutants were associated with autism more strongly in boys than girls. However, since there were few girls with autism in the study, the authors said this finding should be examined further.

Senior author Marc Weisskopf, associate professor of environmental and occupational epidemiology at HSPH, 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.”

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Other HSPH authors included Alberto Ascherio, professor of epidemiology and nutrition; Kristen Lyall, visiting scientist in the Department of Nutrition; Jaime Hart, instructor in the Department of Environmental Health; Francine Laden, Mark and Catherine Winkler Associate Professor of Epidemiology in the Department of Epidemiology; Allan Just, research fellow in the Department of Environmental Health; and Jennifer Bobb, research fellow in the Department of Biostatistics.

Support for the study came from DOD W81XWH-08-1-0499, USAMRMC A-14917, NIH T32MH073124-08, P60AR047782 and R01ES017017-04. The Nurses’ Health Study II is funded in part by NIH CA50385.

“Perinatal air pollutant exposures and autism spectrum disorder in the children of Nurses’ Health Study II participants,” Andrea L. Roberts, Kristen Lyall, Jaime E. Hart, Francine Laden, Allan C. Just, Jennifer F. Bobb, Karestan C. Koenen, Alberto Ascherio, and Marc G. Weisskopf, Environmental Health Perspectives, online June 18, 2013

Harvard School of Public Health brings together dedicated experts from many disciplines to educate new generations of global health leaders and produce powerful ideas that improve the lives and health of people everywhere. As a community of leading scientists, educators, and students, we work together to take innovative ideas from the laboratory and the classroom to people’s lives—not only making scientific breakthroughs, but also working to change individual behaviors, public policies, and health care practices. Each year, more than 400 faculty members at HSPH teach 1,000-plus full-time students from around the world and train thousands more through online and executive education courses. Founded in 1913 as the Harvard-MIT School of Health Officers, the School is recognized as America’s first professional training program in public health.

20 thoughts on “Claim: Air pollution causes autism”

  1. I guess about now we’ve had anything from aluminum in vaccines to mercury in fish supposedly ‘causing’ autism. These claims are possible because autism such as defined in the manuals doesn’t exist. It is the same problem as with diabetes type 2. Everything lumped together that vaguely resembles

  2. Just another vague cause, when will we get real answers? Blame it on pollution, blame it on the mother, the father, and my favorite the grandfather.
    Blame it on age, blame it on mother being abused, blame it on faulty genes,
    blame it on epilepsy drugs during pregnancy. I wish they would quit beating around the bush and get down to business so this epidemic ( some people don’t call it that?) could come to an end. Thanks!!

  3. As suggested in the lead-in, pollution was high 30+ years ago in the US and increasing in China. Pollution is decreasing in the US, so why wouldn’t autism rates track those trends if the study were valid? Could there be bias toward diagnosing “autism” in heavily populated (and likely more polluted) areas compared to less populated areas? Also, what concentrations of what material lead to autism?

  4. Point, but I think you’re going too far in the other direction. Cancer is in a similar vein. In the end, cancer is a symptom, an effect, without actually specifying the causes (which are myriad) of the resulting tumors which range from viral to mutagenic to genetic to seemingly random chance. However, I don’t anyone would state that cancer doesn’t exist. It’s a class instead of a disease per-se.

  5. If you broaden the definition of autism and expand the search, you will find more cases of autism, including an increased number of false positives. This is similar to avian influenza. If you examine every dead bird you come across you will find more cases of bird flu.

  6. Why next you will be telling us that air pollution, like cigarette smoking, is good for us…..

  7. And the purpose of continuing grants is to find a substance that can be regulated, controlled, and taxed in the name of fighting autism.

  8. This is old news; there was a paper by a Harvard (where else of course) professor a few years ago who postulated this. Every liberal cause is tied in with every other one. If we just keep funding climate change, renewable energy, women’s health, AIDS research and treatment, unions, big government, the UN, subSahara Africa, etc. all will be well with the world.

  9. Of course. Money fixes everything–as long as it’s money you took from someone who actually earned it. Charity, on the other hand, fixes nothing. Only forcibly removed money cures the ills of the world. 🙂

  10. Autism did start to increase in the US in the 40s. Oh, and car pollution is a huge component, hence the ongoing problem in the US. And it 1% in China, compared to the .1-.2% globally. Autism diagnosis in China began in the 80s and have climbed since then. Your analysis is correct – your inputs are wrong. The things you say WOULD be true IF pollution were related to autism are, in fact, true.

  11. According to the statistics I find, rates for autism were 2-4 per 10,000 until 1980 in the USA, when they rose significantly. According to the CDC, the rates between 2000 and 2008 went up nearly 40%. The EPA reports over a 50% drop in air pollution (CO2, lead, SO2, PM. NO and VOC) since 1980. Since pollution levels were decreasing and autism sky rocking, it seems unlikely pollution is the cause. Some of the “increase” is due to vastly expanded definitions of autism. Beyond that, the theories are numerous and the proof of said theories sadly lacking. We just do not know.

  12. Have there been any studies done in China on the connection between pollution and Autism. If not, it’s probably not a good science to use China as an example.

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