Heavy pollution linked to risk of autism,
study shows
A new study links diesel emissions to autism syndrome. (The Oregonian, Beth
Nakamura)
By Soumya Karlamangla, The Oregonian
on June 17, 2013 at 9:01 PM, updated June 17, 2013 at 9:55 PM
Pregnant women exposed to heavy diesel pollution are twice
as likely to have a child with autism as those living in areas
with low pollution, according to a study published today.
Researchers from the Harvard School of Public Health
found that diesel, mercury, lead, manganese and methylene
chloride in the air significantly increased the risk of having a
child with autism.
The results add to a growing body of research that links air
pollution to autism, said Andrea Roberts, the Harvard
study's lead author. The data shows a strong correlation
between pollution and autism, though it stops short of
proving causation. Still, the research suggests something in
the air could be harming fetuses.
This is the first large national study to examine links between
autism and air pollution. Researchers examined data from
long-term study 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 U.S. Environmental Protection Agency data to
estimate exposure and also adjusted for factors such as
income, education and smoking during pregnancy.
The study comes in the midst of efforts to slash Oregon's
pollution levels -- Portland has the state's highest levels of
toxic pollution -- in addition to a growing focus on autism
and its causes as rates increase around the country.
Anton Swenson, a Beaverton resident, said his son's
Asperger disorder -- a milder form of autism -- took its toll
emotionally and financially on his family. His son, now 20,
needed extra health care and medicine. At home he pushed
his parents away because he didn't want to be touched and
showed signs of depression. A twin sister doesn't have
autism.
"It's bad enough for just the average kid going through
certain stages, but you add something in like autism
spectrum and you're in a whole other level, a whole other ball
park," Swenson said. He and his wife lived in Northeast
Portland about half a mile from Interstate 84 during her
pregnancy.
The diagnosis of autism in recent years almost doubled
nationwide: one in 150 children had been diagnosed with
autism in 2000, it was one in 88 children by 2008.
The Harvard study identified diesel as the most dangerous
pollutant when it comes to autism. Diesel particulate matter
is not a single chemical, but a toxic mix of fine particles that
generally come from diesel truck exhaust fumes or
construction equipment that settles in the lungs. Exposure to
high levels of diesel has been strongly linked to cancer and
respiratory illnesses like asthma.
The state Department of Environment Quality found in a
2012 report that Portland's level of diesel particulate
matter, along with seven other toxics, was more than 10
times higher than the air quality health benchmark set by the
state.
But even that benchmark isn't strict enough, says
Multnomah County Chairman Jeff Cogen. Both California
and Washington set standards for reducing diesel
pollution roughly 30 times more stringent than
Oregon's, and Cogen thinks the state should follow our
neighbors' lead. Diesel pollution is much stronger within
1,500 feet of major roads and highways, and minorities in
the Portland metro area tend to be disproportionately
affected by this kind of pollution.
"Low-income people and people of color are exposed to
much higher levels of diesel pollution," he said. "So it's not
just a health issue, it's a social justice issue."
And that social justice issue could have just gained a new set
of implications.
Oregon already has the second-highest rate of autism among
students in the country, with its average double the national.
However, that number is based on the type of education a
student is receiving in school and unlike most states, Oregon
does not require a medical diagnosis to join a special
education class.
The number of students identified as autistic rose in the
2011-'12 school year by 300 students, approximately 3
percent, according to data released by the Oregon
Department of Education earlier this year.
Roberts, the Harvard author, recommended that expectant
mothers worried about autism take prenatal vitamins and
eat food high in healthy oils, both of which have been shown
to reduce risks of autism. She also said to stay away from
cigarette smoke and to try to maintain a healthy weight to
prevent gestational diabetes, also linked to autism.
"Even though air pollution might be tough to avoid, there are
other things that might be helpful and will help the baby
anyhow, independent of autism," she said. The research
being published online in the journal, Environmental Health
Perspectives.
--Soumya Karlamangla