Air pollutants linked to autism

A study finds that air pollutants, such as those from cars and trucks, may increase risk for autism development.

A researcher at the University of Wisconsin-Milwaukee (UWM) has added to a growing body of evidence that links autism to air pollutants such as those generated by cars and trucks.

Amy Kalkbrenner's study, published this week online at the journal Epidemiology, showed that pollution's impact on autism rates in North Carolina is similar to results of pollution-autism studies in California -- despite weather and climate differences between the two states.

In addition, the work of Kalkbrenner and her colleagues, building on previous studies, showed that women in the third trimester of pregnancy were more susceptible to the damaging effects of air pollution on their unborn child.

"It adds another piece supporting the hypothesis that environmental chemicals are part of the autism puzzle," says Kalkbrenner, an assistant professor in UWM's Joseph J. Zilber School of Public Health. Autism, a spectrum of disorders affecting interpersonal relations and work achievement, now affects some 1 in 68 children in the U.S.

Her research team focused on exposure to coarse and fine particulate matter, known as PM10, which arises in part from traffic-related air pollution. The study evaluated records in the two states, covering pre-conception through the first birthday for 87,000 children in North Carolina and 77,500 in California born in the mid-to-late 1990s. Key regions in each state were selected based on researchers' ability to simultaneously measure the level of particulate matter present, and know which children had autism in these regions.

Researchers used a new, more exact tool to measure the levels of particulate matter in smaller slices of time, based on pollution at the family's address during pregnancy. With this method, they were able to compare exposures during specific weeks of pregnancy. The approximately one thousand children who later developed some form of autism spectrum disorders were then compared to all other children.

Kalkbrenner says it was important to look at eastern states because of the differences in climate, seasonal weather patterns and the chemical make-up of the particulate matter that might impact brain development. "Evidence for a link between a chemical exposure and a health impact like autism is stronger when it can be shown in more than one region." The team found that the concentration of particulate matter was highest among children born in summer months in North Carolina and those born in fall and winter months in California.

Reasons for increased susceptibility in the third trimester of pregnancy are not known at this time. However, Kalkbrenner says this finding is consistent with theories that show links between autism and altered brain network development, specifically synaptic connections that are developing during the final months of pregnancy.

"We've now had three solid studies saying the same thing. The evidence is pretty compelling that something is going on with air pollution and autism," says Kalkbrenner, who adds that further study is needed to determine the neurodevelopmental impacts of specific chemical pollutants during precise developmental windows.

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Autism and the environment

A study discusses how environmental factors may increase a person's risk of developing autism.

A large U.S. study suggests environmental pollution might be contributing to autism risk, although the specific culprit toxins remain unknown.

Researchers analyzed medical records and found a correlation between U.S. counties' autism rates and their rates of genital birth defects in boys, which could be a sign of some common environmental contributors.

However, the findings, which were reported March 13 in the journal PLoS Computational Biology, do not prove that any particular environmental exposure directly raises the risk for the developmental disorder, experts said.

There's no "smoking gun," said Alycia Halladay, senior director of environmental and clinical sciences for the advocacy group Autism Speaks.

"This study was not designed to figure out what the [environmental] factors are," said Halladay, who was not involved in the research.

Still, she said, experts believe autism arises from a combination of genetic vulnerability and any number of environmental exposures. Some suspects include infections such as flu during pregnancy, certain prescription drugs taken during pregnancy and environmental toxins.

These latest findings support the "scientific agreement that it's a mix of genes and environment," Halladay said.

The lead researcher on the study agreed. "Both genes and environment are important," said Andrey Rzhetsky, a professor of genetic medicine at the University of Chicago.

The task ahead, Rzhetsky said, is to figure out which environmental exposures matter.

Autism refers to a collection of disorders, usually diagnosed during childhood, that affect language and social skills.

For the study, Rzhetsky's team analyzed nearly 100 million U.S. health insurance claims for a county-by-county look at rates of autism and intellectual disability. They also examined rates of genital malformations in boys -- such as micropenis, undescended testicles and hypospadias (in which the urethral opening is on the underside of the penis).

Those genital malformations were used as an indicator of parents' exposure to environmental pollutants, Rzhetsky said. The exact causes of those birth defects are not clear, but some studies have suggested that certain environmental toxins -- including pesticides and lead -- might play a role, he said.

In this study, county rates of genital birth defects ranged from none to just over 2 percent. Overall, the researchers found, for every 1 percent increase in those birth defects, the rate of autism rose by close to 300 percent.

Even accounting for county demographics, a strong link existed between rates of genital defects and autism, Rzhetsky said.

But the reasons for the correlation aren't clear. Genes could play some role, Rzhetsky said, and so could environmental factors other than pollutants.

Halladay said endocrine disruptors -- chemicals found in plastics, food cans and other everyday products -- have been linked to genital birth defects. But so far, researchers haven't found a connection to autism risk.

On the other hand, some studies have found a link between high exposure to air pollution during pregnancy and an increased autism risk, Halladay said.

Researchers continue to look for the environmental players in autism, Halladay said. Autism Speaks has a program that funds research on the environmental factors -- including toxic exposures and nutrition during pregnancy -- that might affect autism risk.

Rzhetsky said he hopes his team's findings help fuel the interest in that type of research. "There is a lot of research focused on the genetics," he said. "But environment plays a big role."

But chemicals in the environment are only one potential reason autism rates vary across the United States.

Rzhetsky's team also found lower rates of autism in states where regulations require a doctor's diagnosis of autism before kids can qualify for special education.

Halladay said the finding is consistent with past studies suggesting that differences in diagnosis help explain regional differences in autism rates.

A 2012 study from the U.S. Centers for Disease Control and Prevention found that one in 88 U.S. children had an autism spectrum disorder -- up almost 25 percent from just a few years before. But the rate varied widely, from one in 47 in Utah to one in 210 in Alabama.

Experts speculated that the national increase had a lot to do with better detection, and that differences in awareness and autism services might explain the regional differences.

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Pollution exposure during pregnancy increases risk of autism in children

A study shows that women who are exposed to high levels of air pollution during pregnancy are more likely to have a child with autism.

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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Study: Autism Risk for Developing Children Exposed to Air Pollution

This study discusses a possible link between exposure to air pollution during pregnancy or while an infant and the development of autism in the child. Is this another epigenetic factor? JR

Research conducted by University of Southern California (USC) and Children's Hospital Los Angeles scientists demonstrates that polluted air -- whether regional pollution or coming from local traffic sources -- is associated with autism.

The study titled "Traffic Related Air Pollution, Particulate Matter, and Autism," shows that exposure to traffic-related air pollution during pregnancy and the first year of life is associated with a more than two-fold risk of autism. In addition, exposure to regional pollution consisting of nitrogen dioxide (NO₂) and small particles -- particulate matter less than 2.5 and 10 microns in diameter (PM2.5 and PM10) -- is also associated with autism even if the mother did not live near a busy road. The study is published in theArchives of General Psychiatry, a sister publication of the Journal of the American Medical Association.

"This work has broad potential public health implications," said the study's principal investigator, Heather Volk, Ph.D., assistant professor of preventive medicine at the Keck School of Medicine of USC and investigator in the Division of Research on Children, Youth and Families at Keck School-affiliated Children's Hospital Los Angeles. "We've known for a long time that air pollution is bad for our lungs, and especially for children. We're now beginning to understand how air pollution may affect the brain."

The research is the first to look at the amount of near-roadway traffic pollution individuals were exposed to and combine that with measures of regional air quality. The study builds on previous research by Volk and colleagues that examined how close subjects lived to a freeway, said Volk, who also has appointments at the Keck School's Zilkha Neurogenetic Institute and Department of Pediatrics.

"We took into account how far away people lived from roads, meteorology such as which way the wind was blowing, how busy the road was, and other factors to study traffic-related pollution," she said. "We also examined data from air quality monitors, which measure pollution over a larger region that could come from traffic, industry, rail yards, or many other sources."

In the 2012 study, Volk and colleagues from USC and the University of California, Davis examined data on 279 autism cases and 245 control subjects enrolled in the California-based Childhood Autism Risks from Genetics and the Environment (CHARGE) study. Mothers' addresses from birth certificates and addresses reported from a residential history were used to estimate exposure during each trimester of pregnancy and the first year of life. The researchers used air pollution levels derived from the Environmental Protection Agency's Air Quality System to determine exposure to NO2, PM2.5, and PM10. They also applied dispersion models to estimate the amount of traffic the mothers and children were exposed to.

Particularly interesting was the effect of mothers' and children's exposure to particles, both PM10 and PM2.5. PM10 includes both coarse and fine particles, while PM2.5 includes only the smaller (fine) particles, which are most likely to have deleterious effects on the human body.

"From studies conducted in the lab, we know that we can breathe in tiny particles and they can produce inflammation," said Volk. "Particles have varied composition, and there are many chemicals that can bind to them. The components of these particles could be hazardous to the brain."

Other researchers who participated in the study include Irva Hertz-Picciotto, University of California, Davis; Rob McConnell from USC; and Fred Lurmann and Bryan Penfold from Sonoma Technology, Inc.

The research was funded by the National Institute of Environmental Health Sciences (grant 1 R21 ES019002-01).

Volk and colleagues are now at work on a study of how genes related to autism may be affected by environmental exposures to try to identify if there are factors that make people are genetically more vulnerable to particular pollutants.

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Prenatal Pollution Exposure May Worsen Asthma in Children

The link between prenatal exposure to air pollution and childhood lung growth and respiratory ailments has been established by several studies in recent years, and now a new study suggests that these prenatal exposures can be especially serious for children with asthma.

The study will be presented at the ATS 2012 International Conference in San Francisco. "In this study, we found that prenatal exposures to airborne particles and the pollutant nitrogen dioxide adversely affect pulmonary function growth among asthmatic children between 6 and 15 years of age," said study lead author Amy Padula, PhD, post-doctoral fellow at the University of California, Berkeley. "This analysis adds to the evidence that maternal exposure to ambient air pollutants can have persistent effects on lung function development in children with asthma."

The study was conducted as part of the Fresno Asthmatic Children's Environment Study (FACES) -- Lifetime Exposure initiative, which examines the influence of prenatal exposure to a number of ambient air pollutants on the growth of lung function during childhood and teen years in a high pollution area.

For this analysis, the researchers included repeated evaluations of 162 asthmatic children between the ages of 6 and 15 and their mothers. To determine prenatal exposure levels to pollution, the mothers' residences during pregnancy were geocoded and pollutant concentrations were obtained from the Aerometric Information Retrieval System supported by the U.S. Environmental Protection Agency (EPA).Monthly average pollutant concentrations were assigned from 24-hour averages obtained at a central site monitor and summaries of the entire pregnancy and each trimester were calculated. The researchers looked at several pollutants, including carbon monoxide, nitrogen dioxide, ozone and particulate matter.

To calculate lung function growth, which is determined primarily by changes in lung capacity as a child grows, the researchers used spirometry, a technique which measures the volume and speed of air as it is exhaled from the lungs. For this study, multiple lung function tests were performed and significant changes were noted in four measurements: the FVC, or forced vital capacity, which reflects the volume of air that can be blown out after fully inhaling; the FEV1, or forced expiratory volume in 1 second, which is the volume of air that can forcibly be blown out in one second, after fully inhaling; the FEF, or forced expiratory flow, which reflects the flow of air coming out of the lungs during the middle portion of a forced exhalation; and the PEF, or peak expiratory flow, which is the maximal flow achieved when air is forcibly exhaled immediately after being inhaled.

Measurement models were performed separately for boys and for girls, and were adjusted for height, age, race and socioeconomic status.

At the conclusion of the study, the researchers found that exposure to nitrogen dioxideduring the first and second trimesters was associated with lower pulmonary function growth in both girls and boys in childhood. Among girls, exposure to nitrogen dioxide during the first trimester was associated with lower FEV1 growth and exposure to nitrogen dioxideduring the second trimester was associated with lower FEF growth. Among boys, nitrogen dioxide exposure during the first and second trimesters of pregnancy was associated with lower FVC growth. Exposure to particulate matter during the first trimester was associated with lower FEV1 and FVC growth in girls; similar exposures during the third trimester were associated with lower PEF and FEF growth among boys.

"This finding adds to the evidence that current air pollution levels continue to have adverse effects on human health," Dr. Padula said. "Few studies have examined prenatal exposure to air pollution and subsequent lung function in childhood. These results suggest that we need to be doing a better job to reduce traffic-related air pollution.

Dr. Padula said she and her colleagues hope to conduct future studies on the role of genetic susceptibility to air pollution.

"Currently, our studies are examining the associations between prenatal air pollution and adverse birth outcomes," she noted. "It would be useful to know what makes some people more or less susceptible to the adverse affects of air pollution so we might be able to provide more targeted public health advice."

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Pollution plays a role in autism and dyslexia, say Israeli and foreign scientists

Conclusions emerge from presentations by Israeli and foreign scientists at a conference on the relationship between pollution and children's health problems.

Growing evidence suggests pollution plays a significant role in developmental problems among children, including autism, attention deficit disorder and even dyslexia, it was revealed at a conference on the subject in Israel Wednesday.

These conclusions emerged from presentations by Israeli and foreign scientists at a conference on the relationship between pollution and children's health problems. The conference, sponsored by the Environment and Health Fund, was part of the annual convention of the Israel Ambulatory Pediatric Association.

One of the principal speakers at the conference was Prof. Philip Landrigan, a pediatrician at Mount Sinai Hospital in New York, who noted that many countries worldwide have reported a sharp rise in recent years in the prevalence of development disorders such as autism and ADD. This rise cannot be attributed solely to genetic factors or to higher rates of diagnosis, he said, and today, even researchers who once thought environmental factors could explain only a small fraction of the increased incidence of autism, for instance, have been convinced that it accounts for at least 25 percent of the rise.

Exposure to substances such as lead, mercury and pesticides is particularly dangerous for children, because they are more sensitive to these materials - in part because their brains are still developing, Landrigan said. A child's body also breaks down poisonous materials less efficiently than the adult body does, and any given quantity of chemical has more of an impact on a child because it constitutes a larger proportion of his body mass. Additionally, most children will spend more years being exposed to poisonous substances than adults will, he said.

Today, blood tests find hundreds of types of chemicals in children's blood, Landrigan noted. But little is known about the effects of most of these substances because they have never been studied. And while hundreds of other substances have been identified as harmful to human health, their impact on children in particular has generally not been investigated. Nor has research been done on the cumulative effect of exposure to multiple poisonous substances - though modern humanity makes use of some 80,000 different chemicals, he said.

Some Western countries have tried to contend with the problem by requiring chemical manufacturers to do more testing of and reporting on their products' health impact, but so far success has been partial.

Dr. Orna Metzner of the Environmental Protection Ministry said that Israel, too, is now working on creating a database for chemical safety data, as one of the commitments it undertook when it joined the OECD.

One of the successes of recent years has been in reducing children's exposure to lead. Dr. Tamar Berman, the Health Ministry's toxicologist, said the level of lead found in drinking water now exceeds the permitted maximum in only two percent of samples - though she stressed that, given the risks of lead exposure, this is still too much.

Read more: http://www.haaretz.com/print-edition/news/pollution-plays-a-role-in-autism-and-dyslexia-say-israeli-and-foreign-scientists-1.398829

Pollutants Linked to 450 Percent Increase in Risk of Birth Defects in Rural China

Pesticides and pollutants are related to a 450 percent increase in the risk of spina bifida and anencephaly in rural China, according to scientists at The University of Texas at Austin and Peking University.

Two of the pesticides found in high concentrations in the placentas of affected newborns and stillborn fetuses were endosulfan and lindane. Endosulfan is only now being phased out in the United States for treatment of cotton, potatoes, tomatoes and apples. Lindane was only recently banned in the United States for treatment of barley, corn, oats, rye, sorghum and wheat seeds.

Strong associations were also found between spina bifida and anencephaly and high concentrations of polycyclic aromatic hydrocarbons (PAHs), which are byproducts of burning fossil fuels such as oil and coal. Spina bifida is a defect in which the backbone and spinal canal do not close before birth. Anencephaly is the absence of a large part of the brain and skull.

"Our advanced industrialized societies have unleashed upon us a lot of pollutants," says Richard Finnell, professor of nutritional sciences and director of genomic research at the Dell Children's Medical Center of Central Texas. "We've suspected for a while that some of these pollutants are related to an increase in birth defects, but we haven't always had the evidence to show it. Here we quite clearly showed that the concentration of compounds from pesticides and coal-burning are much higher in the placentas of cases with neural tube defects than in controls."

The study, which was published in August in the Proceedings of the National Academy of Sciences, is the result of a more than decade-long collaboration between Finnell and a team of researchers in Shanxi, a province in northern China.

Finnell sought collaborators in China because the prevalence of neural tube defects is much greater there than it is in the United States. Also, because of its population policies, China is good at tracking births.

"It's an extraordinary natural experiment," says Finnell, who was recently recruited to the university to help anchor the Dell Pediatric Research Institute. "It would be much harder to do this study in the United States, where neural tube defects are more rare. It's also an opportunity to assist the Chinese government in their efforts to lower their birth defect rates."

Read more: http://www.sciencedaily.com/releases/2011/10/111019185134

Air pollution tied to raised risk of preemie birth

Traffic-related air pollution may put pregnant women at risk for a premature birth, according to a new study.

Researchers looked at 100,000 births among women in California who lived within five miles of an air quality monitoring station. The births spanned a 22-month period from June 2004.

Exposure to traffic-related air pollutants such as polycyclic aromatic hydrocarbons (PAH) was associated with up to a 30 percent greater risk of premature birth; exposure to ammonium nitrate fine particles was associated with a 21 percent increased risk, and exposure to benzene and fine particulate matter from diesel fumes was associated with a 10 percent higher risk, the University of California researchers found

The study is published online Oct. 6 in the journalEnvironmental Health

"Air pollution is known to be associated with low birth weight and premature birth. Our results show that traffic-related PAH are of special concern as pollutants, and that PAH sources besides traffic contributed to premature birth," Dr. Beate Ritz said in a journal news release.

"The increase in premature birth risk due to ammonium nitrate particles suggests secondary pollutants are also negatively impacting the health of unborn babies. To reduce the effects of these pollutants on public health, it is important that accurate modeling of local and regional spatial and temporal air pollution be incorporated into pollution policies," Ritz added.

Read more: http://yourlife.usatoday.com/health/story/2011-10-15/Traffic-related-pollution-may-imperil-pregnancies/50785508/1