Air pollution's connection to infant mortality

June 29, 2020

Science Daily/Stanford University

The study of sub-Saharan Africa finds that a relatively small increase in airborne particles significantly increase infant mortality rates. A cost-effective solution may lie in an exotic-sounding proposal.

Dust sweeping across the Southeast U.S. in recent days warns of a growing risk to infants and children in many parts of the world. A Stanford-led study focuses on this dust, which travels thousands of miles from the Sahara Desert, to paint a clearer picture than ever before of air pollution's impact on infant mortality in sub-Saharan Africa. The paper, published June 29 in Nature Sustainability, reveals how a changing climate might intensify or mitigate the problem, and points to seemingly exotic solutions to reducing dust pollution that could be more effective and affordable than current health interventions in improving child health.

"Africa and other developing regions have made remarkable strides overall in improving child health in recent decades, but key negative outcomes such as infant mortality remain stubbornly high in some places," said study senior author Marshall Burke, an associate professor of Earth system science in Stanford's School of Earth, Energy & Environmental Sciences. "We wanted to understand why that was, and whether there was a connection to air pollution, a known cause of poor health."

Understanding airborne danger

Children under 5 are particularly vulnerable to the tiny particles, or particulate, in air pollution that can have a range of negative health impacts, including lower birth weight and impaired growth in the first year of life. In developing regions, exposure to high levels of air pollution during childhood is estimated to reduce overall life expectancy by 4-5 years on average.

Quantifying the health impacts of air pollution -- a crucial step for understanding global health burdens and evaluating policy choices -- has been a challenge in the past. Researchers have struggled to adequately separate out the health effects of air pollution from the health effects of activities that generate the pollution. For example, a booming economy can produce air pollution but also spur developments, such as lower unemployment, that lead to better healthcare access and improved health outcomes.

To isolate the effects of air pollution exposure, the Stanford-led study focuses on dust carried thousands of miles from the Bodélé Depression in Chad -- the largest source of dust emissions in the world. This dust is a frequent presence in West Africa and, to a lesser extent, across other African regions. The researchers analyzed 15 years of household surveys from 30 countries across Sub-Saharan Africa covering nearly 1 million births. Combining birth data with satellite-detected changes in particulate levels driven by the Bodélé dust provided an increasingly clear picture of poor air quality's health impacts on children.

Sobering findings and surprising solutions

The researchers found that a roughly 25 percent increase in local annual mean particulate concentrations in West Africa causes an 18 percent increase in infant mortality. The results expand on a 2018 paper by the same researchers that found exposure to high particulate matter concentrations in sub-Saharan Africa accounted for about 400,000 infant deaths in 2015 alone.

The new study, combined with previous findings from other regions, makes clear that air pollution, even from natural sources, is a "critical determining factor for child health around the world," the researchers write. Emissions from natural sources could change dramatically in a changing climate, but it's unclear how. For example, the concentration of dust particulate matter across Sub-Saharan Africa is highly dependent on the amount of rainfall in the Bodélé Depression. Because future changes in rainfall over the Bodélé region due to climate change are highly uncertain, the researchers calculated a range of possibilities for sub-Saharan Africa that could result in anywhere from a 13-percent decline in infant mortality to a 12-percent increase just due to changes in rainfall over the desert. These impacts would be larger than any other published projections for climate change impact on health across Africa.

Safeguarding children against air pollution is nearly impossible in many developing regions because many homes have open windows or permeable roofs and walls, and infants and young children are unlikely to wear masks. Instead, the researchers suggest exploring the possibility of dampening sand with groundwater in the Bodélé region to stop it from going airborne -- an approach that has been successful at small scale in California.

The researchers estimate that deploying solar-powered irrigation systems in the desert area could avert 37,000 infant deaths per year in West Africa at a cost of $24 per life, making it competitive with many leading health interventions currently in use, including a range of vaccines and water and sanitation projects.

"Standard policy instruments can't be counted on to reduce all forms of air pollution," said study lead author Sam Heft-Neal, a research scholar at Stanford's Center on Food Security and the Environment. "While our calculation doesn't consider logistical constraints to project deployment, it highlights the possibility of a solution that targets natural pollution sources and yields enormous benefits at a modest cost."

https://www.sciencedaily.com/releases/2020/06/200629120215.htm

Air quality impacts early brain development

Study explores how living close to roadways may impact the brain

June 17, 2020

Science Daily/University of California - Davis

Researchers at the University of California, Davis, have found a link between traffic-related air pollution and an increased risk for changes in brain development relevant to neurodevelopmental disorders. Their study, based on rodent models, corroborates previous epidemiological evidence showing this association.

While air pollution has long been a concern for pulmonary and cardiovascular health, it has only been within the past decade that scientists have turned their attention to its effects on the brain, said UC Davis toxicologist Pamela Lein, senior author of the study, recently published in Translational Psychiatry.

Researchers had previously documented links between proximity to busy roadways and neurodevelopmental disorders such as autism, but preclinical data based on real-time exposures to traffic-related air pollution was scarce to nonexistent.

Lein worked with UC Davis atmospheric scientist Anthony Wexler and first author Kelley Patten, a doctoral student in the UC Davis graduate group for pharmacology and toxicology, to develop a novel approach to study the impacts of traffic-related air pollution in real time. They set up a vivarium near a traffic tunnel in Northern California so they could mimic, as closely as possible, the experience of humans in a rodent model.

"This approach was a creative way to get at the question of what impacts air pollution has on the brain in the absence of confounding factors such as socioeconomic influences, diet, etc.," Lein said. "It's important to know if living close to these roadways poses a significant risk to the developing human brain.

"If it does," Lein continues, "scientists can warn susceptible individuals, such as pregnant women -- particularly those who have already had a child diagnosed with a neurodevelopmental disorder -- to take appropriate precautions to minimize risks to the health of their child's brain."

EARLY EXPOSURE OUTCOMES 

The researchers compared the brains of rat pups exposed to traffic-related air pollution with those exposed to filtered air. Both air sources were drawn from the tunnel in real time.

They found abnormal growth and increased neuroinflammation in the brains of animals exposed to air pollution. This suggests that air pollution exposure during critical developmental periods may increase the risk for changes in the developing brain that are associated with neurodevelopmental disorders.

"What we witnessed are subtle changes," Patten said. "But we are seeing these effects using air pollution exposures that fall within regulatory limits. With the backdrop of other environmental and genetic risk factors in humans, this may have a more pronounced effect. This exposure also contains very fine particulate matter that isn't currently regulated."

In a separate study, Patten extended this exposure for 14 months to look at longer-term impacts of traffic-related air pollution and is in the process of writing up those results.

The team is also interested in what component of traffic-related air pollution is driving the neurodevelopmental outcomes.

If they can identify the culprits, Lein said, then scientists can approach legislators to develop scientifically based regulations to protect the developing human brain.

TEAM EFFORTS

UC Davis atmospheric scientist and co-author Keith Bein said that the single most challenging aspect of studying the health effects of air pollution may be replicating how, when and what people are exposed to throughout their lifetimes.

Tackling this requires creative thinking and a multidisciplinary team of researchers, including exposure engineers, atmospheric scientists, toxicologists, biologists, behaviorists and animal care specialists.

"We have managed to build a unique and talented team and taken advantage of our built environment to bring us closer than we've been before to achieving these objectives," Bein said. "Increasingly, these types of efforts are required to continue advancing the field, thereby informing policymakers and stakeholders about how best to protect human health."

Other study co-authors include: Eduardo González and Anthony Valenzuela, UC Davis School of Veterinary Medicine; Elizabeth Berg, UC Davis School of Medicine; Christopher Wallis, UC Davis Air Quality Research Center; Joel Garbrow, Washington University; and Jill Silverman at the UC Davis MIND Institute and School of Medicine. The study was supported by the National Institutes of Health.

https://www.sciencedaily.com/releases/2020/06/200617145934.htm

Mix of stress and air pollution may lead to cognitive difficulties in children

January 16, 2020

Science Daily/Columbia University's Mailman School of Public Health

Children with elevated exposure to early life stress in the home and elevated prenatal exposure to air pollution exhibited heightened symptoms of attention and thought problems, according to researchers at Columbia University Mailman School of Public Health and Columbia Psychiatry. Early life stress is common in youth from disadvantaged backgrounds who also often live in areas with greater exposure to air pollution.

Air pollution has negative effects on physical health, and recent work has begun to also show negative effects on mental health. Life stress, particularly early in life, is one of the best-known contributors to mental health problems. The new study is one of the first to examine the combined effects of air pollution and early life stress on school-age children. Results appear in the Journal of Child Psychology and Psychiatry.

"Prenatal exposure to polycyclic aromatic hydrocarbons, a neurotoxicant common in air pollution, seems to magnify or sustain the effects of early life social and economic stress on mental health in children," says first author David Pagliaccio, PhD, assistant professor of clinical neurobiology in psychiatry at Columbia Psychiatry.

"Air pollutants are common in our environment, particularly in cities, and given socioeconomic inequities and environmental injustice, children growing up in disadvantaged circumstances are more likely to experience both life stress and exposure to neurotoxic chemicals," says senior author Amy Margolis, PhD, assistant professor of medical psychology in psychiatry at Columbia Psychiatry.

"These exposures have a combined effect on poor mental health outcomes and point to the importance of public health programs that try to lessen exposure to these critical risk factors, to improve not only physical, but psychological health," says Julie Herbstman, PhD, associate professor of environmental health science and director of the Columbia Center for Children's Environmental Health at Columbia Mailman School of Public Health.

Data were from the CCCEH Mothers and Newborns longitudinal birth cohort study in Northern Manhattan and the Bronx, which includes many participants who self-identify as African American or Dominican. Mothers wore an air monitoring backpack during the third trimester of pregnancy to measure exposure to air pollutants in their daily lives. When their children were 5 years old, mothers reported on stress in their lives, including neighborhood quality, material hardship, intimate partner violence, perceived stress, lack of social support, and general distress levels. Mothers then reported on their child's psychiatric symptoms at ages 5, 7, 9 and 11.

The combined effect of air pollution and early life stress was seen across several measures of thought and attention problems/ADHD at age 11. (Thought problems included obsessive thoughts and behaviors or thoughts that others find strange.) The effects were also linked to PAH-DNA adducts -- a dose-sensitive marker of air pollution exposure.

The researchers say PAH and early life stress may serve as a "double hit" on shared biological pathways connected to attention and thought problems. Stress likely leads to wide-ranging changes in, for example, epigenetic expression, cortisol, inflammation, and brain structure and function. The mechanism underlying the effects of PAH is still being interrogated; however, alterations in brain structure and function represent possible shared mechanistic pathways.

Earlier studies making use of the same longitudinal cohort data found that prenatal exposure to air pollution combines with material hardship to significantly increase ADHD symptoms in children. A separate study found a combination of air pollution and poverty lowered child IQ.

https://www.sciencedaily.com/releases/2020/01/200116155436.htm

Air pollution in childhood linked to schizophrenia

January 7, 2020

Science Daily/Aarhus University

Air pollution affects physical health, and research results now conclude that it also affects our psychological health. The study, which combines genetic data from iPSYCH with air pollution data from the Department of Environmental Science, shows that children who are exposed to a high level of air pollution while growing up, have an increased risk of developing schizophrenia.

"The study shows that the higher the level of air pollution, the higher the risk of schizophrenia. For each 10 ?g/m3 (concentration of air pollution per cubic metre) increase in the daily average, the risk of schizophrenia increases by approximately twenty per cent. Children who are exposed to an average daily level above 25 ?g/m3 have an approx. sixty per cent greater risk of developing schizophrenia compared to those who are exposed to less than 10 ?g/m3," explains Senior Researcher Henriette Thisted Horsdal, who is behind the study.

To put these figures into perspective, the lifetime risk of developing schizophrenia is approximately two per cent, which equates to two out of a hundred people developing schizophrenia during their life. For people exposed to the lowest level of air pollution, the lifetime risk is just under two per cent, while the lifetime risk for those exposed to the highest level of air pollution is approx. three per cent.

Unknown cause

The results of the study have just been published in the scientific journal JAMA Network Open.

"The risk of developing schizophrenia is also higher if you have a higher genetic liability for the disease. Our data shows that these associations are independent of each other. The association between air pollution and schizophrenia cannot be explained by a higher genetic liability in people who grow up in areas with high levels of air pollution," says Henriette Thisted Horsdal about the study, which is the first of its kind to combine air pollution and genetics in relation to the risk of developing schizophrenia.

The study included 23,355 people in total, and of these, 3,531 developed schizophrenia. Though the results demonstrate an increased risk of schizophrenia when the level of air pollution during childhood increases, the researchers cannot comment on the cause. Instead they emphasise that further studies are needed before they can identify the cause of this association.

https://www.sciencedaily.com/releases/2020/01/200107104913.htm

Is pollution linked to psychiatric disorders?

August 20, 2019

Science Daily/PLOS

Researchers are increasingly studying the effects of environmental insults on psychiatric and neurological conditions, motivated by emerging evidence from environmental events like the record-breaking smog that choked New Delhi two years ago. The results of a new study publishing August 20 in the open-access journal PLOS Biology by an international group of researchers using large data sets from the US and Denmark suggests a possible link between exposure to environmental pollution and an increase in the prevalence of psychiatric disorders.

The team found that poor air quality was associated with higher rates of bipolar disorder and major depression in both US and Danish populations. The trend appeared even stronger in Denmark, where exposure to polluted air during the first ten years of a person's life also predicted a more than two-fold increase in schizophrenia and personality disorders.

"Our study shows that living in polluted areas, especially early on in life, is predictive of mental disorders in both the United States and Denmark," said computational biologist Atif Khan, the first author of the new study. "The physical environment -- in particular air quality -- warrants more research to better understand how our environment is contributing to neurological and psychiatric disorders."

Although mental illnesses like schizophrenia develop due to a complex interplay of genetic predispositions and life experiences or exposures, genetics alone do not account entirely for variations in mental health and disease. Researchers have long suspected that genetic, neurochemical and environmental factors interact at different levels to affect the onset, severity and progression of these illnesses.

Growing evidence is beginning to provide insight into how components of air pollution can be toxic to the brain: Recent studies on rodents suggest that environmental agents like ambient small particulate matter (fine dust) travel to the brain through the nose and lungs, while animals exposed to pollution have also shown signs of cognitive impairment and depression-like behavioral symptoms. "We hypothesized that pollutants might affect our brains through neuroinflammatory pathways that have also been shown to cause depression-like signs in animal studies," said Andrey Rzhetsky, who led the new study.

To quantify air pollution exposure among individuals in the United States, the University of Chicago team relied on the US Environmental Protection Agency's measurements of 87 air quality measurements. For individuals in Denmark, they used a national pollution register that tracked a smaller number of pollutants with much higher spatial resolution.

The researchers then examined two population data sets, the first being a U.S. health insurance claims database that included 11 years of claims for 151 million individuals. The second dataset consisted of all 1.4 million individuals born in Denmark from 1979 through 2002 who were alive and residing in Denmark at their tenth birthday. Because Danes are assigned unique identification numbers that can link information from various national registries, the researchers were able to estimate exposure to air pollution at the individual level during the first ten years of their life. In the US study, exposure measurements were limited to the county level. "We strived to provide validation of association results in independent large datasets," said Rzhetsky.

The findings have not been without controversy. "This study on psychiatric disorders is counterintuitive and generated considerable resistance from reviewers," said Rzhetsky. Indeed, the divided opinions of the expert reviewers prompted PLOS Biology to commission a special companion article from Prof. John Ioannidis of Stanford University (Ioannidis is unconnected with the study, but assisted the journal with the editorial process).

"A causal association of air pollution with mental diseases is an intriguing possibility. Despite analyses involving large datasets, the available evidence has substantial shortcomings and a long series of potential biases may invalidate the observed associations," says Ioannidis in his commentary. "More analyses by multiple investigators, including contrarians, are necessary."

Rzhetsky also cautioned that the significant associations between air pollution and psychiatric disorders discovered in the study do not necessarily mean causation, and said that further research is needed to assess whether any neuroinflammatory impacts of air pollution share common pathways with other stress-induced conditions.

https://www.sciencedaily.com/releases/2019/08/190820141604.htm

Exposure to air pollution before and after birth may affect fundamental cognitive abilities

May 23, 2019

Science Daily/Barcelona Institute for Global Health (ISGlobal)

A growing body of research suggests that exposure to air pollution in the earliest stages of life is associated with negative effects on cognitive abilities. A new study led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by "la Caixa," has provided new data: exposure to particulate matter with a diameter of less than 2.5 μm (PM2.5) during pregnancy and the first years of life is associated with a reduction in fundamental cognitive abilities, such as working memory and executive attention.

The study, carried out as part of the BREATHE project, has been published in Environmental Health Perspectives. The objective was to build on the knowledge generated by earlier studies carried out by the same team, which found lower levels of cognitive development in children attending schools with higher levels of traffic-related air pollution.

The study included 2,221 children between 7 and 10 years of age attending schools in the city of Barcelona. The children's cognitive abilities were assessed using various computerized tests. Exposure to air pollution at home during pregnancy and throughout childhood was estimated with a mathematical model using real measurements.

The study found that greater PM2.5 exposure from pregnancy until age 7 years was associated with lower working memory scores on tests administered between the ages of 7 and 10 years. The results suggest that exposure to fine particulate matter throughout the study period had a cumulative effect, although the associations were stronger when the most recent years of exposure were taken into account. Working memory is a cognitive system responsible for temporarily holding information for subsequent manipulation. It plays a fundamental role in learning, reasoning, problem-solving and language comprehension.

Sex-stratified analysis showed that the relationship between PM2.5 exposure and diminished working memory was found only in boys. "As yet, we don't understand what causes these differences, but there are various hormonal and genetic mechanisms that could lead to girls having a better response to inflammatory processes triggered by fine particulate matter and being less susceptible to the toxicity of these particles," commented Ioar Rivas, ISGlobal researcher and lead author of the study.

The study also found that higher exposure to particulate matter was associated with a reduction in executive attention in both boys and girls. Executive attention is one of the three networks that make up a person's attention capacity. It is involved in high-level forms of attention, such as the detection and resolution of conflicts between options and responses, error detection, response inhibition, and the regulation of thoughts and feelings.

Whereas previous studies in the BREATHE project analysed exposure to air pollution at schools over the course of a year, this study assessed exposures at the participants' homes over a much longer time: from the prenatal period to 7 years of age.

"This study reinforces our previous findings and confirms that exposure to air pollution at the beginning of life and throughout childhood is a threat to neurodevelopment and an obstacle that prevents children from reaching their full potential," commented Jordi Sunyer, Childhood and Environment Programme Coordinator at ISGlobal and last author of the study.

https://www.sciencedaily.com/releases/2019/05/190523104925.htm

Study uncovers link between air pollution and intellectual disabilities in children

November 21, 2018

Science Daily/Wiley

British children with intellectual disabilities are more likely than their peers to live in areas with high outdoor air pollution, according to a new study.

The findings come from an analysis of data extracted from the UK's Millennium Cohort Study, a nationally representative sample of more than 18,000 UK children born in 2000 to 2002.

Averaging across ages, children with intellectual disabilities were 33 percent more likely to live in areas with high levels of diesel particulate matter, 30 percent more likely to live in areas with high levels of nitrogen dioxide, 30 percent more likely to live in areas with high levels of carbon monoxide, and 17 percent more likely to live in areas with high levels of sulphur dioxide.

The authors note that intellectual disability is more common among children living in more socio-economically deprived areas, which tend to have higher levels of air pollution; however, exposure to outdoor air pollution may impede cognitive development, thereby increasing the risk of intellectual disability.

"We know that people with intellectual disabilities in the UK have poorer health and die earlier than they should. This research adds another piece to the jigsaw of understanding why that is the case and what needs to be done about it," said lead author Dr. Eric Emerson, of The University of Sydney, in Australia.

https://www.sciencedaily.com/releases/2018/11/181121073250.htm