Kids living near major roads at higher risk of developmental delays
April 9, 2019
Science Daily/NIH/Eunice Kennedy Shriver National Institute of Child Health and Human Development
Young children who live close to a major roadway are twice as likely to score lower on tests of communications skills, compared to those who live farther away from a major roadway, according to an analysis by researchers at the National Institutes of Health and the University of California, Merced. Moreover, children born to women exposed during pregnancy to higher-than-normal levels of traffic-related pollutants -- ultra-fine airborne particles and ozone -- had a small but significantly higher likelihood of developmental delays during infancy and early childhood. The study appears in Environmental Research.
"Our results suggest that it may be prudent to minimize exposure to air pollution during pregnancy, infancy, and early childhood -- all key periods for brain development," said Pauline Mendola, Ph.D., an investigator in the Division of Intramural Population Health Research at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and the study's senior author.
Previous studies have linked exposure to common air pollutants in pregnancy to low birthweight, preterm birth and stillbirth. A few studies have found a higher risk of autism and of lower cognitive functioning in children living near freeways, but results of studies about how prenatal and early childhood exposure to air pollution might affect development have been inconsistent.
Given that a large proportion of the U.S. population lives close to major roadways, which are major sources of air pollution, the researchers sought to determine if living near heavily traveled roads was linked to lower scores on developmental screens -- questionnaires or checklists that indicate whether a child is developing normally or needs to be referred to a specialist for further testing.
The researchers analyzed data from the Upstate KIDS Study. They matched the addresses of 5,825 study participants to a roadway data set, calculating the distance of each address to the nearest major roadway. For each participant, they matched home address, mother's work address during pregnancy, and address of the child's day care location to an Environmental Protection Agency data set for estimating air pollution levels. From 8 months to 36 months of age, the children were screened every 4 to 6 months with the Ages and Stages Questionnaire, a validated screening measure evaluating five domains of child development: fine motor skills, large motor skills, communication, personal social functioning and problem-solving ability.
Compared to children living more than half a mile from a major roadway, children living from roughly 164 feet to .3 miles from a major roadway were twice as likely to have failed at least one screen of the communications domain.
The researchers also estimated exposures to ozone and fine inhalable particles (PM2.5), two pollutants produced by car traffic. Fine inhalable particles are 30 times smaller than the width of a human hair, can pass through the lungs' defenses, and are absorbed directly into the bloodstream.
Prenatal exposure to elevated PM2.5 led to a 1.6 to 2.7 percent higher risk of failing any developmental domain, while higher ozone exposure led to a .7 to 1.7 percent higher risk of failing a developmental domain. In contrast, higher postnatal exposure to ozone was linked to a 3.3 percent higher risk of failing most domains of the developmental screen at 8 months, a 17.7 percent higher risk of overall screening failure at 24 months, and a 7.6 percent higher risk of overall screening failure at 30 months.
These results led the researchers to conclude that early childhood exposure to air pollutants may convey a higher risk for developmental delays, compared to similar exposures in the womb. The study is associational and so cannot prove cause and effect. The authors noted that larger studies are necessary to confirm these links.
"It is not clear why exposure to pollutants after birth is linked to a higher risk of developmental delay," said Sandie Ha, Ph.D., of the Department of Public Health at the University of California, Merced, and lead author of the study. "However, unlike exposure during pregnancy, exposure during childhood is more direct and does not go through a pregnant woman's defenses."
https://www.sciencedaily.com/releases/2019/04/190409164002.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
Exposure to air pollution in pregnancy does not increase symptoms of attention-deficit
June 25, 2018
Science Daily/Barcelona Institute for Global Health (ISGlobal)
A study of 30,000 children from seven European countries found no association between prenatal exposure to air pollution and symptoms of attention-deficit and hyperactivity.
Exposure to air pollution during pregnancy may not be associated with an increased risk of attention-deficit and hyperactivity symptoms in children aged 3 to 10 years. This was the conclusion of a new study led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the "la Caixa" Banking Foundation. The study included data on nearly 30,000 children from seven European countries.
With a worldwide prevalence of 5%, ADHD is the most common childhood behavioural disorder. ADHD is characterized by a pattern of inattention, hyperactivity and/or impulsivity that is atypical for the child's age. These symptoms can interfere with development and have been associated with academic problems in school-aged children as well as an increased risk of problems with addiction or risky behaviours.
Recent studies have concluded that prenatal exposure to air pollution could affect brain development in children, but the evidence on the effects of air pollution on ADHD symptoms is limited.
The new study, published in the journal Epidemiology, forms part of the European Study of Cohorts for Air Pollution Effects (ESCAPE). It included 30,000 children between 3 and 10 years of age from eight birth cohorts in Germany, Denmark, France, Italy, the Netherlands, Sweden and Spain (the latter consisting of four sub-cohorts from the INMA project in Gipuzkoa, Granada, Sabadell and Valencia). The study estimated exposures to nitrogen oxides (NOx) and particulate matter (PM10 and PM2.5) throughout pregnancy at each participant's home address. ADHD symptoms were assessed using various questionnaires completed by parents and/or teachers.
Joan Forns, lead author of the study, commented: "Our findings show no association between exposure to air pollution during pregnancy and increased risk of ADHD symptoms."
"Given the conclusions of this study and the inconsistent findings of previous studies, we hypothesise that exposure to air pollution might not increase the risk of ADHD in children in the general population," explained ISGlobal researcher Mònica Guxens, who coordinated the study. "However, we believe that exposure to air pollution could have harmful effects on neuropsychological development, especially in genetically susceptible children."
It has been shown that ADHD is the result of complex interactions between genetic background (heritability is approximately 75%), environmental factors and social determinants. "We will continue to study the role of air pollution in order to rule out its association with childhood ADHD and improve our understanding of what causes this disorder," said Guxens.
https://www.sciencedaily.com/releases/2018/06/180625122348.htm