ECHO Cohort Study Finds No Significant Evidence that Prenatal Cannabis Exposure Increases Likelihood of Child Autism Spectrum Disorder

Authors: Chaela Nutor, Patricia A. Brennan, et al.

Who sponsored this study?

This research was supported by the Environmental influences on Child Health Outcomes (ECHO) Program, Office of The Director, National Institutes of Health.

Why was this study needed?

With the legalization of cannabis in some areas of the U.S., there has been a decrease in the perception of risk and an increase in cannabis use among pregnant women. While fetal exposure to cannabis has been linked to poorer neonatal and cognitive outcomes, relatively few studies have examined the association between prenatal cannabis exposure and neurodevelopmental outcomes, including autism spectrum disorder (ASD).

What were the study results?

The investigators found no evidence that prenatal cannabis exposure increased the likelihood for ASD in the group of children included in the study. There was also no evidence that child sex or gestational age at birth affected how prenatal cannabis exposure related to likelihood of ASD. No other aspects of brain or child development were evaluated in the study.

Note: Results reported here are for a single study. Other or future studies may provide new information or different results. You should not make changes to your health without first consulting your healthcare professional.

What was this study's impact?

Although no significant associations were found with ASD outcomes in this study, other studies have found that prenatal cannabis exposure may still be associated with ASD traits or other facets of child development and behavior that were outside of the scope of this study.

Who was involved?

This study included 11,570 school-age children from 34 ECHO Cohort research sites across the U.S., including three sites that enrolled children with a higher likelihood of ASD and three sites that enrolled children from neonatal intensive care units (NICU).

What happened during the study?

ECHO Cohort researchers gathered data on cannabis use during pregnancy directly from mothers and indirectly from their medical records. They also collected information on ASD diagnosis, as well as caregiver-reported data on the children’s autism-related traits from the ages of 1 to 18 years. The researchers used this information to test whether prenatal cannabis use might be associated with ASD.

What happens next?

The researchers are planning another large national study to further examine the relationship between prenatal cannabis exposure and autism traits. Other work could examine whether exposure to cannabis in utero alters brain functioning.

Where can I learn more?

Access the full journal article, titled “Examining the Association Between Prenatal Cannabis Exposure and Child Autism Behaviors: A Multi-cohort Investigation in the Environmental influences on Child Health Outcomes (ECHO) Program," in Autism Research.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published August 2024

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ECHO Cohort Study Finds No Significant Evidence that Prenatal Cannabis Exposure Increases Likelihood of Child Autism Spectrum Disorder

New ECHO Cohort Research Suggests No Significant Association Between Prenatal Cannabis Exposure and Child Autism-Related Outcomes

Posted on August 27, 2024March 31, 2025 by Jodi Snare

Collaborative ECHO research led by Chaela Nutor, MA and Patricia A. Brennan, PhD of Emory University investigates the association between prenatal cannabis exposure and autism spectrum disorder (ASD). The study looked at data from 11,570 school-aged children from across the United States and found no evidence that prenatal cannabis exposure increases the likelihood of ASD, regardless of the child’s sex or gestational age at birth. This research, titled “Examining the Association Between Prenatal Cannabis Exposure and Child Autism Traits: A Multi-cohort Investigation in the Environmental influences on Child Health Outcomes (ECHO) Program,” is published in Autism Research.

This study included children and their mothers from 34 ECHO cohorts across the United States. ECHO researchers gathered data on cannabis use during pregnancy directly from mothers and from their medical records. They also collected information on ASD diagnosis, as well as caregiver-reported data on the children’s autism traits when the children were 1 to 18 years. The researchers used these data and reports to test whether prenatal cannabis use might be associated with ASD.

“With the legalization of cannabis in some areas of the United States, there has been a decrease in the perception of risk and an increase in cannabis use among pregnant women,” said Chaela Nutor. “While fetal exposure to cannabis has been linked to poorer neonatal and cognitive outcomes, relatively few studies have tested the association between prenatal cannabis exposure and autism spectrum disorder.”

The results of this study supported the findings from previous studies showing that initial unadjusted associations between prenatal cannabis exposure and ASD behaviors in school-aged children are no longer significant when controlling for other factors, such as maternal use of other substances during pregnancy.

The researchers are planning another large national study to further investigate the relationship between prenatal cannabis exposure and autism-related behaviors. Future work could examine the role of continued exposure to cannabis after mothers are aware of pregnancy, and other studies could investigate combined exposure to tobacco and cannabis and associated risk for ASD.

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ECHO Researchers Investigate Association of Early Childhood Phthalate Exposures with ADHD Behaviors in Childhood and Adolescence

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ECHO Researchers Investigate Association of Early Childhood Phthalate Exposures with ADHD Behaviors in Childhood and Adolescence

Authors: Jiwon Oh, Julie B. Schweitzer, Deborah H. Bennett, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health, supported this research.

Why was this study needed?

Phthalates are widely used chemicals found in many everyday items such as food packaging, flooring, building materials, medicine coatings, medical supplies, cosmetics, and personal care products. When phthalates enter the body, they are metabolized and converted into various smaller molecules, known as metabolites.

Animal studies suggest that exposure to phthalates during early life may negatively affect the nervous system, but there has been limited investigation into potential associations between early childhood phthalate exposure and attention-deficit/hyperactivity disorder (ADHD) behaviors in later childhood and adolescence.

For this study, ECHO researchers wanted to investigate whether exposure to phthalates in children at ages 2-5 years was associated with ADHD symptoms when these children were ages 8-18 years.

Learn how to say phthalate.

What were the study results?

ECHO Cohort researchers evaluated the levels of several metabolites that result from phthalate exposure. They saw that in children ages 2-5 years, most of these molecules were not associated with ADHD behaviors in these children at ages 8-18 years.

However, among children who had been diagnosed with autism spectrum disorder (ASD), one of these metabolites—mono-2-heptyl phthalate (MHPP)—was associated with more ADHD behaviors. Among typically developing children, a different small molecule—mono-carboxy isooctyl phthalate (MCiOP)—was associated with more hyperactive/impulsive behaviors.

What was this study's impact?

This study suggests that early childhood exposure to certain phthalates may be associated with having both ASD and ADHD traits. Since ADHD behaviors are more commonly found in children with ASD, deepening the understanding of how exposure to environmental chemicals, such as phthalates, could contribute to this comorbidity may be important for managing and treating these conditions effectively.

Note: The results reported here are from a single study. Other or future studies may provide new information or different results. You should consult with a qualified healthcare provider for diagnosis and for answers to your personal questions.

Who was involved?

This study included 243 children living in Northern California and taking part in the ReCHARGE (Revisiting Childhood Autism Risks from Genetics and Environment) study. This study included both neurotypical and neurodiverse children, with about 60% of them having ever had neurodevelopmental concerns. Therefore, the children included in the study tended to have more ADHD behaviors compared with children in the general population.

What happened during the study?

Phthalate metabolites can be measured in biological samples, such as urine, to assess exposure to phthalates. In this study, the researchers measured 15 phthalate metabolites in urine samples of young children ages 2-5 years. Parents answered questions about each child’s ADHD symptoms at ages 8-18 years.

What happens next?

While the metabolite MHPP and the phthalate it’s derived from, di-n-heptyl phthalate (DHPP), are commonly found in children’s urine, their influence on neurodevelopment has not been studied as much as other phthalates. Since exposure to DHPP has been linked to problems with development and behavior in animals, further studies need to look more closely at this compound to understand its effects on how the brain develops in children.

Where can I learn more?

Read the full research article, titled “Early childhood exposures to phthalates in association with attention-deficit/hyperactivity disorder behaviors in middle childhood and adolescence in the ReCHARGE study,” in the journal International Journal of Hygiene and Environmental Health.

Learn more about ECHO’s other chemical exposure research.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published June 2024

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ECHO Researchers Investigate Association of Early Childhood Phthalate Exposures with ADHD Behaviors in Childhood and Adolescence

No Significant Correlation Found Between Labor-inducing Drug During Childbirth and Future Risk of ADHD and Autism Spectrum Disorder in Children, Study Finds

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No Significant Correlation Found Between Labor-Inducing Drug During Childbirth and Future Risk of ADHD and Autism Spectrum Disorder in Children, Study Finds

Synthetic oxytocin was associated with lower ADHD risk among children born to mothers with pre-pregnancy obesity. Mothers with pre-pregnancy obesity were more inclined to receive labor-inducing medication.

Authors: Lisa Kurth, PhD, et al.

Who sponsored this study?

This research was supported by the Environmental influences on Child Health Outcomes (ECHO) Program, Office of The Director, National Institutes of Health.

Why was this study needed?

More than 50% of U.S. childbirths are assisted with synthetic oxytocin (sOT)—known by trade names such as Pitocin or Syntocinon—a drug that promotes labor by stimulating the muscles in the uterus to contract. As rates of child ADHD and autism spectrum disorder (ASD) diagnoses are steadily rising, researchers have attempted to identify risk factors that might be contributing to these increases. There have been conflicting results from previous studies investigating the link between sOT exposure and childhood risk of ADHD and ASD. Additionally, the potential effect of the mother’s pre-pregnancy body mass index (BMI) on this association has not yet been studied.

What were the study results?

Analysis of data from a large and diverse ECHO Cohort sample suggests that maternal exposure to sOT during childbirth was not associated with an increased risk for ADHD or ASD in offspring. Associations did not differ by sex. Unexpectedly, sOT was associated with lower ADHD risk among children born to mothers with pre-pregnancy obesity.

The study also found that 48% of laboring mothers received sOT. Researchers saw slightly higher usage of sOT in mothers with pre-pregnancy obesity.

What was this study's impact?

The findings raise questions about how these drugs might affect health outcomes, especially when combined with maternal obesity during pregnancy. Additionally, the findings indicate that maternal obesity may influence the need for interventions during childbirth. These results do not currently support a need to modify the clinical use of sOT during childbirth.

What happened during the study?

A team of researchers used statistical analysis to examine the association between sOT exposure during labor and child ADHD or ASD diagnosis. Investigators also evaluated whether maternal pre-pregnancy BMI and child sex affected this correlation.

Note: Results reported here are for a single study. Other or future studies may provide new information or different results. You should not make changes to your health without first consulting your healthcare professional.

Who was involved?

This study included over 12,000 mother-child pairs from 44 ECHO Cohort research sites across the U.S. Of the mothers participating in this study, 48% were exposed to sOT during childbirth.

What happens next?

More research is needed to evaluate if the dosage and duration of sOT has any influence on children's neurodevelopment. Future studies may clarify how environmental exposures and other contributing factors, such as delivery method and maternal obesity at delivery, influence a child’s neurodevelopment. Examining maternal/fetal biospecimens could also reveal how this exposure affects mothers and babies.

Where can I learn more?

Access the full journal article, titled “Intrapartum Exposure to Synthetic Oxytocin, Maternal BMI, and Neurodevelopmental Outcomes in Children within the ECHO Consortium” in the Journal of Neurodevelopmental Disorders.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published May 26, 2024

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No Significant Correlation Found Between Labor-Inducing Drug During Childbirth and Future Risk of ADHD and Autism Spectrum Disorder in Children, Study Finds

ECHO Cohort Study Finds Association Between PFAS and Bioactive Lipids

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ECHO Cohort Study Finds Association Between PFAS and Bioactive Lipids

Authors: Himal Suthar, Max Aung, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Per- and polyfluoroalkyl substances (PFAS) are a large, complex group of synthetic chemicals that have been used in consumer products around the world since about the 1950s. They are ingredients in various everyday products. For example, PFAS are used to keep food from sticking to packaging or cookware, make clothes and carpets resistant to stains, and create firefighting foam that is more effective. People are most likely exposed to these chemicals by consuming PFAS-contaminated water or food, using products made with PFAS, or breathing air containing PFAS.

Because PFAS break down slowly, if at all, people and animals are repeatedly exposed to them, and blood levels of some PFAS can build up over time. Scientific studies have identified multiple health effects associated with PFAS exposure.[1] Women exposed to PFAS during pregnancy are at increased risk for adverse birth outcomes and pregnancy complications.

Lipids are fatty molecules that perform a variety of functions in the body—from forming the membranes of cells to serving as a building block for certain hormones. Changes in bioactive lipids—broadly defined as a category of lipids with signaling properties that cause biological effects and changes in the body—have been linked to PFAS exposure and adverse pregnancy outcomes. This study aimed to compare the concentration of PFAS in the blood of pregnant participants with levels of bioactive lipids in three important metabolic pathways.

[1] National Institute of Environmental Health Sciences: Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) (nih.gov)

What were the study results?

The research team analyzed the associations between 12 types of PFAS, in pairs and as mixtures, and 50 bioactive lipids in blood plasma in pregnant participants across three ECHO Cohort Study Sites. When researchers looked at data from different study sites, they found that higher levels of PFAS in blood were often linked with higher levels of certain bioactive lipids. The research team also noticed differences in the distribution of bioactive lipid compounds between individual study sites, possibly driven by variations in the genetic makeup and sociodemographic characteristics of the populations or differences in environmental exposures due to diet.

Footnote: Results reported here are for a single study and reflect an observed correlation. Other or future studies may provide new information or different results. You should always consult with a qualified healthcare provider for diagnosis and for answers to your personal questions.

What was this study's impact?

The similarity of results researchers found from the analysis of mixtures of PFAS chemicals and individual PFAS chemicals indicate that specific bioactive lipids could be useful biomarkers of PFAS exposure. Biomarkers are biological indicators of a particular health effect or status – in this case, PFAS exposure. They can be found in blood, urine, or other body fluids and can be substances, characteristics, genes, or proteins. This insight could help in understanding and addressing the health effects of PFAS by expanding screening methods.

The bioactive lipids measured in this study have not yet been tested as routine biomarkers in clinical settings. However, these findings aid in advancing the future of healthcare as additional and more complex lipid biomarkers become measurable and are tested for clinical use.

These findings encourage researchers to prioritize the study of PFAS and bioactive lipids pairs in future testing in addition to individually studying the effect of different types of PFAS. Additionally, this study highlights the importance of regulating the 12 types of PFAS observed.

Who was involved?

This study included 414 pregnant participants from three ECHO Cohort study sites: Chemicals in Our Bodies based in San Francisco, ECHO-PROTECT based in Puerto Rico, and Illinois Kids Development Study based in Chicago.

What happened during the study?

The research team estimated associations between prenatal PFAS exposure and bioactive lipids, measuring the levels of 12 types of PFAS and 50 bioactive lipids in 414 pregnant participants. Researchers quantified associations by using various statistical analyses while controlling for several factors (e.g., maternal age, gestational age at sample collection, maternal education, pre-pregnancy BMI).

What happens next?

The researchers plan to measure associations between bioactive lipids and peri- and prenatal mental health outcomes including perinatal and postpartum depression. Future studies could also look at the influence of other variables on this relationship. For example, researchers could investigate the influence of diet, which has been linked to changes in both PFAS and bioactive lipid concentrations.

Where can I learn more?

Access the full journal article, titled “Cross-Sectional Associations between Prenatal Per- and Poly-Fluoroalkyl Substances and Bioactive Lipids in Three Environmental Influences on Child Health Outcomes (ECHO) Cohorts,” in Environmental Science and Technology.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published May 14, 2024

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ECHO Cohort Study Finds Association Between PFAS and Bioactive Lipids

ECHO Study Investigates Relationship Between Phthalate Exposure and High Blood Pressure, Related Complications During Pregnancy

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ECHO Study Investigates Relationship Between Phthalate Exposure and High Blood Pressure, Related Complications During Pregnancy

Authors: John Meeker, Jordan Kuiper, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

High blood pressure during pregnancy, which can develop into the more serious conditions of preeclampsia* or eclampsia*, can pose significant health risks to pregnant women and their children. Potential environmental risk factors for ongoing high blood pressure during pregnancy and more severe pregnancy complications like preeclampsia or eclampsia have not been well-studied. Phthalates are chemicals used in various products, including plastics, personal care products, and food packaging. There is evidence, though limited, that exposure to some phthalates may be associated with preeclampsia and ongoing high blood pressure during pregnancy.

*Preeclampsia and eclampsia are pregnancy-related high blood pressure disorders. In preeclampsia, the mother’s high blood pressure reduces the blood supply to the fetus, which may get less oxygen and fewer nutrients. Eclampsia is when pregnant women with preeclampsia develop seizures or coma.

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What were the study results?

The researchers evaluated phthalate exposure by measuring urine levels of certain metabolites, which are small molecules the body makes when it breaks down foods, drugs, chemicals, or its own tissues (for example, fat or muscle tissue). This study found that higher levels of these metabolites were associated with a higher risk of developing preeclampsia, eclampsia, and/or ongoing high blood pressure during pregnancy. For example, a doubling of mono (3-carboxypropyl) phthalate (MCPP)—a metabolite linked to phthalates found in PVC-based plastics and insect repellents—was associated with 12% increased risk of developing preeclampsia or eclampsia.

For combined exposures, researchers divided participants into four groups, or quartiles, by increasing level of exposure. A quartile increase in the combined phthalate mixture was associated with a 27% increased risk of preeclampsia or eclampsia. This effect was generally larger among pregnant participants carrying female fetuses.

What was this study's impact?

The findings of this study suggest that exposure to certain phthalates found in plastics and other consumer products may be associated with pregnancy complications like gestational hypertension or preeclampsia.

Who was involved?

The study included data from 3,430 participants from eight ECHO sites across the U.S. which enrolled pregnant participants from 1999 to 2019.

What happened during the study?

The researchers measured the levels of 13 metabolites linked to phthalate exposure in urine samples collected at least once during pregnancy. They then evaluated the association between individual phthalates, as well as the combined mixture of phthalates, with the risk of developing preeclampsia, eclampsia, or ongoing high blood pressure during pregnancy.

Note: Results reported here are for a single study. Other or future studies may provide new information or different results. You should not make changes to your health without first consulting your healthcare professional.

What happens next?

Additional well-designed studies are needed to better understand the association between phthalate exposure and high blood pressure during pregnancy, the underlying biological mechanisms, and effective interventions that could reduce the risk of these kinds of pregnancy complications.

Where can I learn more?

Access the full journal article, titled “Urinary concentrations of phthalate metabolites in relation to preeclampsia and other hypertensive disorders of pregnancy in the Environmental influences on Child Health Outcomes (ECHO) program,” in Environment International.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published May, 2024

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ECHO Study Investigates Relationship Between Phthalate Exposure and High Blood Pressure, Related Complications During Pregnancy

Study Finds Link Between Phthalate Exposure During Pregnancy and Development of Multiple Health Outcomes in Children

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Study Finds Link Between Phthalate Exposure During Pregnancy and Development of Multiple Health Outcomes in Children

Authors: Drew Day, Kaja Z. LeWinn, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Chronic health conditions, such as asthma and obesity, can develop together during childhood but are usually studied separately. ECHO researchers used new machine learning tools to explore patterns of health outcomes in children and then looked at how common exposures are associated with multiple health conditions.

The goal of this study was to use data from ECHO Cohort research sites across six U.S. cities to characterize “clusters,” or patterns of obesity-related, lung health, and brain development outcomes in children and to investigate how these patterns relate to mothers’ exposures to chemicals called phthalates during pregnancy. Phthalates are chemicals widely used in plastics, and maternal exposure to certain phthalates have been linked to preterm birth.

What were the study results?

The researchers identified three groups of children with a pattern of health outcomes that occurred together:

A group of relatively healthy children;
A group of children with lower IQ, elevated obesity,
and slightly elevated asthma-related outcomes such as asthma, wheezing, and allergies; and
Another group of children with high asthma-related outcomes along with elevated obesity and some increase in anxiety- and depression-related outcomes.

Compared to children in the healthy group, other groups had more male children, mothers with higher BMI and lower education attainment, and lower household incomes. The researchers found that children—particularly boys—were more likely to be in the third group if their mothers were exposed to phthalates during pregnancy.

What was this study's impact?

These findings suggest that exposure to phthalates during pregnancy might be associated with an increased risk of developing not only asthma and related lung outcomes, but also obesity and mental health issues such as anxiety and depression. This study also suggests that low-income households are at higher risk for worse childhood health outcomes.

The three patterns of health outcomes seen in this study also reveal more about how pediatric diseases might arise together, which could help inform future research on what biological processes contribute to those health outcome patterns as well as better treatments and interventions to enhance child health.

Who was involved?

Researchers looked at health outcomes in 1,092 children across six U.S. cities. Researchers were able to collect measurements of phthalate exposure during pregnancy from 856 of these children’s mothers.

What happened during the study?

The researchers measured 15 health outcomes in children between the ages of 4 and 9 years—including body mass index (BMI), IQ, anxiety, depression, irritability, learning disabilities, speech problems, asthma, wheeze, and nasal allergies. The researchers evaluated how children developed multiple outcomes and investigated how the probability of being in a particular group was affected by exposure to 15 plastic-associated phthalate chemicals during pregnancy. The researchers measured phthalate exposure during pregnancy using urine samples collected from 2007–2014 from mothers during late pregnancy.

Note: Results reported here are for a single study. Other or future studies may provide new information or different results. You should not make changes to your health without first consulting your healthcare professional.

What happens next?

This study’s multi-outcome approach can be used in future studies to identify public health risks that may affect central biological processes that result in multiple negative health outcomes. ECHO Cohort researchers are working to extend this method to include several additional U.S. research sites, which will allow them to evaluate whether similar patterns are observed in a larger dataset. Larger studies will also help researchers characterize how demographic differences like income and sex may influence the development of multiple health outcomes during childhood.

Where can I learn more?

Find the full research article, titled “Subpopulations of children with multiple chronic health outcomes in relation to chemical exposures in the ECHO-PATHWAYS consortium,” in the journal Environment International.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published March, 2024

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Study Finds Link Between Phthalate Exposure During Pregnancy and Development of Multiple Health Outcomes in Children

ECHO Research Suggests Airborne Lead Exposure Affects Children’s Cognitive Development, Impacting Males More Than Females

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ECHO Research Suggests Airborne Lead Exposure Affects Children’s Cognitive Development, Impacting Males More Than Females

Authors: Amii Kress, Lisa Gatzke-Kopp, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Chemicals used in manufacturing, such as lead, are often released into the air and water. The government sets limits on the amount of pollution that is allowed based on what scientists believe are safe levels for humans. Studies suggest that there is no safe level of lead exposure for children. Despite a substantial decrease in children’s blood lead levels in recent decades, significant disparities in lead exposure still exist. Houses with old lead paint and areas with older and poorly kept housing or corroded pipes pose a higher risk of lead exposure. However, there is limited research on how airborne lead from industrial emissions affects children. This study tested whether lead pollution in the air, even at very low levels, is related to children’s intelligence and executive functioning.

What were the study results?

Children who lived in areas with relatively more lead pollution in the air in the early years of their lives exhibited less impulse control and had slightly lower IQ scores when they reached preschool and school age. Each increase in the level of airborne lead exposure was linked to an average decrease of 0.74 points in children’s IQ scores. The association between lead exposure and executive function was less straightforward in this study, with the influence changing noticeably only at higher levels. This was especially true for boys, who were more sensitive to the effects of airborne lead. Cognitive flexibility, or the ability to adapt to changing situations, and memory did not appear to be affected.

Note: Results reported here are for a single study. Other or future studies may provide new information or different results. You should always consult with a qualified healthcare provider for diagnosis and for answers to your personal questions.

What was this study's impact?

These results suggest that the amount of lead in the air during early childhood may affect children’s brain development. These findings could contribute to a broader approach to children’s health by considering all of the ways that a child’s environment could pose invisible risks. This study suggests that, in addition to efforts to reduce environmental pollution in general, attention to factors like nutrition that may mitigate the impact of exposure on children’s development could reduce health disparities of lead exposure for vulnerable individuals.

Who was involved?

This study looked at over 3,000 children from across the United States who were part of a research study that contributed to the ECHO Cohort.

What happened during the study?

Researchers used children’s home addresses to create a timeline of all the places that they lived from the time they were born until they were 5 years old. They then matched those locations to a database provided by the Environmental Protection Agency (EPA) that estimates the relative amount of lead pollution in the air for every half-square mile yearly. Researchers determined the average amount of exposure over the course of five years for each individual child and then examined whether the level of exposure was related to how the children performed on cognitive and IQ tests when they were between 3 and 8 years old.

What happens next?

Future studies are needed to examine whether other factors in the child’s environment make the effects of lead pollution better or worse. For instance, children with a healthy diet may be less likely to suffer from the effects of air pollution. Furthermore, previous work has suggested that males are more vulnerable to the effects of adverse conditions during neurodevelopment generally. These findings, along with evidence that lead exposure may affect male and female children differently, warrant additional research.

Where can I learn more?

Learn more about the additional data supporting this study through the EPA’s Toxic Release Inventory program. The program offers a Toxics Tracker website that people can use to learn more about the sources of air pollution in their communities.

Access the full journal article titled “Airborne Lead Exposure and Childhood Cognition: The Environmental Influence on Child Health Outcomes (ECHO) Cohort (2003-2022)” in the American Journal of Public Health.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published March, 2024

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ECHO Research Suggests Airborne Lead Exposure Affects Children’s Cognitive Development, Impacting Males More Than Females

ECHO Study Finds Link Between Phthalate Exposure and Preterm Birth, Estimates Potential Costs

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ECHO Study Finds Link Between Phthalate Exposure and Preterm Birth, Estimates Potential Costs

Authors: Leonardo Trasande, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of The Director, National Institutes of Health supported this research.

Why was this study needed?

Phthalates are widely used chemicals found in some consumer products, and previous research has linked phthalate exposure to preterm birth. In response, the use of di-2-ethylhexyl phthalate (DEHP), a common type of phthalate, has decreased in recent years. However, there is limited research on the effects of the replacement phthalates, and the costs associated with phthalate exposure remain unquantified. ECHO Cohort researchers wanted to learn about the potential connections between phthalates, their metabolites in the urine of pregnant individuals, and birth outcomes—including birth weight and length of pregnancy. The study also sought to estimate the potential costs associated with adverse birth outcomes.

What were the study results?

When the researchers grouped mothers based on the amount of DEHP metabolites (substances produced when the body breaks down DEHP) found in their urine, they found that the 10 percent with the highest levels had a 50 percent higher chance of giving birth before the 37th week of pregnancy compared to the 10 percent with the lowest levels.

Some common alternatives to DEHP were associated with even higher risk of preterm birth. Women exposed to the highest amounts of these alternative chemicals—phthalic acid, di-isodecyl phthalate (DIDP), di-n-octyl phthalate (DnOP), and diisononyl phthalate (DiNP)—had twice the risk of preterm birth compared to those with little to no exposure to these alternatives.

Researchers estimated that the number of premature births in the U.S. that could be linked to phthalate exposure in 2018 was between 24,000 and 120,000, potentially costing between $1.6 billion and $8.1 billion in medical expenses over the lifetime of the children.

Footnote: Results reported here are for a single study. Other or future studies may provide new information or different results. You should not make changes to your health without first consulting your healthcare professional.

What was this study's impact?

This ECHO Cohort research examines the effect of phthalates on birth outcomes such as preterm birth and birth weight. These findings associated adverse birth outcomes with exposure to DEHP and its chemically similar substitutes, which can inform the development of policies, programs, and practices that can help prevent or lessen potentially harmful exposures during pregnancy.

Who was involved?

The study included 5,006 mother-child pairs from 13 ECHO Cohort Study Sites across the U.S. Researchers included individuals with information on up to 20 urinary phthalate metabolites. The pregnant participants were aged 25 to 34 at the time they gave birth.

What happened during the study?

The researchers analyzed levels of 20 phthalate metabolites in urine samples collected at three points during each participant’s pregnancy. They also investigated the differences between specific types of phthalates, comparing DEHP with several newer alternatives developed to replace it. Then, the team looked for associations between these metabolite levels and preterm births. They also calculated the number of premature births that could be linked to phthalate exposure and the possible associated costs over the lifetime of the child.

What happens next?

Future research could look at how exposure to replacement phthalates affects child development after birth. The European Union has prohibited the use of certain phthalates in some consumer products—as have California and a few other U.S. states.

Where can I learn more?

Access the full journal article, titled “Prenatal phthalate exposure and adverse birth outcomes in the USA: a prospective analysis of births and estimates of attributable burden and costs,” in The Lancet Planetary Health.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published February, 2024

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ECHO Study Finds Link Between Phthalate Exposure and Preterm Birth, Estimates Potential Costs

ECHO Study Finds Flame-Retardant Chemicals May Increase Risk Of Preterm Birth and Higher Birth Weight

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ECHO Study Finds Flame-Retardant Chemicals May Increase Risk Of Preterm Birth and Higher Birth Weight

Authors: Deborah Bennett, Jiwon Oh, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Manufacturers commonly use flame-retardant chemicals known as organophosphate esters (OPEs) in products such as furniture, baby items, electronics, clothes, and building materials to prevent fires and make plastics more flexible. People can come into contact with OPEs in various ways, including swallowing or breathing indoor dust or absorbing it through the skin. Animal studies have revealed that OPEs can harm the growth and development of offspring. However, the connection between OPE exposure during pregnancy and birth outcomes has been unclear. ECHO researchers wanted to learn if there was a link between OPE levels in the urine of pregnant individuals and specific birth outcomes.

What were the study results?

Pregnant individuals exposed to specific classes of OPEs may face an increased risk of preterm birth, especially for baby girls and babies with higher birth weights. Three of these substances—diphenyl phosphate (DPHP), a combination of dibutyl phosphate and di-isobutyl phosphate (DBUP/DIBP), and bis(1,3-dichloro-2-propyl) phosphate—were associated with shorter pregnancies and higher risks of preterm birth only among female infants. Among male infants, higher concentrations of DPHP were associated with longer pregnancies.

Babies born to mothers with detectable levels of three other OPE markers—bis(1-chloro-2-propyl) phosphate, bis(2-methylphenyl) phosphate, and dipropyl phosphate—tended to have higher birth weights compared to those whose mothers had no detectable levels of these substances.

Note: Results reported here are for a single study. Other or future studies may provide new information or different results. You should not make changes to your health without first consulting your healthcare professional.

What was this study's impact?

In the past decade, OPEs have been increasingly used as flame retardants after polybrominated diphenyl ether (PBDE) flame retardants were phased out due to health risks. ECHO research examines the potential impact of these now more widespread OPE chemicals on pregnancy outcomes such as preterm birth and birth weight. The findings can inform policies, programs, and practices to help decrease exposure.

Who was involved?

The study included 6,646 pregnant participants at 16 ECHO Cohort Study Sites across the U.S. and Puerto Rico.

What happened during the study?

Researchers measured a total of nine OPE markers in urine samples collected from 6,646 pregnant participants across 16 ECHO Cohort Study Sites—often during their third or second trimesters. The researchers then assessed birth outcomes, including the length of pregnancy and birth weight, using medical records or parent reports.

What happens next?

OPEs tend to stay in the human body for short periods, usually hours to days. To better understand how these chemicals might affect birth outcomes, researchers can use multiple measurements of urinary OPE biomarkers. This could help identify when the body might be more sensitive to these chemicals. Additionally, learning more about how people are exposed to these chemicals can help identify ways to reduce exposure, especially during pregnancy.

Where can I learn more?

Access the full journal article, titled “Associations of Organophosphate Ester Flame Retardant Exposures during Pregnancy with Gestational Duration and Fetal Growth: The Environmental influences on Child Health Outcomes (ECHO) Program,” in Environmental Health Perspectives.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published January 24, 2024

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ECHO Study Finds Flame-Retardant Chemicals May Increase Risk Of Preterm Birth and Higher Birth Weight