(SACRAMENTO, Calif.) — A national study published in Environmental Science & Technology finds children aged 2 to 4 years in the United States are routinely exposed to a broad range of potentially harmful chemicals. Many of the chemicals the researchers identified are not routinely monitored and may pose health risks.
The research was conducted by multiple institutions across the United States in coordination with the Environmental influences on Child Health Outcomes ( ECHO ), a program supported by the National Institutes of Health ( NIH ).
The researchers analyzed urine samples from 201 children aged 2 to 4 years. They tested for 111 chemicals. Their study found:
“Our study shows that childhood exposure to potentially harmful chemicals is widespread. This is alarming because we know early childhood is a critical window for brain and body development,” said Deborah H. Bennett , lead author and UC Davis professor in the Department of Public Health Sciences . “Many of these chemicals are known or suspected to interfere with hormones, brain development and immune function.”
Children exposed to chemicals through everyday activities
The NIH-funded ECHO Cohort combines data from pregnancy and pediatric cohorts to examine the impacts of early environmental exposures on child health and development. This study looked at samples of 201 children from four states (California, Georgia, New York and Washington).
The researchers looked for childhood exposure to common environmental chemicals, including:
Children are exposed to these environmental chemicals through everyday activities, such as eating, drinking, breathing indoor and outdoor air and touching contaminated surfaces.
Frequent hand-to-mouth contact, playing close to the ground, and higher intake rates relative to their smaller body weight make kids especially vulnerable to chemical exposure.
Trends and disparities
In addition to the widespread exposure, the researchers noted some trends.
Most of the children’s mothers had provided urine samples during pregnancy. This allowed the researchers to analyze the chemicals in the mother’s urine with the chemicals in the children’s urine.
They found the children had higher levels of several chemicals than their mothers did during pregnancy. These included two phthalates, bisphenol S (often used as a BPA replacement) and the pesticide biomarkers 3-PBA and trans-DCCA.
Need for more monitoring and regulation
The researchers emphasize that further studies are necessary to comprehend the long-term health implications of these chemicals.
“Exposure to certain chemicals in early childhood — such as pesticides, plasticizers and flame retardants — has been linked to developmental delays, hormone disruption and other long-term health issues,” said Jiwon Oh , first author of the study and a postdoctoral scholar in the UC Davis Department of Public Health Sciences. “This new study highlights the urgent need for expanded biomonitoring and stronger regulations to protect children from harmful exposures.”
A complete list of authors and funders appears in the paper.
How to limit chemical exposure
It is impossible to eliminate all chemical exposures. Yet, there are many simple steps parents can take to help reduce their children’s contact with harmful chemicals.
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Exposures to Contemporary and Emerging Chemicals among Children Aged 2 to 4 Years in the United States Environmental Influences on the Child Health Outcome (ECHO) Cohort Click to copy a
30-Jun-2025
The authors declare the following competing financial interest(s): RJS consults for Beasley Law, Inc. RJS has received travel support to present at the 35th Annual Meeting of the Organization of Teratology Information Specialists (OTIS). RJS and DHB consult for Linus Biotechnology, Inc. The remaining authors have no conflicts of interest to report.