US Preschoolers Exposed to Dozens of Potentially Harmful Chemicals

American toddlers are regularly exposed to a vast mix of potentially harmful industrial and consumer chemicals, a new study has cautioned.

Researchers from the National Institutes of Health’s Environmental influences on Child Health Outcomes (ECHO) program, led by the University of California, Davis conducted one of the most extensive investigations to date into the chemical exposure among young children.

The study focused on a group of 201 children aged between two and four from four states: California, Georgia, New York and Washington.

They tested for 111 different chemicals and detected 96 in at least five children, uncovering widespread contact with substances commonly found in plastics, personal care products, household dust and air pollution.

Exposure to environmental chemicals—including pesticides, flame retardants, plasticizers, parabens, bisphenols and combustion byproducts—has been previously linked to developmental delays, endocrine disruption and rising health issues.

Children encounter environmental chemicals through daily activities like eating, drinking, breathing air, and touching surfaces.

Deborah H. Bennett, lead author and UC Davis public health professor, emphasized the urgency: “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.”

The study found younger children—particularly two-year-olds—often carried higher levels of these chemicals than their older peers.

They also found the children had higher levels of several chemicals than their mothers did during pregnancy. These included two phthalates, bisphenol S and the pesticide biomarkers 3-PBA and trans-DCCA.

Minority children also showed elevated concentrations of specific substances such as parabens, phthalates and polycyclic aromatic hydrocarbons (PAHs)—highlighting persistent disparities in environmental health.

Alarmingly, nine compounds identified in toddlers were absent from the National Health and Nutrition Examination Survey (NHANES), suggesting significant gaps in national chemical monitoring programs.

Jiwon Oh, first author and postdoctoral scholar at UC Davis, underlined the need for policy reform: “This new study highlights the urgent need for expanded biomonitoring and stronger regulations to protect children from harmful exposures.”

Recommendations for parents and caregivers include washing hands frequently, especially before eating, ventilating living spaces and avoiding plastics marked #3, #6 and #7 as they may contain BPA or similar chemicals.

Using phthalates and phthalate alternatives used in plastics like toys and food packaging can also reduce exposure. Avoiding parabens commonly used in cosmetics, lotions, shampoos and pharmaceuticals is also advised.

The researchers propose long-term biomonitoring across more diverse populations and the inclusion of emerging chemicals in national surveillance.

They also call for stricter regulation of chemical use in consumer products and building materials. Early, proactive approaches are crucial for shielding children from invisible environmental threats.

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Reference

Oh, J., Buckley, J. P., Kannan, K., Pellizzari, E., Miller, R. L., Bastain, T. M., Dunlop, A. L., Douglas, C., Gilliland, F. D., Herbstman, J. B., Karr, C., Porucznik, C. A., Hertz-Picciotto, I., Morello-Frosch, R., Sathyanarayana, S., Schmidt, R. J., Woodruff, T. J., & Bennett, D. H. (2025). 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. Environmental Science & Technology. https://doi.org/10.1021/acs.est.4c13605