96 Chemicals Found in U.S. Preschoolers' Bodies, 9 Not Even Tracked by the CDC
Researchers at UC Davis tested the blood and urine of 201 preschoolers from four U.S. states and found 96 distinct chemicals circulating in their bodies. The chemicals span multiple classes: pesticides, plasticizers, flame retardants, parabens, and bisphenols. Thirty-four of those chemicals showed up in more than 90% of the children tested. Nine of them are not even tracked by the CDC's main chemical surveillance program.
The findings, published in Environmental Science & Technology in July 2025, represent one of the most thorough biomonitoring studies of young children ever conducted in the United States.
Why Early Childhood Exposure Matters
Children aged 2 to 4 are not small adults. Pound for pound, they eat more food, drink more water, and breathe more air than adults. They crawl on floors, put objects in their mouths, and absorb chemicals more readily through their skin and digestive systems.
This is also the period when the brain is undergoing rapid development. Neural connections are forming at a pace that will never be matched later in life. Exposure to endocrine-disrupting chemicals, neurotoxic pesticides, and plasticizers during this window can interfere with hormone signaling, cognitive development, and immune function.
"Childhood exposure to potentially harmful chemicals is widespread," the researchers stated. "This is alarming because early childhood is a critical window for brain and body development."
The study also found that younger children within the 2-to-4 age range had higher chemical concentrations than older toddlers, suggesting that exposure intensity peaks at the youngest ages, precisely when vulnerability is greatest.
What the Study Found
The UC Davis team recruited 201 children ages 2 through 4 from families in California, Georgia, New York, and Washington. They collected blood and urine samples and screened them for a broad panel of chemical compounds.
Here is what the data showed:
- 96 chemicals were detected in at least five children across the study.
- 48 chemicals were found in more than half of the children tested.
- 34 chemicals appeared in over 90% of all participants.
- 9 chemicals detected in the children are not currently monitored by the CDC's National Health and Nutrition Examination Survey (NHANES), the federal government's primary tool for tracking chemical exposure in the U.S. population.
The chemical classes detected included phthalates (found in flexible plastics and personal care products), parabens (used as preservatives in cosmetics and food packaging), bisphenols (present in can linings and receipt paper), benzophenones (UV filters in sunscreens and plastics), and multiple pesticide metabolites linked to agricultural and residential pest control.
Children in the study had higher levels of several chemicals than their own mothers had shown during pregnancy, according to ScienceDaily's coverage of the research. This suggests that postnatal exposure through food, household products, and indoor environments adds substantially to the chemical burden children carry from the womb.
Nine Chemicals the Government Is Not Watching
Nine of the chemicals detected in these preschoolers fall completely outside the scope of NHANES. This means the federal government has no systematic data on how many Americans are exposed to these compounds, at what levels, or whether those levels are changing over time.
NHANES has been the gold standard for population-level chemical exposure data since the 1970s. Public health agencies, regulators, and researchers rely on it to identify emerging threats and track whether interventions are working. When chemicals show up in children's bodies but not in the national monitoring program, it creates a blind spot that delays regulatory action.
The study did not name all nine chemicals individually in the public summaries, but the researchers emphasized that this gap highlights the need to expand federal biomonitoring to keep pace with the thousands of synthetic chemicals now in commercial use.
Racial and Ethnic Disparities
The study documented significant disparities in chemical exposure across racial and ethnic groups. Children from racial and ethnic minority backgrounds had higher levels of parabens, certain phthalates, and polycyclic aromatic hydrocarbons (PAHs) compared to white children.
These differences likely reflect inequalities in housing conditions, proximity to pollution sources, access to safer consumer products, and dietary patterns shaped by food availability in different neighborhoods. PAHs, for instance, are produced by vehicle exhaust, industrial emissions, and cooking with certain fuels. Communities near highways or industrial zones bear disproportionate exposure.
This fits a well-documented pattern: chemical exposure in the United States is not distributed equally. Lower-income communities and communities of color consistently face higher environmental health burdens, a pattern that starts before birth and, as this study shows, continues through early childhood.
Trends Over Time: Some Chemicals Declining, Others Rising
The study included longitudinal data spanning 2010 to 2021, offering a rare look at how children's chemical exposure has changed over the past decade.
Some chemicals showed encouraging declines. Triclosan (an antibacterial agent banned from hand soaps in 2016), parabens, PAHs, and most phthalates all decreased over the study period. These reductions likely reflect regulatory actions and voluntary industry reformulations in response to public pressure.
But the news was not all good. DINCH, a plasticizer marketed as a "safer" replacement for certain phthalates, showed upward trends. So did metabolites of emerging pesticides. This pattern of "regrettable substitution," where banned chemicals are replaced by newer compounds with limited safety data, is a recurring problem in chemical regulation.
The fact that replacement chemicals are showing up at increasing levels in preschoolers' bodies before their long-term safety has been established raises questions about whether the current approach to chemical regulation adequately protects children.
Where These Chemicals Come From
For parents trying to make sense of 96 chemicals across dozens of classes, it helps to understand the primary exposure pathways.
Food is one of the largest sources. Pesticide residues on fruits, vegetables, and grains enter children's diets directly. Phthalates and bisphenols can leach from food packaging, plastic containers, and processing equipment. Studies have repeatedly shown that highly processed foods contain higher levels of plasticizers than whole foods prepared at home.
Household products are another major pathway. Flame retardants in furniture, carpeting, and electronics settle into house dust. Children who play on floors and put their hands in their mouths ingest this dust regularly. Personal care products (shampoos, lotions, soaps) are direct sources of parabens and certain phthalates.
Indoor air carries volatile compounds from cleaning products, air fresheners, and building materials. Young children spend most of their time indoors, which amplifies this exposure route.
Water can carry pesticide runoff, PFAS, and other contaminants depending on the source and treatment methods.
No single product or food is responsible. The 96-chemical finding reflects the cumulative effect of daily contact with synthetic compounds from dozens of sources at once.
What This Means for Parents
Reducing chemical exposure to zero is not realistic. These compounds are woven into everyday products and food systems. But research consistently shows that targeted changes can meaningfully lower the chemical levels in children's bodies within days.
Choose whole foods over processed foods when possible. Processing and packaging introduce plasticizers and other chemicals that whole fruits, vegetables, grains, and proteins do not carry.
Wash produce thoroughly. Rinsing fruits and vegetables under running water removes a significant portion of surface pesticide residues. For items on the Environmental Working Group's "Dirty Dozen" list, consider organic options.
Minimize plastic food contact. Store food in glass or stainless steel containers. Never microwave food in plastic, which accelerates chemical leaching. Avoid plastic wrap in direct contact with food.
Reduce household dust. Wet-mop floors regularly. Vacuum with a HEPA filter. Dust contains flame retardants and other chemicals that young children ingest through hand-to-mouth behavior.
Check product labels. Tools like VeriFoods allow parents to scan product barcodes and check whether foods have been independently tested for contaminants including pesticides, heavy metals, and other chemical residues. Understanding what is in your child's food is a practical first step toward reducing dietary exposure.
Advocate for better monitoring. The fact that nine chemicals found in preschoolers are not tracked by NHANES means the system designed to protect public health has gaps. Supporting expanded biomonitoring and stricter pre-market safety testing for new chemicals is part of the long-term solution.
Sources
UC Davis Health News - "New study: U.S. preschoolers exposed to broad range of potentially harmful chemicals" - July 2025. https://health.ucdavis.edu/news/headlines/new-study-us-preschoolers-exposed-to-broad-range-of-potentially-harmful-chemicals/2025/07
ScienceDaily - "Researchers tested 200 toddlers — 96 chemicals were lurking in their bodies" - July 1, 2025. https://www.sciencedaily.com/releases/2025/07/250701234739.htm