The Chalkboard: Recent EPA Children’s Health Research Updates
March/April 2025
Exploring PFAS Exposures, Toxicity
Per- and polyfluoroalkyl substances (PFAS) have been found to be ubiquitous in the environment and in samples of tissue from both wildlife and humans. Commonly referred to as “forever chemicals” because they do not break down, some PFAS have also been linked to a host of adverse health effects in children, including development delays, low birth weight, accelerated puberty, and behavioral changes.
Drinking water and food are known to be primary routes of exposure to PFAS chemicals, but few studies exist on how household dust might contribute, a potentially important consideration for protecting children’s health due to their hand-to-mouth behavior and increased vulnerabilities from their relatively small and still-developing bodies.
In a unique research project aimed at shedding light on the potential connection between PFAS exposure and household dust, a team of EPA scientists leveraged data from the National Children’s Study (NCS). They analyzed frozen, archived biological material and house dust samples to search for evidence of links between home levels of PFAS and how much was found in the biological samples (PFAS body burden) of those living there. Findings revealed a positive association between the two.
In another study, a team of EPA researchers conducted laboratory-based exposure experiments to track how exposures to two types of long-chain PFAS (PFO4DA and PFO5DoA) effect maternal and fetal health. The study was designed to increase what is known about the toxicity of these two and similar compounds, which have been detected in biomonitoring studies near manufacturing sites in the U.S. and China.
While further research is needed, results might prove to be an early warning signal for children’s health. Both compounds produced adverse health impacts and acute toxicity from short-term exposures to laboratory animals, “indicating need for additional toxicity data to evaluate potential human health risks,” the research team concluded.
Sources:
Wallis, D. J., Miller, K. E., DeLuca, N. M., Thomas, K., Fuller, C., McCord, J., ... & Minucci, J. M. (2024). Understanding prenatal household exposures to per-and polyfluorylalkyl substances using paired Biological and dust measurements with sociodemographic and housing variables. Environment International, 194, 109157. See a summary and a link in the EPA Science Inventory.
Conley, J. M., Lambright, C. S., Evans, N., Bangma, J., Ford, J., Hill, D., & Gray Jr, L. E. (2024). Long-chain perfluoroalkylether carboxylic acids PFO5DoA and PFO4DA alter glucose, bile acid, and thyroid hormone homeostasis in fetal rats from 5-day maternal oral exposure. Environmental Research, 263, 120210.
Investigating Potential Long-term Impact of Gestational Exposures
When it comes to children’s environmental health, timing can mean everything. Exposures to chemicals that might not harm adults can have dramatic, long-lasting adverse health impacts to children if they occur during particularly vulnerable stages of early life. This is particularly true when it comes to brain and other neurodevelopment.
Results from three recent studies, one by grantees support by an EPA Science to Achieve Results (STAR) grant, and the other two by teams of EPA staff researchers and their partners, shed light on this important aspect of children’s health.
1. Organophosphate Ester Exposure and Executive Function
In the first, a team of EPA grantees used data from the Health Outcomes of Measurements of the Environment (HOME) Study to investigate how gestational exposure to organophosphate esters (OPEs), chemicals used as flame retardants and plasticizers in many consumer products, might impact childhood development and executive function years later. Using statistical analysis of HOME data— measurements of gestational OPE urinary metabolites at different stages of pregnancy and at time of delivery, and executive function assessments performed at age 12—the team found limited evidence of a relationship between OPE exposure at birth and executive function during adolescence.
This novel research provides important clues into the potential for OPEs to impact children’s health, and points to the need for further research. “Given the scarcity of epidemiological studies that have focused on executive function as an endpoint for OPE neurotoxicity, future studies can help investigate this research question further, particularly among large birth cohorts with multiple measurements of OPE metabolite concentrations during pregnancy,” state the researchers in the paper presenting their results.
2. Iodine Deficit and Perchlorate
In another study, EPA researchers and their partners tested how a diet deficient in iodine, which plays a critical role in thyroid function and brain development, might lead to increased vulnerability to exposures to perchlorate, a chemical oxidizer used in such things as rocket fuel, fireworks, airbags, and safety flares.
They found that the combination of both iodine deficiency and perchlorate exposure to pregnant rats was associated with transcriptional alterations to the thyroid glands and brains of their offspring. The offspring were found to have structural changes in their brains, and persistent neurobehavioral impairments as adults. “We report an exacerbation of the effects of developmental exposure to perchlorate on the brain by concomitant dietary iodine deficiency,” the authors of the study note.
3. Comparing Biomarkers of Prenatal Methylmercury Exposure
In a third recent study, EPA researchers conducted an extensive review of the scientific literature to compare the biomarkers and determine which would be most apt for assessing effects of exposure to the developmental neurotoxin methylmercury (MeHg) during pregnancy.
By analyzing five papers containing both maternal hair and cord blood data, a team of EPA scientists found that cord blood was often a more sensitive biomarker than maternal hair. Data on maternal blood suggested that it may be the most sensitive of the three; however, data was limited, and further research would be needed to form a conclusion about maternal blood.
The data derived from the literature review could be used to inform future studies on the relationship between maternal MeHg and developmental neurotoxicity (DNT) in children.
Sources:
Vuong, A. M., Percy, Z., Yang, W., Godbole, A. M., Ospina, M., Calafat, A. M., . . . & Chen, A. (2024). Gestational organophosphate esters (OPEs) and executive function in adolescence: The HOME Study. Environmental Research, 263, 120239.
Gilbert, M. E., Hawks, M. G., Bell, K. S., Oshiro, W., Wood, C., George, B. J., ... & Ford, J. (2024). Iodine Deficiency Exacerbates Thyroidal and Neurological Effects of Developmental Perchlorate Exposure in the Neonatal and Adult Rat. Toxics, 12(12), 842.
Kopylev, L., Dzierlenga, M., Lin, Y. S., Nachman, R., Radke, E., Ru, H., & Segal, D. (2024). Which prenatal biomarker is most appropriate for methylmercury dose-response for neurodevelopmental effects? Journal of Toxicology and Environmental Health, Part B, 1–10.
Particulate Matter and Infant Mortality
A robust body of research concludes that long-term exposure to the tiniest bits of air pollution, microscopic particulate matter with a diameter of 2.5 micrometers or less (PM2.5), can significantly increase the risk of adult mortality. Less, however, is known about how PM2.5 exposures impacts the risk of infant mortality. Reducing infant mortality is a primary focus across EPA’s efforts to improve children’s environmental health.
Recently, a team of researchers from the University of Washington’s School of Public Health and EPA published results of a study analyzing the association between increased long-term PM2.5 exposure and infant mortality. The team conducted a case-control study using publicly-available data to create a birth cohort of all infants born in North Carolina between 2003 and 2015—more than 1.3 million births. Mean PM2.5 exposure decreased substantially as air quality improved over the study period.
Analysis pointed to a possible association between infant mortality and PM2.5 exposure, with stronger effects at the higher PM2.5 concentrations for the earlier years of the study, and lower effects in later years with improved air quality. Researchers point out the need for further investigations given the relatively few studies on PM2.5 and infant mortality. They conclude their findings will be important to inform decisions that aim to protect infants’ environmental health with respect to air pollution.
Source: Jampel, S. M., Kaufman, J., Enquobahrie, D. A., Wilkie, A. A., Gassett, A. J., & Luben, T. J. (2024). Association between fine particulate matter (PM2. 5) and infant mortality in a North Carolina birth cohort (2003–2015). Environmental Epidemiology, 8(6), e350.
See a summary and link to the published research paper in EPA’s Science Inventory.