The team, led by co-corresponding authors Dong Keon Yon of Kyung Hee University College of Medicine and Jiseung Kang, classified children as prenatally exposed if their mothers received two or more opioid prescriptions during pregnancy. That threshold was chosen to distinguish sustained exposure from a single, isolated dispensing event. The exposed children were compared in two ways: against unexposed children from the general population, and, in a more stringent test, against their own unexposed siblings, a design that partially controls for the family environment and shared genetics.

The headline result was striking. Compared with unexposed children, those with prenatal opioid exposure had a 28 percent higher rate of hospital admission, with an adjusted incidence rate ratio of 1.28 and a 95 percent confidence interval of 1.28 to 1.29. When the comparison was restricted to siblings within the same family, the association shrank to an adjusted rate ratio of 1.08, with a confidence interval of 1.07 to 1.10, but it did not disappear. That pattern, the authors argue, is consistent with a genuine contribution of the drug itself alongside a substantial contribution from factors shared within households.

The study also uncovered a clear dose-response relationship, one of the criteria epidemiologists look for when weighing whether an association is causal. Children whose mothers received low doses of opioids showed an adjusted rate ratio of 1.19, while those whose mothers received high doses showed a ratio of 1.40. In other words, the more opioid exposure a fetus experienced, the greater the subsequent risk of hospital admission in childhood. The elevated rates spanned multiple categories of illness, including infections as well as respiratory, gastrointestinal, and genitourinary conditions, a breadth that points toward possible effects on the developing immune system rather than damage confined to a single organ system.

Perhaps the most consequential finding was temporal. The association between prenatal opioid exposure and hospital admission was strongest in the earliest years of life and was most pronounced up to age five. Joint first author Yesol Yim described the fading of the signal as the study’s biggest surprise. The excess risk was clearest in the first year of life and had largely disappeared after age five, a pattern she interpreted as evidence of a window of vulnerability in early infancy rather than a lifelong effect, and one in which pediatric follow-up can make a real difference. For clinicians, that time-limited risk profile transforms an abstract statistical association into an actionable surveillance strategy.

The biological rationale for such a link is plausible, though not yet proven. Prenatal opioid exposure has been associated in prior research with disruptions to infant development and to immune system function, mechanisms that could plausibly increase susceptibility to the infections and respiratory illnesses that dominated the admission data. Opioid prescriptions and doses have risen considerably in clinical practice over recent decades, and the scale of prenatal exposure is far from trivial. In the United States, data have shown that between 14 and 22 percent of women filled an opioid prescription during pregnancy, making even a modest relative increase in childhood hospitalizations a meaningful public health concern.

What sets the South Korean study apart is the unusual cleanliness of its exposure data. As co-corresponding author Jiseung Kang explained, opioids in South Korea are obtained almost entirely by prescription, so the researchers could examine prescribed opioid exposure in pregnancy with unusual precision. Following nearly three million children for up to fourteen years gave the team the statistical power to examine dose, timing, and specific causes of admission separately, and Kang argued that the consistency of the pattern across all of these analyses is what makes the finding difficult to dismiss. Prior studies in this field have been hampered by confounding factors, limited sample sizes, or restricted follow-up durations, shortcomings this cohort was designed to overcome.

The authors themselves urge caution, and their caveats deserve as much attention as the headline numbers. The study relied on electronic health records, which record prescriptions written and dispensed but may not reflect the medication a patient actually took. Unmeasured factors shared within families, such as parental health behaviors, socioeconomic stressors, or genetic predispositions, may still partly explain the observed associations, and the narrowing of the effect in the sibling comparison is direct evidence of how much such factors matter. The sibling analysis, while powerful, cannot eliminate influences that vary between siblings born at different times or under different circumstances.

The research team was careful to frame its findings as a call for better care rather than a prohibition. Joint first author Hyeon Jin Kim emphasized that the message is not that pregnant women should never receive opioids, since for some patients pain relief is essential. Instead, the recommendation is that opioids in pregnancy be prescribed at the lowest effective dose for the shortest possible time, and that children born after such exposure may benefit from closer routine health checks, particularly during infancy when the risk was found to be highest. Co-corresponding author Dong Keon Yon echoed that framing, noting that the dose-dependence points to a possible biological effect while acknowledging that shared family factors clearly explain part of what the study observed.

The study, an observational analysis of nationwide health insurance data rather than a randomized trial, was funded by South Korea’s Ministry of Science and ICT, Ministry of Health and Welfare, National Research Foundation, and Ministry of Education, none of which had a role in the study design, data collection, analysis, or manuscript preparation. The authors declared no competing interests. For families and clinicians, the practical takeaway is measured: prenatal opioid exposure, as captured by two or more maternal prescriptions, is associated with a modestly elevated, dose-dependent, and age-limited risk of childhood hospital admission, concentrated in infancy and driven largely by infections and respiratory illness. That risk, while real, is neither uniform nor permanent, and it appears most amenable to mitigation through vigilant postnatal monitoring in the first years of life, when the window of vulnerability is open and pediatric care can respond.

Subject of Research: The association between prenatal opioid prescription exposure and childhood hospital admission rates in a nationwide South Korean birth cohort.

Article Title: Opioid prescriptions during pregnancy linked to higher rates of childhood hospital admission

Article References: Opioid prescriptions during pregnancy linked to higher rates of childhood hospital admission. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: opioids, pregnancy, prenatal exposure, hospital admission, pediatrics, PLOS Medicine, South Korea, birth cohort, epidemiology, childhood infections, dose-response, electronic health records

The review, led by researchers who have spent years working with pregnant baboons, surveys the milestones of prenatal brain maturation in nonhuman primates and catalogs how environmental insults—air pollution, ionizing radiation, toxic metals, pesticides, viral and bacterial infections, excess heat, and drugs of abuse—can derail them. The stakes are considerable. The fetal brain undergoes its most dramatic expansion during gestation, laying down the cortical layers, cerebellar circuits, and vascular networks that will support cognition and behavior for a lifetime. Disruptions during this window can produce long-term cognitive, emotional, and behavioral deficits, and identifying the moments of greatest sensitivity is central to prevention.

What makes the baboon so valuable is a matter of timing and anatomy. Rodents are altricial animals: their brains at birth correspond roughly to a human fetus in the third trimester, so many developmental processes that occur before birth in people happen after birth in mice and rats. In baboons and humans, by contrast, key steps of cerebellar development unfold during gestation itself. The external granule cell layer of the cerebellum, a proliferative zone that produces the granule neurons governing motor control and motor learning, can be tracked in fetal baboon tissue using molecular markers such as Pax6, which labels progenitor cells; Ki67, which marks dividing cells; and Tag1, which flags neurons that have begun to differentiate. Quantifying these cell populations offers a direct readout of whether an environmental insult has disturbed cerebellar development—a process that in rodents would be largely postnatal and therefore harder to align with human pregnancy.

The parallels extend across the entire brain. Baboons share roughly 92 percent of their genomic sequence with humans, and like us they possess a gyrencephalic cortex, folded into gyri and sulci rather than smooth. Imaging studies show that baboon brain volume and cortical surface area are highly heritable, that the corpus callosum follows a developmental trajectory closely mirroring the human one, and that grey-to-white matter ratios, myelination, and cortical laminar development share strong temporal and structural similarities with our own species. Even the cerebellum’s molecular layer thickens in late gestation and early infancy in both baboons and humans, reflecting comparable maturation of Purkinje cells.

The vascular system tells a similar story. By gestational day 120, corresponding to the end of the human second trimester, the four major cerebral arteries—anterior, middle, posterior, and basilar—are already distinguishable in the baboon fetus. By day 165, the third-trimester equivalent, fetal cerebral arteries can constrict in response to elevated intraluminal pressure, demonstrating myogenic tone, and they respond robustly to depolarizing stimuli such as potassium chloride, showing that smooth muscle contractility is being established in utero. The neurovascular unit—neurons, astrocytes, and endothelial cells—is remarkably conserved across primates, and primate brains arrive at birth with more advanced vascular networks than rodents, supporting the prolonged cortical development, including postnatal neurogenesis and gyrification, that characterizes our species.

Against this backdrop, the review assembles the evidence on environmental threats. Heavy metals cross the placental barrier with ease: arsenic is associated with miscarriage, stillbirth, and intrauterine growth restriction through oxidative stress and endocrine disruption; cadmium with preterm birth and small-for-gestational-age infants, possibly by interfering with placental nutrient transport; lead with low birth weight and impaired neurodevelopment; and methylmercury, accumulated from contaminated seafood, with lasting cognitive and motor deficits. Notably, a study of pregnant baboons measured forty elements across maternal and fetal blood, hair, nails, placenta, amniotic fluid, and fetal tissues, and found that element concentrations closely mirrored those of late-stage human pregnancies—reinforcing the baboon’s value for studying both normal maternal-fetal physiology and toxicology.

Physical and biological insults leave their own signatures. Excessive doses of ionizing radiation, above 0.1 gray, can cause miscarriage, growth restriction, malformations, and reduced cognitive function, with sensitivity depending on gestational stage; baboon studies have identified biomarkers such as aspartate aminotransferase, LDH, Flt3-ligand, and the neutrophil-to-lymphocyte ratio that distinguish total-body from partial-body irradiation and could guide treatment after accidental exposure. Maternal hyperthermia in pregnant baboons—body temperature of 41 to 42 degrees Celsius without fever—produced fetal blood pressure drops, elevated heart rate, severe acidosis, hypoxia, and hypercapnia, and doubled uterine contractility, raising the risk of preterm birth. Viral infections tell perhaps the starkest story: in baboons, herpesvirus papio 2 and cytomegalovirus cause placentitis with seroprevalence reaching 95 percent, and perinatal Zika virus infection produces significant fetal cerebral cortical injury that can end in fetal death.

Alcohol receives particularly detailed attention, and the baboon data are sobering. Three episodes of maternal alcohol exposure during the second-trimester equivalent, producing maternal blood alcohol levels around 80 milligrams per deciliter—the legal driving limit in most of the United States—caused fetal growth restriction, with amniotic fluid levels reaching 63 milligrams per deciliter, near the threshold of noticeable behavioral impairment in humans. Near term, exposed offspring showed reduced abdominal and head circumferences. A single binge episode, modeled with a gastro-nasal catheter delivering 3 grams of ethanol per kilogram to approximate a blood alcohol concentration of 0.2 percent—the equivalent of six to eight drinks in two hours—increased placental permeability and fetal brain perfusion, paradoxically making the fetal brain more vulnerable to toxic insult. Moderate doses during the second trimester dilated the middle cerebral artery, an effect reversed by blocking cannabinoid CB1 and CB2 receptors, and proteomic profiling revealed lasting alterations in mitochondrial and cytoskeletal proteins of cerebral arteries exposed earlier in gestation.

Cannabinoids and tobacco complete the picture. Roughly 5 percent of pregnant women self-medicate with marijuana, and chronic prenatal THC exposure in rhesus macaques altered fetal brain growth on MRI, with cerebrospinal fluid microRNAs pointing to disrupted axonal guidance and netrin signaling. Quantitative PCR in fetal baboon cerebellum confirms that both cannabinoid receptor genes, Cnr1 and Cnr2, are expressed at gestational day 120, the end of the second-trimester equivalent—meaning the fetal endocannabinoid system, which regulates synaptogenesis and circuit maturation, is present and potentially disruptable exactly when THC arrives. Epigenetic changes after prenatal cannabinoid exposure may even persist across generations, and are linked to psychiatric conditions including autism spectrum disorder, ADHD, and schizophrenia. Perinatal exposure to environmental tobacco smoke in rhesus monkeys selectively upregulated nicotinic acetylcholine receptors in the brainstem and cortex, a hallmark of nicotine neuroteratogenesis, while prenatal alcohol exposure in macaques and vervet monkeys reduced hippocampal and cortical neuron numbers and disrupted miRNA regulation of genes critical for synaptic development, including a previously unknown link to the EFNB1 gene.

The authors acknowledge that nonhuman primate research carries significant ethical and logistical burdens—long lifespans, complex care, strict welfare requirements—but they argue the translational payoff justifies the investment. Rodent preclinical results frequently fail in human clinical trials, a gap that may stem from precisely the developmental and vascular differences the baboon model is positioned to resolve. Computational models already predict that primates, including humans, are more sensitive to ethanol’s inhibition of neocortical neuronal proliferation than rodents, with significant neuronal deficits at blood alcohol concentrations equivalent to a single standard drink within an hour. As cannabis legalization reshapes perceptions of safety, as air pollution and heat extremes intensify, and as viral threats continue to emerge, the baboon offers a rare window into the mechanisms by which the prenatal environment writes itself into the developing brain—and a foundation for the prevention and treatment strategies that neurodevelopmental medicine urgently needs.

Subject of Research: Prenatal environmental exposures and fetal brain development studied with baboon and other nonhuman primate models

Article Title: Prenatal environmental exposures and brain development: studies with baboons and other nonhuman primates

Article References: Iskusnykh, I. Y., Thapa, S., Chizhikov, V. V., & Bukiya, A. N. (2025). Prenatal environmental exposures and brain development: studies with baboons and other nonhuman primates. Advances in Drug and Alcohol Research, 5, Article 14858. https://doi.org/10.3389/adar.2025.14858

Image Credits: AI Generated

DOI: 10.3389/adar.2025.14858

Keywords: neuroscience, developmental biology, toxicology, baboon model, fetal brain, prenatal exposure, FASD, cannabinoids, Prenatal, environmental, exposures, brain

Rare earth elements are a group of seventeen chemically similar metals, including neodymium, cerium, and ytterbium, that have become indispensable to modern technology. They appear in magnets, batteries, catalysts, and electronic displays, and as mining and manufacturing have intensified worldwide, these elements have quietly accumulated in soil, water, and air. People are exposed through food, drinking water, and dust, and pregnant women pass them across the placenta to their developing babies. While previous research had hinted that prenatal exposure to these metals could impair childhood neurodevelopment, the biological mechanisms remained murky.

To probe those mechanisms, researchers turned to the Wuhan Healthy Baby Cohort, a long-running birth cohort study in central China. The team, led by Ya Xie and Wei Xia of Wuhan Children’s Hospital and Huazhong University of Science and Technology, measured concentrations of thirteen rare earth elements in urine samples collected from mothers during the first trimester of pregnancy. They then performed metabolomic profiling on cord blood, the blood remaining in the placenta after birth, capturing a snapshot of each newborn’s metabolic state. Two years later, trained assessors evaluated each child’s cognitive and motor skills using the Bayley Scales of Infant Development, a widely used standardized test.

The results were striking. After adjusting for a range of covariates, the researchers found that higher first-trimester maternal levels of seven rare earth elements were each significantly associated with increased odds of cognitive developmental delay. The elements neodymium, samarium, gadolinium, holmium, erbium, thulium, and ytterbium each carried elevated risk, with adjusted odds ratios ranging from 1.13 to 1.25 for every one-unit increase in natural log-transformed urinary concentration. In practical terms, a modest rise in maternal exposure translated into a measurable increase in the likelihood that a toddler would score below developmental benchmarks on cognitive testing.

Because people are exposed to mixtures of rare earth elements rather than single metals in isolation, the team also used two statistical approaches designed for environmental mixtures: quantile g-computation and weighted quantile sum regression. Both methods confirmed a positive overall mixture effect, meaning the combined burden of rare earth elements raised the risk of both cognitive and psychomotor developmental delays. Intriguingly, the two methods identified different dominant contributors. Ytterbium emerged as the primary driver of cognitive developmental delay, while cerium played the leading role in psychomotor delay, hinting that individual rare earth elements may exert distinct biological effects even within a chemically similar family.

The study’s most innovative move came next. Rather than treating metabolites as isolated signals, the researchers applied weighted gene co-expression network analysis, a technique originally developed for genomics, to the cord blood metabolomic data. Using a soft-thresholding power of 5, which produced a network with strong scale-free topology, the team clustered thousands of metabolites into thirteen color-coded modules representing coordinated metabolic networks. This approach allowed them to ask which entire biological pathways, rather than individual molecules, were perturbed by prenatal rare earth exposure.

Two modules stood out. Prenatal rare earth element exposure was consistently associated with perturbations in metabolic modules enriched in lysophospholipids and phosphatidylethanolamines, two classes of phospholipids that are fundamental building blocks of cell membranes. These molecules are especially important in the developing brain, where membranes are being rapidly assembled and remodeled as neurons grow and form connections. The finding suggests that rare earth elements may interfere with fetal neurodevelopment by scrambling the lipid architecture on which brain construction depends.

Crucially, the association was more than correlational. Mediation analyses demonstrated that the lysophospholipid and phosphatidylethanolamine modules partially mediated the link between prenatal exposure and increased risk of neurodevelopmental delay. In other words, part of the statistical pathway from rare earth exposure to developmental impairment runs through these disrupted lipid networks. The identification of a plausible biological mechanism elevates the findings from an observational association toward a more causal interpretation, though the researchers note that mediation captures only a portion of the overall effect and other pathways likely remain to be discovered.

The implications ripple outward in several directions. For public health officials, the study strengthens the case for including rare earth elements in routine risk assessments during pregnancy, a step that has lagged far behind their growing environmental presence. As global demand for these metals surges with the green energy transition and the proliferation of electronic devices, exposure levels in ordinary populations may continue to climb. The study also points toward potential interventions: if phospholipid disruption is a key mechanism, researchers could eventually explore whether nutritional or pharmacological strategies that support healthy lipid metabolism during pregnancy might buffer developing brains against environmental insult.

For the families in Wuhan whose participation made the study possible, the research offers no easy answers, since rare earth exposure is diffuse and difficult for individuals to avoid. But it adds an urgent data point to a larger conversation about the hidden costs of the technologies that define modern life. The metals that power our digital world are now demonstrably reaching the next generation before they take their first breath, and the developing brain appears to register their presence in ways we are only beginning to measure. As the authors conclude, the findings highlight the need for health risk assessment of rare earth element exposure during pregnancy, and they provide early clues to intervention targets that could protect children before the damage is done.

Subject of Research: Prenatal rare earth element exposure and its association with neurodevelopmental delay and phospholipid metabolic disruption in children

Article Title: Cord blood metabolic network profiles link prenatal rare earth element exposure to neurodevelopmental delay in 2-year-old children

Article References: Xie, Y., Qiu, L., Fang, X., Cao, Z., Li, S., Gong, H., Tan, T., Wang, J., Li, Y., Xu, S., Xiao, H., Zhou, A., & Xia, W. (2026). Cord blood metabolic network profiles link prenatal rare earth element exposure to neurodevelopmental delay in 2-year-old children. BMC Medicine. https://doi.org/10.1186/s12916-026-05306-9

Image Credits: AI Generated

DOI: 10.1186/s12916-026-05306-9

Keywords: rare earth elements, prenatal exposure, neurodevelopmental delay, metabolomics, cord blood, phospholipid metabolism, WGCNA, Bayley Scales, birth cohort, cognitive development, psychomotor development, environmental health

The Micalizzi study stands out because of an unusual longitudinal resource spanning seventeen years and drawing on two linked investigations. The first, known as Baby’s Breath, was a pregnancy intervention designed to reduce maternal smoking and infants’ exposure to secondhand smoke during the perinatal period. The second, Pathways, was a randomized controlled trial that enrolled 738 women and later followed 109 mother-child pairs from the perinatal study into adolescence. During the perinatal phase, mothers reported their own smoking and their infants’ exposure to tobacco smoke when the children were six months old, and these reports were checked against bioverified cotinine levels. Cotinine, a metabolite of nicotine, is widely regarded as the biomarker of choice for measuring tobacco smoke exposure because it can be detected in saliva, blood, and other biological samples and provides an objective chemical record of recent nicotine intake. Years later, when the children had reached adolescence, the same mothers were asked to recall, retrospectively, how much smoke their infants had been exposed to.

The results reveal a striking asymmetry in the reliability of human memory and self-report. When mothers reported their own smoking at six months postpartum, their answers concorded strongly with their own salivary cotinine levels, suggesting that adults can accurately describe their personal habits when those habits have already been openly acknowledged. But the picture changed dramatically for the infants. Maternal reports of infant smoke exposure did not align with the infants’ own cotinine levels, and the retrospective accounts given during adolescence were likewise inconsistent with the bioverified measurements taken years earlier. Most tellingly, the researchers identified a pattern of systematic bias that depended on whether mothers had acknowledged or denied exposure. When mothers admitted that their infants had been around smoke, their reports were largely reliable. When mothers reported no exposure at all, discrepancies with infant cotinine levels emerged that pointed toward underreporting or misclassification. In other words, denial, not memory alone, appears to be the primary corrupting force in the record.

This pattern has profound implications for developmental neurotoxicology, a field that depends heavily on maternal report to reconstruct exposures that occurred before birth or in early infancy. Stigma and social undesirability exert powerful pressure on what parents are willing to say, and the passage of time degrades memory in ways that are neither random nor benign. The commentary emphasizes that these forces are not unique to tobacco. Alcohol, marijuana, cocaine, methamphetamines, and even prescribed drugs such as opiates all carry social weight that can shape reporting, and all have been implicated in media accounts and research as potential threats to children’s development. Wherever disclosure carries a cost, whether legal, social, or emotional, the integrity of self-reported exposure data comes into question, and researchers who rely on such data without biochemical verification risk building their conclusions on systematically biased foundations.

Converging evidence from other studies reinforces the concern. In a large cohort of polydrug-exposed infants, researchers used multiple measures of exposure, including infant and maternal urine, infant meconium, and a Timeline followback interview. Concordance between interview data and biomarkers was high for cocaine exposure, but the two methods disagreed about the amount of exposure: mothers self-reported lighter use while meconium measurements indicated heavier use. Notably, the mothers in that study were all volunteers who had already been identified by their drug use, a circumstance that, as in the Micalizzi study, likely increased the reliability of their reports. The lesson is sobering: even under favorable conditions, with motivated and already-identified participants, quantitative discrepancies persist between what mothers say and what biology reveals.

The discrepancies become even more dramatic when bioverification occurs outside the supportive context of an intervention study. In a cohort drawn from the Health Outcomes and Measures of the Environment Study, a large prospective birth cohort, researchers found significant gaps between maternal self-report of smoking during pregnancy and serum cotinine levels measured in the same women. Only 12 to 26 percent of mothers reported active smoking or combined active and passive exposure, yet cotinine was detectable in 68.6 percent of maternal serum samples collected at sixteen weeks of gestation, and in an even higher percentage of child serum samples. Maternal serum levels were also the best predictors of childhood wheezing, a common respiratory outcome. Had the researchers relied on self-report alone, they would have substantially underestimated the health risks posed by tobacco smoke exposure, quietly erasing a large fraction of the exposed population from their analyses.

Timing of assessment adds another layer of complexity. In a large prospective study of prenatal alcohol exposure, mothers reported their pregnancy drinking, drug use, and smoking both during pregnancy and again four years after delivery. Retrospective reports of drinking were higher than antenatal reports, yet the antenatal accounts more accurately predicted infant neurobehavioral outcomes, suggesting that memory does not simply fade but actively reconstructs the past. For smoking, antenatal and retrospective reports were highly correlated and both predicted some cognitive outcomes, even without biomarkers. The authors of that study stressed the importance of measuring substance use during pregnancy itself, because most women decrease their use once they realize they are pregnant, and many biomarkers or interviews conducted at birth capture only recent use. A single measurement at delivery can therefore miss the critical early weeks of gestation when exposure may have been highest.

Some exposures resist biomarker measurement altogether. Prenatal alcohol exposure remains uniquely difficult to detect because no valid or reliable biomarker currently exists, although promising work has measured fatty acid ethyl esters in infant meconium and linked their presence and quantity to maternal reports and child outcomes. Other candidate biomarkers include gamma-glutamyltransferase, carbohydrate-deficient transferrin, ethyl glucuronide, ethyl sulfate, and mean corpuscular volume, each with limitations in sensitivity and detection window. For most other substances of concern, reliable biomarkers do exist, but they are scattered across an array of biological matrices: saliva, buccal cells, urine, finger and toenails, deciduous teeth, meconium, stool, hair, blood, breast milk, and cord blood. The ongoing Healthy Brain and Child Development study chose to collect multiple maternal and child biomarkers at multiple points in pregnancy and postpartum, precisely because each biomarker differs in breadth of detection window, substance sensitivity, patient burden, cultural acceptability, cost, and feasibility.

The modern exposure landscape is also far more complicated than it was when earlier cohorts were assembled. Polysubstance use among pregnant women is increasing, and prescription medications, both as prescribed and illicitly obtained, including stimulants, antidepressants, benzodiazepines, gabapentin, and non-benzodiazepine hypnotics, are increasingly used during pregnancy. The legalization of cannabis for medical and recreational purposes has led to greater prenatal exposure, and one large health maintenance organization study found that smoking during pregnancy clustered with alcohol and caffeine use. Because multiple substances can produce additive or synergistic adverse effects, or even moderating beneficial effects, study designs must account for these combinations. Beyond drugs, the neurotoxicant exposome, the constellation of chemical pollutants including lead, cadmium, arsenic, phthalates, polychlorinated biphenyls, and polybrominated diphenyl ethers, is now recognized as an important determinant of health and development, with several of these contaminants more prevalent in low-income homes such as those in the present study.

The clinical and methodological implications of the Micalizzi findings are clear. Neither biomarkers nor self-reports alone are sufficient; both are critical to improving the accuracy of understanding the occurrence of, and the thresholds for, prenatal and postnatal impacts of substances such as environmental tobacco smoke. The commentary alerts researchers to a specific threat to validity: bias and misclassification are most likely when exposure is denied, meaning that the absence of reported exposure should never be treated as the absence of exposure. The paper also offers strategies to reduce uncertainty in cases of denial, including the use of novel biomarkers, sensitivity analyses, and combining self-report with third-party interviews to develop more accurate inferences about exposure thresholds and outcomes. For a science that seeks to protect the developing brain, the message is simple and demanding: trust what mothers say, but always verify it against the chemistry of the body.

Subject of Research: Validity of maternal self-report versus biomarker-based assessment of prenatal and infant substance exposure

Article Title: Trust but verify…the importance of multimethod and biomarker assessments of prenatal substance exposures

Article References: Singer, L. T. (2026). Trust but verify…the importance of multimethod and biomarker assessments of prenatal substance exposures. Pediatric Research. https://doi.org/10.1038/s41390-026-05544-w

Image Credits: AI Generated

DOI: 10.1038/s41390-026-05544-w

Keywords: environmental tobacco smoke, cotinine, biomarkers, maternal self-report, prenatal exposure, retrospective recall, developmental neurotoxicology, secondhand smoke, polysubstance use, pediatric health, exposure misclassification, public health

Phthalates are a class of synthetic chemicals used to make rigid plastics flexible and durable, and they are found in an enormous range of everyday products, including food packaging, medical devices, vinyl flooring, and children’s toys. Over the past two decades, a growing body of epidemiological and laboratory evidence has linked phthalate exposure to an increased risk of premature birth, infertility, and other health concerns, prompting manufacturers to seek alternatives. DINCH emerged as one of the most prominent of these substitutes and has been marketed as a plasticizer with a more favorable safety profile. The new study suggests, however, that the assumption of safety may deserve closer scrutiny, because higher maternal DINCH levels were consistently associated with reduced newborn size, a marker that clinicians consider an important early indicator of lifelong health risk.

The scale of the association was quantified precisely by the research team. Every tenfold increase in exposure to DINCH corresponded to a 27-gram reduction in newborn birth weight. While 27 grams may appear modest in isolation, the researchers emphasize that even small differences in birth size can matter significantly at the population level. Fetal growth problems can raise the risk of heart disease, learning difficulties, obesity, and other conditions that echo into adolescence and adulthood, a phenomenon known as the developmental origins of health and disease. Lead author Leonardo Trasande, MD, MPP, the Jim G. Hendrick, MD, Professor of Pediatrics at NYU Grossman School of Medicine, noted that a chemical promoted as a safer replacement for phthalates and other plasticizers may affect how babies grow in the womb, and that even small shifts in birth size can carry consequences across the life course.

The study drew its data from the Environmental Influences on Child Health Outcomes program, a National Institutes of Health initiative that tracks families’ health from pregnancy through childhood. One of the strengths of this cohort is its diversity: participants came from many different racial, ethnic, and economic backgrounds across the United States, making the results more representative of the nation than those of many earlier studies, which often relied on smaller or more homogeneous samples. Urine samples were analyzed for three DINCH breakdown products, the metabolites that the body produces as it processes and excretes the chemical. Some participants provided more than one sample, which allowed the researchers to track exposure across different trimesters of pregnancy, a methodological advance that distinguishes this work from prior analyses.

Indeed, the researchers report that this is the first study to measure DINCH at different times during pregnancy, and the timing of exposure proved to be an important variable. DINCH exposure during the third trimester was more strongly tied to lower birth weight for gestational age than exposure earlier in pregnancy, a pattern that aligns with the biology of late gestation, when fetal growth accelerates rapidly and nutrient and oxygen transfer through the placenta becomes especially critical. The analysis also accounted for other factors known to influence birth size, including the mother’s age, education, and number of previous pregnancies, strengthening the case that the observed associations are not simply artifacts of confounding.

The results revealed notable patterns beyond overall weight. Babies whose mothers had higher levels of DINCH in their urine were more likely to be classified as small for gestational age, a clinical designation applied when a newborn’s weight falls below the 10th percentile for babies born at the same stage of pregnancy. Sex-specific differences emerged as well: boys showed greater differences in birth length, while girls were more likely to be small for their gestational age. Between 50 percent and 70 percent of the pregnant women in the study had measurable levels of a DINCH by-product in their urine, indicating that exposure to this substitute plasticizer is widespread in the American population rather than confined to a narrow subset of consumers.

Mechanistically, laboratory studies in animals and human cells offer clues about how DINCH might influence fetal development. These studies suggest that when DINCH breaks down in the body, its by-products can interfere with hormones that guide fetal development and trigger inflammation that may affect how nutrients and oxygen reach the baby. Together, these effects may contribute to pregnancy complications such as reduced fetal growth, high blood pressure during pregnancy, and early labor. A small analysis of pregnant women undergoing fertility treatment has also linked higher DINCH exposure to an increased chance of preterm birth, although that particular finding was not observed in the current report, leaving the question of preterm delivery open for further investigation.

The study also raised concerns about disparities in exposure and health impacts. Mothers who were Hispanic or who had lower levels of education were more likely to have children affected by DINCH, according to the authors, a pattern consistent with broader evidence that chemical exposures are not evenly distributed across the population and that communities already facing structural disadvantages may bear a disproportionate share of environmental health burdens. Trasande argued that these results underscore the need for stronger oversight of chemicals used in food packaging and other household products, requiring that they be tested before they are introduced to the market rather than after they are connected to health concerns. He pointed to the global plastics treaty now under negotiation at the United Nations as a key opportunity to establish such policies.

The researchers were careful to note an important limitation: the analysis is observational and cannot prove that DINCH exposure directly causes smaller birth size. Observational studies of this kind identify associations within large populations, and while the team controlled for many known determinants of birth size, residual confounding remains a possibility in any study of environmental exposures. Nonetheless, the convergence of human epidemiological data with laboratory evidence of endocrine interference and inflammatory effects strengthens the biological plausibility of the findings and adds DINCH to the growing list of plastic additives whose health profiles warrant reexamination.

Looking ahead, the study authors plan to examine other plasticizers currently being used as alternatives to phthalates and to study in more detail how DINCH may slow fetal growth. Senior author Taylor Etzel, PhD, of Johns Hopkins University led the work alongside Trasande, with contributions from researchers at NYU Langone, RTI International, Northeastern University, Rutgers University, Johns Hopkins, the University of Colorado Anschutz, Emory University, Columbia University, the University of Michigan, Penn State University, the University of California, San Francisco, Dartmouth College, Wayne State University, the University of Washington, the University of Illinois at Urbana Champaign, and the University of North Carolina at Chapel Hill. Funding was provided by the National Institutes of Health’s Environmental Influences on Child Health Outcomes program. In the meantime, Trasande suggested that families concerned about plastic additives can talk with their healthcare providers and consider practical steps that may reduce exposure, while the scientific and policy communities continue to evaluate whether the replacements for yesterday’s problem chemicals are solving the problem or simply relocating it.

Subject of Research: Effects of prenatal exposure to the plasticizer DINCH on fetal growth and birth outcomes

Article Title: Exposure to ‘safer’ plastic additive during pregnancy linked to smaller birth size

Article References: Exposure to ‘safer’ plastic additive during pregnancy linked to smaller birth size. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: DINCH, phthalates, plasticizers, prenatal exposure, birth weight, fetal growth, endocrine disruption, ECHO program, Environment International, NYU Langone, plastics treaty, environmental health

Phthalate esters are among the most widely produced plasticizer families in the world. They are added to polyvinyl chloride and countless consumer goods—food packaging, cosmetics, personal care products, medical devices, floor coverings, and nail polish—to make rigid plastics flexible and durable. Because phthalates are not chemically bound to the polymer matrix, they leach, migrate, and evaporate into food, dust, water, and air. Decades of toxicological work have classified several of them as endocrine-disrupting chemicals, capable of interfering with hormone signaling, reproductive development, and metabolic regulation. Regulatory agencies in the European Union and the United States have restricted a series of the most concerning compounds, including DEHP, DBP, BBP, and DiBP, particularly in toys and childcare articles, prompting industry to pivot toward alternative plasticizers such as terephthalates and adipates.

That pivot is precisely what makes the new data so striking. The most prevalent plasticizer detected across all four maternal and fetal matrices was DEHT, or di(2-ethylhexyl) terephthalate, a structural isomer of the restricted DEHP that is widely promoted as a safer replacement. DEHT recorded the highest geometric mean concentration in urine at 403.7 micrograms per kilogram, followed by placenta at 318.6 micrograms per kilogram, blood at 304.5 micrograms per kilogram, and amniotic fluid at 275.0 micrograms per kilogram. In other words, a chemical introduced to reduce risk is now the dominant plasticizer burden in pregnant women, and it is not staying in the mother. Its presence in amniotic fluid—the liquid bathing the fetus—demonstrates that substitution has not eliminated fetal exposure, it has changed the chemical profile of that exposure.

Among the classical phthalates, the short-chain compounds told their own story. Diisobutyl phthalate (DiBP) showed the highest concentrations in placental tissue, at 195.8 micrograms per kilogram, and in urine, at 226.0 micrograms per kilogram, indicating both substantial body burden and efficient renal clearance. Dimethyl phthalate (DMP) and diethyl phthalate (DEP), lower-molecular-weight esters commonly found in cosmetics, fragrances, and personal care formulations, were mainly detected in amniotic fluid, at 128.2 and 64.8 micrograms per kilogram respectively. The distribution pattern is chemically meaningful: smaller, more water-soluble molecules tend to partition differently across biological membranes than bulkier, lipophilic ones, and their accumulation in amniotic fluid suggests they can traverse the placental barrier and equilibrate within the fetal compartment.

The placenta is often described as a protective shield, but pharmacologically it behaves more like a semi-permeable membrane governed by physicochemical rules. Molecular size, lipophilicity, ionization state, and protein binding all determine whether a compound crosses by passive diffusion, facilitated transport, or is retained. Plasticizers, being moderately lipophilic and of low molecular weight, are well positioned to cross. The Tunisian team’s measurements confirm this: substantial amounts of both phthalate and non-phthalate plasticizers were found on the fetal side of the barrier. Although the renal system contributes significantly to elimination—reflected in the high urinary concentrations of DEHT and DiBP—excretion is evidently not fast enough to prevent transplacental transfer during pregnancy.

The health implications of prenatal exposure are the subject of a growing and sobering literature. Phthalates have been linked in epidemiological and experimental studies to altered reproductive development, preterm delivery, changes in fetal growth parameters, and disruption of placental function-related genes. Research on the placental methylome and transcriptome suggests that phthalate exposure during the first trimester can reprogram gene regulation at a critical developmental window. Experimental work has also documented oxidative damage and suppression of the Wnt/β-catenin signaling pathway in placental tissue following dibutyl phthalate exposure. For the non-phthalate alternatives, the toxicological record is thinner but increasingly concerning; recent in silico and in vitro studies have flagged diisobutyl adipate, one of the compounds detected in this cohort, for potential lipid metabolism-disrupting effects.

Exposure sources for pregnant women are pervasive and difficult to avoid. Phthalates migrate from PVC food packaging into fatty foods, leach from bottled beverages, and contaminate spices, herbs, and dairy products, as previous surveys of Tunisian and Mediterranean markets by some of the same research groups have documented. Cosmetics and personal care products contribute dermal exposure, with DEP in particular a common ingredient of fragranced formulations. Indoor dust carries plasticizers shed from floorings, wall coverings, and consumer goods, while medical devices can deliver direct doses to vulnerable patients. The Monastir cohort, drawn from middle-class households, underscores that this is not an exposure limited to industrial workers or heavily polluted environments—it is a background exposure affecting the general population of expectant mothers.

The study’s analytical approach deserves attention because measuring parent plasticizers in biological matrices is technically demanding. These compounds are rapidly metabolized in the body into monoester metabolites, which are the usual targets of human biomonitoring in urine. Detecting the parent compounds themselves in placenta, amniotic fluid, blood, and urine, at geometric means ranging from tens to hundreds of micrograms per kilogram, provides a snapshot of circulating chemical burden rather than merely of recent excretion. The multi-matrix design is what allows the exposure continuum to be reconstructed: chemicals present in maternal blood and urine, retained in placental tissue, and dissolved in amniotic fluid trace a pathway from external exposure to the fetal environment.

The authors argue that their findings support further evaluation of both phthalates and their substitutes, and the data give that call force. If DEHT, the flagship replacement, now dominates the exposure profile of pregnant women and penetrates the amniotic cavity, then regulatory success measured by the disappearance of restricted phthalates may mask a regrettable substitution problem, in which one hazardous chemical is swapped for another whose safety profile is unproven in humans. The researchers emphasize the need for improved exposure control, especially for vulnerable populations such as pregnant women and developing fetuses. For now, the study stands as a technical warning: the plastic chemistry of modern life does not stop at the placental barrier, and the burden of proof is shifting to the alternatives that industry hoped would close the chapter on phthalate risk.

Subject of Research: Occurrence and placental transfer of phthalate and non-phthalate plasticizers in maternal and fetal biological matrices

Article Title: Occurrence, distribution and potential sources of phthalate and non-phthalate plasticizers in maternal and fetal-related biological matrices

Article References: Toumi, D., Souaf, B., Bayoudh, A., Alibi, S., Spanò, I., Di Bella, G., Alminderej, F. M., Majdoub, H., & Mansour, H. B. (2026). Occurrence, distribution and potential sources of phthalate and non-phthalate plasticizers in maternal and fetal-related biological matrices. Environmental Geochemistry and Health, 48(16), Article 637. https://doi.org/10.1007/s10653-026-03540-x

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03540-x

Keywords: phthalates, plasticizers, DEHT, endocrine disruptors, prenatal exposure, placental transfer, amniotic fluid, human biomonitoring, GC-MS/MS, Tunisia, pregnancy, non-phthalate alternatives

Mercury is a non-essential, globally distributed toxic metal with no biological function, and its behavior in marine food webs makes it a particular concern for top predators. In aquatic ecosystems, inorganic mercury released from industrial sources, coal combustion, and artisanal gold mining is converted by microbes into methylmercury, an organic form that is readily absorbed by living tissue. Unlike many contaminants that dilute as they move up the food chain, methylmercury bioaccumulates in individual organisms and biomagnifies across trophic levels, meaning that animals at the top of the web, such as marine mammals, can carry body burdens orders of magnitude higher than the water they swim in. Because methylmercury crosses the placenta and the blood-brain barrier, developing fetuses are especially vulnerable to its neurotoxic effects.

The research team, led by Anaclara Roselli-Laclau of the Universidad de la República in Uruguay together with colleagues from Uruguay and Brazil, focused on two sympatric otariid species that breed side by side at Isla de Lobos but occupy different ecological niches: the South American sea lion (Otaria flavescens) and the South American fur seal (Arctocephalus australis). The researchers quantified total mercury, or THg, in two complementary matrices: hair from adult females and lanugo, the fine natal fur that pups grow in utero and shed in the weeks after birth. Sampling covered 11 mother-pup pairs of sea lions and 46 mother-pup pairs of fur seals, providing an unusually direct way to examine maternal transfer because both members of each pair were analyzed.

The results revealed a striking contrast between the two species. Adult female sea lions averaged 30.5 micrograms of mercury per gram of hair on a dry weight basis, with a standard deviation of 9.3, while female fur seals averaged just 5.7 micrograms per gram, with a standard deviation of 3.4. The pattern was mirrored in their offspring: sea lion pups averaged 25.3 micrograms per gram of lanugo, compared with only 4.4 micrograms per gram in fur seal pups. In other words, sea lions at this colony carried roughly five to six times more mercury than their fur seal neighbors, and the concentrations measured in sea lion pups rank among the highest ever recorded for pinnipeds anywhere in the world.

This interspecies gap is best explained by differences in diet and foraging ecology. Sea lions from Uruguayan colonies are known to feed at higher trophic positions and in waters closer to the Río de la Plata estuary, a system influenced by both natural and anthropogenic metal inputs, while fur seals tend to forage further offshore on prey lower in the food web. Because methylmercury biomagnifies with each step in the food chain, a predator eating larger, older, more predatory fish accumulates substantially more of the metal than one feeding on small pelagic species. Previous work by the same group had already linked trophic habits to bioaccumulation in these two otariids, and the new mother-pup data extend that picture to the earliest stage of life.

Perhaps the most consequential finding is that mercury was detectable in lanugo at all. Lanugo is formed entirely before birth, so any mercury it contains must have been transferred across the placenta from the mother during gestation. The presence of THg in this prenatal fur therefore provides direct evidence of prenatal mercury exposure in both species, confirming that placental transfer, and not only lactation, is a significant route by which these animals hand their contaminant burden to the next generation. This aligns with earlier studies on Baltic grey seals and northern elephant seals, which documented transplacental mercury transfer, but the Uruguayan data add a South Atlantic baseline for two species that had been comparatively understudied.

Statistical modeling showed that pup mercury concentrations were positively associated with maternal concentrations in both species, which is exactly what one would expect if the pup’s prenatal fur faithfully reflects the mother’s body burden during pregnancy. However, the strength of that relationship differed dramatically between the species. In sea lions, the final model explained 75 percent of the variance in pup THg, a remarkably tight fit that suggests maternal levels are the dominant driver of pup exposure in this species. In fur seals, by contrast, the model explained only 20 percent of the variance, indicating that other factors, such as individual variation in foraging behavior, gestation timing, or physiological processes governing mercury mobilization, play a much larger role in shaping how much of the metal reaches each fetus.

The models also uncovered a sex effect that was present in one species but absent in the other. Among sea lions, male pups had lower mercury concentrations than female pups for a given maternal mercury level, a pattern that could reflect sex-specific differences in prenatal growth, body composition, or maternal investment, since male otariid pups are typically larger and may dilute their contaminant burden across more tissue mass. No such sex effect was detected in fur seals. The authors note that this kind of species-specific nuance matters for anyone hoping to use pup fur as a shortcut for monitoring adult contamination, because the relationship between mother and pup is not uniform across species or even between the sexes within a species.

That leads to the study’s central practical message: pup lanugo is not a reliable quantitative proxy for the mercury concentration of an individual mother. The variability in the mother-pup relationship, especially in fur seals, is too great to back-calculate a specific female’s burden from her pup’s fur. But the researchers argue that lanugo remains valuable in a different way. Because it can be collected from pups with minimal disturbance, without immobilizing or even closely approaching adult females, it offers a minimally invasive matrix for characterizing prenatal mercury exposure and for tracking broader species-level and population-level patterns over time and across geography. For colonies that are difficult to sample intensively, this could transform monitoring programs that would otherwise require invasive procedures on protected animals.

The broader implications extend beyond the South Atlantic. Marine mammals are widely regarded as sentinel species for ocean and human health, and elevated mercury in newborn sea lions signals that contamination in the southwestern Atlantic food web is reaching the most sensitive life stages of long-lived apex predators. Mercury exposure in young mammals has been linked in laboratory and field studies to impaired immune function, altered lymphocyte proliferation, and neurodevelopmental deficits, and similar concerns have been raised for harbor seal pups and Steller sea lion calves elsewhere. As mercury continues to enter the ocean from atmospheric deposition and from gold mining in the Amazon basin and beyond, studies like this one provide the baseline data needed to detect change, identify the species and populations most at risk, and inform international efforts, such as the Minamata Convention, to curb the flow of this persistent neurotoxin into marine ecosystems.

Subject of Research: Maternal-to-pup transfer of total mercury in South American sea lions and fur seals measured through maternal hair and pup lanugo

Article Title: Maternal–Pup Mercury Relationship in South American Sea Lions and Fur Seals

Article References: Roselli-Laclau, A., García-Alonso, J., Valdés, A., Freitas-Souza, M., Almeida, M. G., de Rezende, C. E., & Franco-Trecu, V. (2026). Maternal–Pup Mercury Relationship in South American Sea Lions and Fur Seals. Archives of Environmental Contamination and Toxicology, 91(3), Article 23. https://doi.org/10.1007/s00244-026-01227-z

Image Credits: AI Generated

DOI: 10.1007/s00244-026-01227-z

Keywords: mercury, South American sea lion, South American fur seal, pinnipeds, lanugo, prenatal exposure, biomagnification, ecotoxicology, marine mammals, Uruguay, maternal transfer, heavy metals

The investigation began with an epidemiological signal. The researchers conducted a retrospective analysis of 5,299 pregnancies and found that maternal exposure to elevated ozone concentrations during the middle and late stages of gestation was associated with markers of maternal immune activation, including increased risks of neutrophil and monocyte abnormalities. Maternal immune activation, often abbreviated MIA, is a well-documented phenomenon in immunology: when a pregnant mother’s immune system is provoked by infection or inflammatory stimuli, the resulting inflammatory state can shape fetal development in lasting ways. What makes the new work striking is that it links this activation not to a virus or bacterium, but to an environmental pollutant, and traces its consequences all the way down to the sugar decorations on antibodies passed from mother to child.

Epidemiological studies have previously hinted that prenatal oxidative stress—the biochemical wear caused by reactive oxygen species—correlates with heightened allergy susceptibility in children. Correlation, however, is not causation, and the authors of the new study set out to close that gap. Using an animal model in which pregnant dams were exposed to ozone to induce maternal immune activation, the team demonstrated that the offspring of these dams exhibited measurably heightened susceptibility to allergic responses, with male offspring showing the most pronounced effects. This sex bias is notable, because allergic disease epidemiology in humans also shows sex-dependent patterns, and the study offers a mechanistic thread that could help explain why.

The mechanistic heart of the paper lies in glycobiology, the study of the sugar chains attached to proteins. Antibodies of the immunoglobulin G class, or IgG, are not simply protein molecules; they carry N-linked glycans—branched sugar structures attached at specific asparagine residues in the Fc region—that profoundly influence how the antibody behaves. The composition of these glycans determines which Fc receptors the antibody engages on immune cells, and thereby whether an antibody-antigen complex triggers a calm clearance response or a full-blown inflammatory cascade. The researchers found that maternal immune activation disrupts two processes involving IgG: the transfer of maternal IgG across the placenta to the fetus, and the glycosylation machinery that decorates IgG in the neonate.

Specifically, the team identified perturbations in Mgat3-mediated N-acetylglucosamine, or GlcNAc, modifications. Mgat3 encodes an enzyme, N-acetylglucosaminyltransferase III, that adds a bisecting GlcNAc residue to N-glycans—a seemingly small chemical alteration with outsized immunological consequences. In the offspring exposed to maternal immune activation in utero, this glycosylation program was disturbed, and the perturbation preferentially activated IL-17 and TNF signaling in juvenile males. Interleukin-17 and tumor necrosis factor are pro-inflammatory cytokines central to neutrophil-driven inflammation and to several autoimmune and allergic pathologies, so their preferential activation provides a plausible route by which early-life glycan changes translate into inflammatory disease risk.

The story does not end in juvenility. The researchers traced a transcriptional circuit that sustains the altered glycosylation into adulthood. Downstream transcription factors c-Jun and c-Fos—components of the AP-1 complex, a classic node linking inflammatory signaling to gene expression—activate the gene Mgat4a in adulthood, which in turn sustains GlcNAc glycosylation of IgG. In other words, the glycan abnormality imprinted by prenatal ozone exposure is not a transient neonatal phenomenon; it is actively maintained throughout life by a self-perpetuating transcriptional program. This finding elevates the study from a description of a developmental insult to a demonstration of a durable molecular memory of prenatal environment.

The functional consequence of this sustained glycosylation is the most clinically resonant part of the work. The altered GlcNAc glycosylation of IgG was associated with enhanced affinity between IgG and FcγRIII, an activating Fc gamma receptor expressed on immune cells such as macrophages, neutrophils, and natural killer cells. When IgG bound to an allergen engages FcγRIII more avidly, the resulting cellular activation is stronger, and in the context of anaphylaxis—an acute, potentially lethal systemic allergic reaction—the inflammatory response becomes more severe. The offspring in the ozone-exposure model therefore did not merely produce more antibodies or respond to more allergens; their antibodies had been chemically retuned to provoke fiercer inflammatory reactions upon encounter with a trigger.

This chain of evidence—environmental exposure, maternal immune activation, disrupted IgG transfer and glycosylation, sex-biased cytokine signaling, transcriptional maintenance, and enhanced Fc receptor affinity culminating in worse anaphylaxis—represents an unusually complete mechanistic arc for a study bridging environmental science and immunology. The authors describe their work as connecting environmental epidemiology, immunology, and glycobiology, and the description is apt. Few studies have followed a single pollutant exposure from a population-level association in thousands of pregnancies down to a specific enzyme-mediated sugar modification on a specific antibody class, and then shown how that modification changes receptor binding and disease severity in a living animal.

The implications for public health are considerable. Ozone is a secondary pollutant formed when nitrogen oxides and volatile organic compounds react under sunlight, and climate change is expected to intensify ozone episodes in many regions. If the mechanisms identified in this study operate in humans as the epidemiological component suggests, then protecting pregnant people from ozone exposure becomes not merely a respiratory health measure but a developmental one, with the potential to reduce allergic disease burden in the next generation. The finding that male offspring are preferentially affected adds a further layer of nuance for risk assessment, since it suggests that the same exposure may produce sex-differentiated disease vulnerability.

Caveats remain, as they do in any study that combines human association data with animal experimentation. The retrospective epidemiological analysis establishes a link between gestational ozone exposure and maternal immune activation markers, but the causal chain was demonstrated experimentally in mice, and translating glycosylation biology across species will require further validation. Nevertheless, the study opens concrete research avenues: monitoring IgG glycosylation patterns in children born after high-ozone pregnancies, investigating whether Mgat3 and Mgat4a pathways can be therapeutically modulated, and testing whether reducing maternal inflammation during gestation can normalize offspring antibody chemistry. For a field that has long asked why allergic diseases keep rising despite stable genetic backgrounds, the answer emerging from Taiyuan is sobering: part of the risk may be written into the immune system before birth, in the language of sugars, by the air the mother breathes.

Subject of Research: How prenatal ozone exposure activates maternal immunity and alters offspring IgG glycosylation to increase allergy susceptibility

Article Title: Elevated ozone activates maternal immunity to drive offspring IgG-mediated anaphylaxis through IgG glycosylation alterations

Article References: Wu, X., Gong, Z., Tian, Y., Liang, X., Wu, M., Zhu, H., Zhang, J., Hu, Y., Li, B., Li, P., Ji, X., Yue, H., & Sang, N. (2026). Elevated ozone activates maternal immunity to drive offspring IgG-mediated anaphylaxis through IgG glycosylation alterations. Nature Communications. https://doi.org/10.1038/s41467-026-77756-x

Image Credits: AI Generated

DOI: 10.1038/s41467-026-77756-x

Keywords: ozone, air pollution, maternal immune activation, IgG, glycosylation, anaphylaxis, allergy, prenatal exposure, Mgat3, FcγRIII, IL-17, oxidative stress

The chemicals in question are ubiquitous in modern life. Phthalates, which make plastics flexible, appear in food packaging, pharmaceuticals, dietary supplements, and personal care products. Phenols, including bisphenol A, bisphenol S, parabens, benzophenone-3, and triclosan, are found in everything from water bottles and receipt paper to cosmetics and antibacterial soaps. Because these substances are metabolized and excreted within hours to days, they are classified as non-persistent, yet the near-constant stream of exposure means biomonitoring studies routinely detect them in more than 90 percent of pregnant women in the United States. That combination of ubiquity and biological transience is precisely what makes studying their health effects so challenging.

The scientific rationale for concern is grounded in developmental biology. During embryonic and fetal development, organogenesis and tissue differentiation are exquisitely sensitive to hormonal signals, and endocrine-disrupting chemicals can interfere with the hormonal regulation of metabolism and energy balance. Phthalates, for example, can activate nuclear hormone receptors, particularly peroxisome proliferator-activated receptors, which govern adipogenesis, lipid metabolism, and energy storage. Activation of PPAR-gamma in the developing fetus may promote adipocyte differentiation and alter the production of adipokines such as leptin and adiponectin, potentially predisposing offspring to altered adiposity trajectories after birth. Some phthalates also exhibit anti-androgenic and weakly estrogenic activity, disrupting hormone signaling in utero, and previous research has linked prenatal phthalate exposure to altered steroid hormone profiles in humans as well as adverse metabolic outcomes in animal models.

To interrogate these questions at scale, the research team, led by Dorothy Nakiwala of the University of Colorado Anschutz Medical Campus, drew on 586 mother-child pairs from three ECHO cohort sites: the PROTECT Study in Puerto Rico, which recruited between 2010 and 2018; the Healthy Start Study in Colorado, recruited from 2009 to 2014; and the Illinois Kids Development Study, recruited from 2013 to 2018. All births occurred between 2009 and 2020. Maternal urine samples collected during pregnancy were shipped frozen to the Centers for Disease Control and Prevention, where concentrations of the phenol and phthalate metabolites were quantified using established laboratory methods. Children’s weight and height were measured primarily during clinic visits, and body mass index was converted to sex- and age-specific z-scores using the CDC 2000 growth charts, with assessments occurring between ages two and five at a mean age of 3.96 years.

The methodological architecture of the study is where it distinguishes itself from much of the prior literature. Rather than relying on a single statistical approach, the researchers triangulated their findings using covariate-adjusted single-pollutant linear regression alongside two complementary mixture methods: Bayesian Weighted Quantile Sum regression and Bayesian Kernel Machine Regression. The BWQS approach collapses multiple correlated exposures into a single weighted index under the assumption of a monotonic dose-response relationship, while BKMR uses a kernel function to flexibly model non-linear and interactive exposure-response patterns without imposing such assumptions. Models were adjusted for child sex and age, maternal age at delivery, pre-pregnancy BMI, parity, maternal race, maternal education, and study site, with covariate selection guided by a directed acyclic graph. Exposures were modeled both as continuous, log-transformed variables and as tertile categories to allow detection of threshold effects.

The headline result was null. When the entire 23-chemical mixture was evaluated, neither BWQS nor BKMR identified a statistically significant association with childhood BMI z-scores. The BWQS posterior mean estimate for a one-tertile increase in the mixture index was −0.06, with a credible interval spanning zero, and sex-stratified estimates of −0.24 for boys and 0.03 for girls were similarly inconclusive. The BKMR overall risk function, comparing joint increases in all exposures from the 25th to the 75th percentile against the 25th percentile, showed a non-significant, non-linear relationship with wide uncertainty intervals. There was also no evidence of interactions among pollutants, meaning the effect of any single chemical did not change appreciably as levels of the others rose.

The single-pollutant analyses, however, told a subtler story. When exposures were treated as continuous variables, no significant associations emerged. But when chemicals were categorized into tertiles, non-monotonic patterns appeared. Mono-benzyl phthalate, a metabolite of benzyl butyl phthalate, showed an inverse association: children whose mothers fell in the highest exposure tertile had BMI z-scores 0.33 lower than those in the lowest tertile, with a 95 percent confidence interval of −0.60 to −0.06. Mono-ethyl phthalate, a metabolite of diethyl phthalate, showed the opposite tendency, with the second tertile associated with a BMI z-score 0.27 higher than the first. Most strikingly, among boys only, mono-n-butyl phthalate in the second tertile was associated with a BMI z-score 0.45 higher than the first tertile, a non-monotonic pattern in which the third tertile showed no significant elevation. Among girls, the mono-ethyl phthalate pattern mirrored the pooled results but did not reach statistical significance.

The researchers are careful to contextualize these effect sizes. A shift of 0.1 to 0.2 standard deviations in BMI z-score may not be clinically meaningful for an individual child, but at the population level, even modest average shifts can increase the proportion of children classified as overweight or obese. Given that prenatal exposure to phenols and phthalates is essentially universal, small average effects could translate into a meaningful public health burden. The inverse association with mono-benzyl phthalate, meanwhile, aligns with at least one prior study, and one hypothesis holds that certain phthalates may impair growth by selectively disrupting muscle development rather than promoting fat accumulation, which could explain why phthalate exposure sometimes correlates with lower rather than higher BMI. The positive associations with mono-ethyl phthalate and mono-n-butyl phthalate, both low molecular weight phthalates found in pharmaceuticals, supplements, and personal care products, echo earlier reports linking prenatal mono-ethyl phthalate exposure to higher BMI trajectories from ages two to fourteen.

The consistency of the null mixture findings with previous research is itself informative. Studies using BKMR by Güil-Oumrait and colleagues, Berger and colleagues, and Ouidir and colleagues similarly reported no significant associations between prenatal phenol-phthalate mixtures and BMI z-scores at ages ten, five, and three, respectively, while cumulative-exposure studies using weighted quantile sum approaches by Svensson and Montazeri and their teams also found null results. One plausible explanation lies in exposure misclassification: because these chemicals clear the body so rapidly, spot urine samples may not adequately represent exposure across an entire pregnancy, and random misclassification typically biases results toward the null. The authors also note that BMI, their primary outcome, reflects overall body size without distinguishing fat from lean mass, potentially masking specific adiposity pathways, and that residual confounding by dietary behaviors associated with packaged and processed food consumption cannot be excluded.

Looking forward, the study’s authors argue that future research should prioritize repeated biomonitoring throughout pregnancy to better characterize exposures that fluctuate substantially over time, along with adequate statistical power to evaluate sex-specific effects, longitudinal follow-up, and direct measures of body composition. They also emphasize that postnatal and concurrent childhood exposures deserve attention, particularly given the short biological half-lives of these compounds. For now, the message is one of calibrated caution: the strongest evidence to date finds no cumulative effect of prenatal phenol-phthalate mixtures on early childhood BMI, but suggestive non-monotonic and sex-specific signals for individual chemicals underscore that the obesogen hypothesis, and the chemistry of everyday products that underpins it, remains a question science has not yet closed.

Subject of Research: Prenatal exposure to endocrine-disrupting phenols and phthalates and early childhood body mass index

Article Title: Prenatal exposure to nonpersistent endocrine disruptors and early childhood BMI: single pollutant and mixture analyses from the ECHO Program

Article References: Nakiwala, D., Perng, W., Barrett, E. S., Niu, Z., Alshawabkeh, A. N., Meeker, J. D., Dabelea, D., Starling, A. P., for the ECHO Cohort Consortium, Smith, P. B., Newby, L. K., Adair, L., Jacobson, L. P., Catellier, D., McGrath, M., Douglas, C., Duggal, P., Knapp, E., Kress, A., … Smith, L. M. (2026). Prenatal exposure to nonpersistent endocrine disruptors and early childhood BMI: single pollutant and mixture analyses from the ECHO Program. Pediatric Research. https://doi.org/10.1038/s41390-026-05466-7

Image Credits: AI Generated

DOI: 10.1038/s41390-026-05466-7

Keywords: endocrine-disrupting chemicals, phthalates, phenols, prenatal exposure, childhood obesity, BMI z-score, ECHO Program, chemical mixtures, BKMR, BWQS, developmental programming, biomonitoring

The chemistry behind the concern is deceptively simple. PFAS molecules are built on a carbon backbone in which hydrogen atoms have been replaced by fluorine, and the carbon-fluorine bond is one of the strongest in chemistry. That bond confers extraordinary thermal, chemical, and biological inertness, which is exactly what made PFAS so attractive to industry: they repel oil, water, and grease, making them ideal for surface protectants, food packaging coatings, and aqueous film-forming firefighting foams. But the same indestructibility means the compounds do not break down in the environment or in the body. The two most historically prominent members of the family, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), were largely phased out after health concerns emerged in the early 2000s, yet their legacy persists in blood, food, and drinking water worldwide.

How long these chemicals actually linger in the human body has been quantified through serial blood analyses of retired 3M production workers. Those measurements yield biological half-lives of roughly three years for PFOA, about five years for PFOS, and nearly nine years for perfluorohexane sulfonic acid (PFHxS), with perfluorononanoic acid (PFNA) at slightly under two and a half years. Because exposure is rarely eliminated completely, apparent half-lives stretch even longer as the body continues to accumulate new doses. For a newborn, the arithmetic is far worse than for an adult. PFAS cross the placenta efficiently, so a pregnant woman shares her accumulated body burden with her fetus, and the compounds are then excreted in human milk, meaning an infant’s serum concentrations can greatly exceed the mother’s.

The review catalogs a strikingly broad range of adverse outcomes linked to prenatal and early-life exposure. The most extensively documented are preterm birth, low birth weight, and delayed fetal growth, findings echoed by multiple agency assessments. A recent ecological study from a PFAS-contaminated region of Italy found that women who gave birth there faced at least a 50 percent higher risk of preeclampsia and gestational diabetes, along with increased numbers of infants born small for gestational age. In later childhood, elevated prenatal exposure has been associated with increased body weight and body mass index, a connection reinforced by recent meta-analyses. Evidence also suggests possible links to congenital heart defects, supported by experimental demonstrations that PFOS disrupts heart development in mouse models, and to altered sex hormone concentrations in both boys and girls during and after puberty, including earlier peripheral puberty development in girls below nine years of age.

Endocrine disruption emerges as a unifying mechanism across many of these outcomes. The thyroid gland appears to be a particular target, with associations between elevated PFOA and PFOS exposure and thyroid disruption recognized since the court-mandated C8 investigations, and confirmed even at background exposure levels. Recent studies focused on pregnant women and newborns suggest thyroid toxicity may begin prenatally and remain detectable into adolescence. The stakes are high because thyroxine delivery is tightly coupled to early neurological development; even a marginal reduction in maternal thyroid hormone output is a concern, given that fetal brain development is exquisitely vulnerable to such deficiencies. PFAS have been detected in human cerebrospinal fluid and at low concentrations in brain tissue, and studies point to possible cognitive deficits, hyperactivity, and internalizing behaviors, although results on autism and ADHD remain variable across study designs.

Perhaps the most consequential findings concern the immune system. The National Toxicology Program classified both PFOS and PFOA as presumed human immunotoxicants in 2016, and subsequent evidence implicates PFHxS and PFNA as well. The critical data come from prospective studies of vaccinated children: in a landmark cohort of 587 seven-year-olds, a doubling of serum PFOS and PFOA concentrations was associated with an overall decrease of 50 percent or more in vaccine-specific antibody concentrations, meaning some children failed to reach clinically protective levels even after three or four vaccinations. Norwegian children with elevated PFOA, PFNA, and PFHxS showed significantly increased frequencies of common colds and gastroenteritis, and elevated prenatal exposure has been linked to increased hospitalizations for pneumonia in young children. Because the immune system also surveils and eliminates cancer cells, immunotoxicity may feed into carcinogenesis, and PFAS carry several additional key characteristics of carcinogens.

On cancer, the regulatory picture has hardened considerably. The International Agency for Research on Cancer classified PFOA as a possible human carcinogen in 2016 but upgraded it to Group 1, a known human carcinogen, in 2023, while placing PFOS in Group 2B. The U.S. Environmental Protection Agency now considers both PFOA and PFOS carcinogenic to humans. Substantial evidence links PFOA to kidney and testicular cancer, and associations have been reported for prostate, bladder, and breast cancer, with a large National Cancer Institute study finding clear associations specifically for hormone receptor-positive breast tumors. A recent study also suggested that prenatal PFOS and PFOA exposure might increase the risk of retinoblastoma in children, and PFAS exposure has been tied to increased numbers of metastatic lymph nodes in colorectal cancer patients.

Woven through the review is an indictment of industrial secrecy that delayed this scientific reckoning by half a century. 3M researchers documented the presence of PFOS and PFOA in fish as early as the 1970s, and internal documents show company scientists were aware of PFOA health risks as early as the 1960s. A 1978 monkey study demonstrated lethal toxicity and immune system lesions at high doses, yet no follow-up studies were reported. A 1993 internal document acknowledged preliminary evidence that PFOS transfers into the milk of lactating goats and was likely to do so in lactating human females, but the results were not published. DuPont and 3M recorded PFAS in the blood of pregnant workers and newborns by 1980, and unusual malformations were observed at childbirths among exposed female workers, yet women were returned to PFOA-exposed work areas the following year. A published worker study by 3M authors omitted extensive draft results without p values, and the review’s author has characterized the discrepancy as possible scientific dishonesty; the article remains unretracted and has been cited more than 300 times.

Regulatory responses have lagged but are now accelerating dramatically. The EPA’s drinking water advisory for PFOA and PFOS fell from 400 parts per trillion in 2009 to 70 ppt in 2016, and interim advisories issued in June 2022, based on childhood immunotoxicity, imply chronic reference doses corresponding to just 0.004 ppt for PFOA and 0.02 ppt for PFOS, with enforceable limits proposed at 4 ppt and maximum contaminant level goals of zero. Over less than two decades, recommended exposure limits have dropped by more than a thousandfold, a strengthening the review describes as highly unusual. The European Union has announced a proposal to eliminate PFAS uses by 2030, describing the compounds as persisting in the environment longer than any other man-made substance.

The review closes with a forward-looking warning grounded in emerging biology. Experimental studies demonstrate that PFAS exposure can induce epigenetic changes inherited by future, unexposed generations, and although such transgenerational effects have not yet been confirmed for PFAS in humans, a recent study suggests polychlorinated biphenyls, another class of persistent organic pollutants considered obesogens like PFAS, may cause epigenetically mediated obesity across generations. Because most human evidence on PFAS is recent, the full toxicological picture, particularly for delayed outcomes of developmental exposure, remains incomplete, and today’s evidence may well underestimate the true extent of toxicity. The National Academies recommends clinical testing and follow-up for people with likely elevated exposure, a need that has largely gone unmet due to cost. Meanwhile, essentially everyone carries a PFAS body burden that will persist for years, and children will continue to be exposed at the most vulnerable moments of their lives. The review’s author argues that prudent public health decisions must be made now, despite incomplete evidence, because waiting for certainty is precisely the mistake that allowed seventy-five years of hidden harm.

Subject of Research: Pediatric and long-term health effects of prenatal and early-life exposure to persistent PFAS chemicals

Article Title: Pediatric effects of forever chemicals may last for a long time

Article References: Grandjean, P. (2026). Pediatric effects of forever chemicals may last for a long time. Pediatric Research. https://doi.org/10.1038/s41390-026-05366-w

Image Credits: AI Generated

DOI: 10.1038/s41390-026-05366-w

Keywords: PFAS, forever chemicals, pediatric health, prenatal exposure, immunotoxicity, endocrine disruption, breastfeeding, PFOA, PFOS, cancer risk, industrial secrecy, environmental regulation