Non-persistent chemicals are those that do not linger in the body for months or years, unlike legacy pollutants such as persistent organic pollutants or heavy metals. Instead, they are metabolized and excreted within minutes, hours, or days. This category includes an enormous range of compounds that pregnant women encounter daily: phthalates from food packaging and personal care products, parabens from cosmetics, benzophenones from sunscreens, bisphenols from plastics, antimicrobials from soaps, pesticide residues, flame retardant metabolites, polycyclic aromatic hydrocarbons from combustion sources, melamine derivatives, and aromatic amines from tobacco smoke and dyes. Because these chemicals clear the body so rapidly, urinary biomarkers essentially reflect very recent exposure. Whether a single measurement can stand in for exposure over an entire pregnancy depends entirely on how stable an individual’s concentrations remain over months of gestation.

The research team, led by Giehae Choi of Johns Hopkins University together with colleagues from institutions across the United States, tackled this question by analyzing three urine samples collected at different time points during pregnancy from 90 participants at three ECHO Cohort sites: New York, Illinois, and Puerto Rico. The scale of the chemical analysis was remarkable. The laboratory measured 154 analytes representing 163 chemicals across 12 chemical classes, using liquid chromatography-tandem mass spectrometry methods at the Wadsworth Center Human Health Exposure Analysis Resource laboratory. Of these, 84 analytes were detected in at least 20 percent of samples at a given site, providing sufficient data for variability analysis.

The central statistical tool was the intraclass correlation coefficient, or ICC, which quantifies how reliably a single measurement represents a person’s typical level across repeated measurements. ICCs range from 0 to 1, with values approaching 1 indicating that concentrations are highly stable within an individual over time, and values near 0 indicating that measurements are essentially unpredictable from one time point to the next. The team calculated ICCs for 58 analytes with detection frequencies above 60 percent, using log2-transformed concentrations standardized for urinary dilution by specific gravity. They also computed kappa statistics for 56 analytes with more moderate detection rates, assessing whether the mere presence or absence of a chemical above the detection limit was consistent across the three pregnancy samples.

The results were strikingly heterogeneous. ICCs ranged from −0.12 to 0.91, and the pattern of high versus low reliability differed substantially by cohort site for most chemicals. Only two analytes bucked this trend: benzophenone-1 and propyl paraben showed consistently high ICCs above 0.5 at all three sites, indicating stable exposure throughout pregnancy, while bisphenol F showed consistently low ICCs below 0.1 everywhere. Beyond these exceptions, the site-specific patterns were revealing. All parabens showed high reliability in Illinois but lower reliability in Puerto Rico and New York. Benzophenones were more stable in New York. Antimicrobials were more stable in Puerto Rico. Most phthalate and polycyclic aromatic hydrocarbon metabolites were moderately to highly reliable in Illinois but less so in Puerto Rico, while most aromatic amines showed the opposite pattern, with moderate to high reliability in New York but lower reliability in Illinois.

One of the study’s most technically insightful contributions was its analysis of how concentration levels relative to detection limits shape reliability estimates. The researchers hypothesized that measurement error exerts a proportionally greater influence when concentrations sit close to the limit of detection, obscuring the true rank-ordering of individuals. They therefore calculated the ratio of each analyte’s site-specific median concentration to its detection limit. Chemicals with median concentrations more than 50 times the detection limit tended to show greater stability across pregnancy, with notable exceptions among certain phthalate metabolites. This exception is itself informative: high concentrations paired with low ICCs suggest that exposure to the source products occurs sporadically but intensely, rather than continuously. Conversely, chemicals with median concentrations within tenfold of the detection limit generally showed lower ICCs, indicating that low-level measurements may reflect recent, sporadic exposures rather than a chronic exposure state. Benzophenone-8 provided a fascinating exception, maintaining moderate ICCs despite low concentrations, which the authors interpret as evidence of near-continuous low-level exposure.

The consistently high ICCs for benzophenone-1 deserve particular attention given the widespread use of benzophenones as ultraviolet filters in sunscreens, cosmetics, and personal care products, as well as their use as UV stabilizers in food packaging. Because these compounds do not bioaccumulate and have short biological half-lives, stable urinary concentrations can only mean that exposure itself is nearly continuous throughout pregnancy. Benzophenone-1 may appear more stable than benzophenone-3 partly because it is a major metabolite of benzophenone-3, integrating exposure from multiple sources, and because only a small fraction of benzophenone-3 is excreted unchanged in urine. The finding that benzophenone-3 was stable in Puerto Rico and New York but not Illinois may reflect seasonal differences in sunscreen use, a reminder that exposure context shapes biomarker reliability.

The site-specific differences also point to the influence of demographic, geographic, and behavioral factors on exposure chronicity. The New York site, where a majority of participants were classified in the high cotinine category suggesting substantial tobacco smoke exposure, showed moderate to high ICCs for aromatic amines such as aniline, which is found in tobacco smoke. Continuous exposure to tobacco through active or passive smoking could plausibly explain this stability. Similarly, moderate ICCs for melamine analogs like ammelide in New York may reflect ongoing exposure through contaminated foodstuffs and water. These observations suggest that individual, cultural, and structural factors, rather than pure physiology alone, determine whether a person’s chemical exposures remain constant or fluctuate across the months of gestation.

The practical consequences for environmental epidemiology are substantial. For the majority of non-persistent chemicals examined, a single pregnancy urine sample appears to represent exposure near the time of collection rather than exposure across the entire pregnancy. This matters enormously because different gestational windows carry different vulnerabilities: organogenesis in the first trimester, neurodevelopment throughout gestation, and fetal growth in later trimesters may each be sensitive to chemical exposures at distinct time points. If researchers link a single third-trimester measurement to a birth outcome and interpret it as reflecting first-trimester exposure, they risk substantial exposure misclassification, typically biasing estimated health associations toward the null. The authors note that simulation work suggests a chemical with an ICC below 0.2 would require more than 35 samples per person to keep this bias below 10 percent, an approach that is neither affordable nor practical for most studies.

Fortunately, the study outlines realistic alternatives. Researchers can incorporate validation sub-studies with repeated measurements and apply measurement error correction techniques such as regression calibration or simulation extrapolation. They can time urine collection to align with known critical windows of developmental susceptibility rather than defaulting to arbitrary collection schedules. They can collect multiple samples and pool them within each subject, which reduces assay costs while improving the representation of typical exposure. Or they can turn to alternative biospecimens such as hair, which integrates exposure over longer periods. The study also provides some of the first evidence on within-pregnancy stability for understudied chemical classes, including halogenated phenols such as the carcinogen pentachlorophenol, melamine and its analogs, and aromatic amines, filling critical gaps in the exposure science literature. As chemical production and consumer patterns evolve, the authors caution that reliability estimates from earlier studies may not transfer to current exposures, making ongoing characterization of biomarker variability an essential, not optional, component of rigorous environmental health research. For now, the message is clear: when it comes to non-persistent chemicals in pregnancy, one sample tells you where a woman was this week, not where she has been for nine months.

Subject of Research: Intra-individual variability of urinary non-persistent chemical biomarkers measured at three time points during pregnancy

Article Title: Intra-individual variability of urinary non-persistent chemical concentrations during pregnancy in the ECHO Cohort

Article References: Choi, G., Xun, X., Bennett, D. H., Meeker, J. D., Sathyanarayana, S., Schantz, S. L., Trasande, L., Watkins, D. J., Pellizzari, E., Li, W., Kannan, K., Woodruff, T. J., Buckley, J. P., & for the ECHO Cohort Consortium (2026). Intra-individual variability of urinary non-persistent chemical concentrations during pregnancy in the ECHO Cohort. Journal of Exposure Science & Environmental Epidemiology. https://doi.org/10.1038/s41370-026-00979-z

Image Credits: AI Generated

DOI: 10.1038/s41370-026-00979-z

Keywords: ECHO Cohort, pregnancy, non-persistent chemicals, urinary biomarkers, intraclass correlation, phthalates, parabens, benzophenones, exposure assessment, environmental epidemiology, aromatic amines, melamine

The scale of the issue stems from the sheer diversity of dye chemistry. Textile dyes are classified into broad families, including azo dyes built around nitrogen-nitrogen double bonds, anthraquinone dyes, indigoid dyes, and reactive, direct, disperse, acid, basic, vat, and sulfur classes defined by how they attach to fibers. Azo dyes dominate the market and dominate the concern, because under reducing conditions the azo linkage can cleave to release aromatic amines, some of which are carcinogenic or mutagenic. Surveys of clothing on the Swiss market have identified hazardous, non-regulated aromatic amines as cleavage products of azo dyes, and screening of garments sold in Brazil and Spain has confirmed human exposure to regulated aromatic amines through ordinary wear. The very tinctorial properties that make dyes valuable, their intense color at tiny concentrations, also mean that even minute discharges visibly pollute water and block light penetration, disrupting photosynthesis in aquatic systems far from the factory gate.

Environmental contamination follows multiple pathways. Dye-laden effluents discharged into rivers alter water color, reduce dissolved oxygen, and impair aquatic flora and fauna. Studies on freshwater microalgae such as Spirulina platensis show that dyes like methylene blue suppress growth and metabolism, while Congo red affects organisms across trophic levels, from microalgae and cladocerans to zebrafish embryos. Fish are particularly vulnerable: juvenile tilapia exposed to indigo dye show sub-lethal toxicity, and zebrafish embryo assays reveal that dyes such as Maxilon Blue 5G and Reactive Blue 203 cause acute toxicity and DNA damage during development, with some dyes producing teratogenic effects and biochemical and immunohistochemical changes. There is even evidence of bioaccumulation in the wild: toxic textile dyes have been detected accumulating in European eels caught in natural waters, demonstrating that these compounds move through food webs rather than remaining inert contaminants.

Soil and air are not spared. Textile effluents applied to or leaked into land degrade soil microbial communities, and experiments with the dye Red-S3B showed measurable harm to soil microbial activity and wheat yield, effects that could only be partially alleviated by organic amendments. Genotoxicity assessments of soils contaminated by textile waste confirm that dye residues can damage genetic material in soil organisms. Sludge from textile dyeing plants contains aromatic amines whose distribution and concentrations have been mapped in risk assessments across multiple Chinese facilities, and long-term printing and dyeing sludge landfills have been flagged in weighted comprehensive risk analyses. Even the air indoors matters: emissions from textile products contribute to indoor air quality concerns, and combustion of biological sludge from dyeing effluent treatment plants raises air pollution questions of its own. The review underscores that dye pollution is not a single-medium problem but a persistent, multi-compartment contamination.

For human health, the most direct route of exposure is the skin. Textile dye dermatitis has been documented for decades, with disperse dyes, used widely on polyester, identified as significant contact allergens. Patch testing has long been part of diagnosing these allergies, and clinical reviews describe allergic contact dermatitis arising from dyed fabrics as a current and ongoing clinical issue. Beyond the skin, the cleavage of azo dyes into aromatic amines creates systemic risk, and recent work has identified dye intermediates such as N-phenyl-2-naphthylamine and o-tolidine as novel environmental androgens with reproductive toxicity in male rats. Systematic evidence mapping efforts are now cataloguing the available hazard data for market-relevant azo dyes, and researchers have proposed priority control lists for azo dyes based on human health risk, ecotoxicity, and degradation product profiles. Regulatory frameworks, including the European Union’s REACH regulation and Commission Regulation No 552/2009, restrict certain azo dyes and other hazardous colorants, and voluntary standards such as Oeko-Tex Standard 100 push manufacturers toward safer chemistry, but the review stresses that many hazardous dyes remain outside regulation.

Measuring toxicity is itself a technical challenge, and the review devotes attention to the test systems used to judge whether a dye or its breakdown products are dangerous. Classical acute toxicity measures such as the LD50 remain in use for hazard communication, though their limitations are widely acknowledged. Modern ecotoxicology relies on batteries of biotests spanning multiple trophic levels: acute and chronic assays with the water flea Daphnia magna and the alga Raphidocelis subcapitata, zebrafish embryo models for developmental and genotoxic endpoints, human keratinocyte cell lines for dermal relevance, and phytotoxicity assays using seed germination and plant growth. In silico approaches, including molecular docking and computational toxicity prediction, increasingly complement laboratory work by screening enzyme-dye interactions and predicting metabolite hazards before experiments are run. The consistent lesson from the literature is that decolorization alone is not enough; a treated effluent can look clean while its metabolites remain toxic, so toxicity assessment must accompany every treatment claim.

That insight drives the review’s comparison of elimination technologies, which fall into three broad categories: physical, chemical, and biological. Adsorption remains the workhorse of physical treatment, and the past few years have produced a remarkable array of sorbent materials, from activated carbons derived from bio-based waste and water hyacinth to fly ash, Moringa seed waste, ostrich eggshell, graphene exfoliated from industrial graphite waste, chitosan polymers cross-linked with pillararenes, and magnetic nanoadsorbents engineered for high capacity and recyclability. Membrane processes, including nanofiltration and biomimetic porous membranes with sub-nanometer channel regulation, can both remove dyes and, in ceramic membrane systems, recover dyes and salts for reuse. Coagulation exploits molecular structure to aggregate direct dyes, and electrocoagulation, often integrated with electrochemical oxidation, adsorption, or nanofiltration, has been optimized through statistical designs to treat real textile effluents with recycled electrodes.

Chemical degradation aims higher than removal: the goal is mineralization, the complete conversion of dye molecules into carbon dioxide, water, and inorganic ions. Advanced oxidation processes dominate this space. Fenton and Fenton-like chemistry, which generate hydroxyl radicals from hydrogen peroxide catalyzed by iron, has been extended to heterogeneous catalysts, hydrochar bio-based catalysts, nickel converter slag, and even single-atom catalysts whose size-dependent activity is a frontier of materials chemistry. Photocatalysis has exploded as a research area, with semiconductor nanoparticles of zinc oxide, tin dioxide, titanium dioxide doped with terbium, copper ferrite composites on montmorillonite, carbon dots bound to palladium-ceria on zeolite, and g-C3N4 biochar composites activated by persulfate all demonstrating dye degradation under UV or visible light. Ozonation, plasma-generated ozone and nitric oxide, and electrochemical peroxidation round out the oxidative toolkit. Critically, recent studies pair these treatments with cytotoxicity and ecotoxicity assessments of the by-products, because incomplete oxidation can leave intermediates that are as hazardous as the starting dye.

Biological approaches offer the appeal of low cost and environmental compatibility, and the microbial world has proven remarkably resourceful at dismantling dye structures. Bacteria such as Pseudomonas aeruginosa, Bacillus firmus, Bacillus cohni, Ochrobactrum intermedium, Serratia marcescens, and Providencia stuartii degrade azo, anthraquinone, and cationic dyes, with transcriptome profiling revealing upregulation of benzoate degradation pathways during the process. Fungi are equally important: white-rot fungi such as Trametes hirsuta, Trametes versicolor, and Pleurotus ostreatus secrete laccases and peroxidases that decolorize structurally diverse dyes, and immobilized fungal biomass and enzyme systems, including horseradish peroxidase on magnetic-carbon-polymer supports and cationic cellulose aerogels, extend enzyme lifetimes for repeated use. A newly characterized dye-decolorizing peroxidase from Brevibacillus agri has been applied directly to real textile wastewater, and a metal-dependent hydrolase named MdeH from Buttiauxella sp. cleaves Congo red with defined mechanism. Metagenomics is now being translated into bioremediation strategy, identifying dye-degrading communities tolerant of the extreme salinity and pH typical of textile effluents, while genetically modified microorganisms and plant-based systems, from hairy roots of Ipomoea carnea and sunflower to duckweed and constructed phytobeds, demonstrate in situ detoxification verified by non-target toxicity screening.

The review’s concluding message is one of urgency and integration. No single technology currently wins across all criteria of efficiency, cost, toxicity of residues, and scalability, and the most promising real-world solutions are hybrid ones: sequential electrocoagulation, oxidation, and adsorption trains; combined adsorptive-photocatalytic composites such as biochar-supported copper-doped tungsten trioxide valorized from water hyacinth; and enzyme-nanoparticle pairings that couple degradation with verified detoxification. Techno-economic assessments and life cycle analyses are increasingly part of the evaluation, ensuring that a laboratory triumph does not become an environmental liability at scale. Prevention matters as much as cure, and greener dyeing strategies, from supercritical carbon dioxide dyeing of polyester-cotton blends and cationic colored nanospheres for clean cotton dyeing to microbial prodigiosin pigments and ionic liquid-assisted processes, aim to reduce the hazard before effluent is ever created. What the accumulated evidence makes unmistakably clear is that the colorful chemistry of modern textiles demands an equally sophisticated chemistry of cleanup, and that finding the best solution for textile dye risk to environment and human health is no longer optional but urgent.

Subject of Research: Environmental and human health hazards of synthetic textile dyes and technologies for their degradation and elimination

Article Title: Environmental and human health hazard of textile synthetic dyes and some solutions for their elimination

Article References: Stanescu, M. D. (2026). Environmental and human health hazard of textile synthetic dyes and some solutions for their elimination. Environmental Science and Pollution Research, 33(30), 15229-15252. https://doi.org/10.1007/s11356-026-38198-6

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38198-6

Keywords: textile dyes, azo dyes, water pollution, aromatic amines, toxicity, wastewater treatment, photocatalysis, biodegradation, adsorption, advanced oxidation, ecotoxicology, human health

The environmental stakes are considerable. Nitroaromatic compounds, which carry one or more nitro groups attached to an aromatic ring, are workhorse chemicals in agriculture, dyes, pesticides, and pharmaceutical manufacturing. Among them, 4-nitrophenol stands out: the United States Environmental Protection Agency classifies it as a Priority Pollutant because of its toxicity and carcinogenic properties. These compounds persist in water and soil, and because industrial activity keeps generating them, practical methods for degrading them are in constant demand. Converting a nitroarene into its corresponding aminoarene is an environmentally friendly route to detoxification, and doing so with a reusable solid catalyst under mild conditions is the gold standard the field is trying to reach.

The chemistry behind the reaction is well understood but hard to make fast. Sodium borohydride, the reducing agent used here, hydrolyzes in water and releases borohydride ions that donate hydrogen through deprotonation. That hydrogen must be adsorbed and dissociated on a metal surface before it can be handed to the nitroarene molecule. Thermodynamically, the reduction of 4-nitrophenol to 4-aminophenol is favorable, yet it stalls kinetically: without a catalyst, the negatively charged 4-nitrophenolate ion and the borohydride ions simply repel each other, and the reaction does not proceed even after hours. Metal nanoparticles solve this problem by providing active surfaces, but they come with their own weakness, namely a tendency to aggregate, which destroys their high surface area and kills their catalytic activity.

The Iranian team’s solution was to anchor the cobalt inside a covalent triazine framework, a class of porous organic polymer prized for its nitrogen-rich structure, chemical and thermal stability, and low density. The support, PD-CTF, was synthesized by reacting 1,4-phenylenediamine with cyanuric chloride in dimethyl sulfoxide and 1,4-dioxane, first at ice temperature and then under reflux at 100 degrees Celsius for 72 hours, yielding the brown polymer in 87 percent yield. Crucially, the researchers used a molar excess of cyanuric chloride, leaving residual reactive chlorinated groups on the framework, so the resulting network is an irregular cross-linked structure rather than a perfectly repeating lattice. Cobalt chloride was then added to a methanol dispersion of the polymer, and sodium borohydride reduced the metal salt in situ, embedding cobalt nanoparticles between the polymer layers in 95 percent yield.

A battery of characterization techniques confirmed the hybrid structure. Fourier transform infrared spectroscopy showed the disappearance of the carbon-chlorine bands of cyanuric chloride and shifts in the carbon-nitrogen vibrations, with changes in the 570 to 720 per centimeter region indicating that cobalt had been immobilized between the polymer layers. Powder X-ray diffraction revealed peaks matching hexagonal close-packed cobalt at 2-theta angles of 41.4, 44.8, and 47.1 degrees, alongside reflections from cobalt oxide phases that form naturally when reactive cobalt meets air. Electron microscopy delivered perhaps the most striking visual change: the bare polymer appears as irregular porous clusters, while the cobalt-loaded composite forms well-defined spheres averaging 38.4 nanometers in diameter. Energy-dispersive X-ray mapping confirmed carbon, nitrogen, and cobalt distributed throughout the material.

Porosity measurements told a subtler story. Nitrogen adsorption isotherms recorded at 77 kelvin showed that loading the cobalt reduced the pore volume from 0.1493 to 0.0622 cubic centimeters per gram and the estimated BJH pore diameter from 4.62 to 1.22 nanometers, consistent with metal particles partially blocking the polymer’s channels. Inductively coupled plasma analysis put the cobalt content at a remarkably high 45.6 percent by weight, or 7.74 millimoles per gram, while thermogravimetric analysis suggested a lower figure of about 27 percent, a discrepancy the authors attribute to the different physical principles behind the two methods. Notably, the composite was more thermally stable than the bare polymer, which the team credits to strong interactions between the cobalt species and the nitrogen-rich framework.

The catalytic tests were where the material earned its keep. Using 4-nitrophenol as the model substrate, the researchers found that neither the bare polymer nor sodium borohydride alone achieved any measurable reduction within 120 seconds. With 4 milligrams of PD-CTF@Co, however, the bright yellow 4-nitrophenolate peak at 400 nanometers collapsed and a new peak at 300 nanometers, characteristic of 4-aminophenol, rose to 97 percent conversion in just 120 seconds, with an apparent rate constant of 0.0293 per second. The team systematically optimized both the borohydride volume, settling on 0.5 milliliters of a 0.1 molar solution, and the catalyst dose, finding that 5 milligrams actually performed slightly worse than 4. The catalyst also handled 4-nitroaniline and 2-chloro-4-nitroaniline, converting 98.6 and 98.8 percent respectively in 300 and 240 seconds, with the slower aniline reductions likely reflecting partial blocking of active sites by the amino groups.

Two control experiments addressed the perennial worry about heterogeneous catalysts: is the activity really from the solid, or from cobalt leaching into solution? A hot filtration test, in which the catalyst was removed once the reaction reached roughly 50 percent conversion after 45 seconds, showed no further progress afterward, proving the immobilized cobalt does the work. Meanwhile, ICP-OES analysis of the filtrates after each cycle detected only trace cobalt leaching, 3.00 percent in the first run and falling below the detection limit by the fourth and fifth. The catalyst retained 95 to 97 percent of its activity over five consecutive reuse cycles, and the cobalt content of the recovered solid dropped only marginally, from 7.74 to 7.19 millimoles per gram.

The proposed mechanism is a tale of two partners working in concert. The nitrogen-rich triazine framework acts as a porous adsorption platform, concentrating nitroarene molecules near the active sites through pi-pi stacking between the aromatic rings of the polymer and the substrate, reinforced by hydrogen-bonding interactions with the framework nitrogen atoms. Meanwhile, the embedded cobalt nanoparticles activate the borohydride, generating reactive hydrogen species on their surfaces. The nitro group then undergoes stepwise reduction, first cleaving a nitrogen-oxygen bond to form a nitroso intermediate, then converting to a hydroxylamine, and finally desorbing as the aromatic amine product, which frees the sites for the next cycle. The close proximity of adsorbed substrate and activated hydrogen within the pores is what makes the hydride transfer so efficient.

Compared against previously reported catalysts for the same model reaction, including cobalt-manganese oxides, palladium confined in conjugated polymers, copper ferrites, and silver on alumina, PD-CTF@Co’s rate constant of 0.0293 per second and 120-second completion time are competitive, though the authors caution that differing reaction conditions make direct comparisons imperfect. The broader significance lies in the design principle: an abundant, inexpensive metal like cobalt, held in place by a robust nitrogen-rich polymer that needs no extra surface functionalization, can rival precious-metal systems while being recovered and reused with minimal loss. As regulators tighten limits on nitroaromatic pollutants in water, catalysts of this kind, fast at room temperature, stable across cycles, and built from earth-abundant elements, could become practical tools for cleaning up one of industry’s most stubborn classes of waste.

Subject of Research: Cobalt nanoparticles embedded in covalent triazine frameworks for catalytic reduction of nitroaromatic pollutants

Article Title: Cobalt nanoparticles embedded in covalent triazine frameworks (PD-CTF@Co): efficient catalyst for reduction of nitroaromatic compounds

Article References: Ahadi, N., & Bodaghifard, M. A. (2026). Cobalt nanoparticles embedded in covalent triazine frameworks (PD-CTF@Co): efficient catalyst for reduction of nitroaromatic compounds. Results in Chemistry, 30, Article 103878. https://doi.org/10.1016/j.rechem.2026.103878

Image Credits: AI Generated

DOI: 10.1016/j.rechem.2026.103878

Keywords: cobalt nanoparticles, covalent triazine frameworks, nitroaromatic compounds, 4-nitrophenol, heterogeneous catalysis, porous organic polymers, sodium borohydride, water purification, nanocatalyst, emerging pollutants, aromatic amines, catalyst recycling

The research was conducted within the Environmental influences on Child Health Outcomes program, a large federally funded initiative that pools data from multiple pregnancy and birth cohorts across the United States. The ECHO.CA.IL cohorts analyzed here represent geographically and demographically diverse populations, allowing researchers to examine exposure-outcome relationships with a breadth that single-site studies rarely achieve. Because developmental outcomes in infancy are shaped by an intricate web of genetic, social, and environmental factors, the scale and diversity of the cohort framework are essential for isolating signals that might otherwise be attributed to confounding influences.

Aromatic amines enter the human body through several well-characterized routes. They can migrate from colored textiles and food packaging into foodstuffs, particularly under heat, and they have been detected in tobacco smoke, diesel exhaust, hair dyes, and contaminated drinking water. Biomonitoring studies conducted over the past decade have found metabolites of these compounds in the urine of a large proportion of the general population, including pregnant women, which means that the developing fetus can be exposed through the placenta. Some aromatic amines, such as aniline and its derivatives, are classified or flagged as potential carcinogens in occupational settings, but their effects on the developing brain at everyday environmental levels have remained largely unexplored until recently.

To quantify prenatal exposure, the research team measured urinary concentrations of aromatic amine metabolites in samples collected from participants during pregnancy. Urinary biomarkers offer a window into recent integrated exposure and are considered one of the most practical tools for assessing contact with these chemicals in non-occupational settings. By combining laboratory measurements with questionnaire data on demographics, lifestyle, and environmental factors, the investigators were able to model the relationship between exposure levels and later infant outcomes while accounting for a range of potential confounders, including maternal education, household income, gestational age at birth, and infant sex.

Cognitive development in the infants was assessed using standardized developmental screening instruments administered during the first two years of life. These tools evaluate domains such as fine motor skills, expressive and receptive communication, problem-solving, and personal-social behavior. Rather than diagnosing disorders, such assessments generate continuous scores that capture subtle variation across a population. This approach is particularly valuable in environmental epidemiology, where the effects of low-level chemical exposure are expected to be modest shifts in the distribution of ability rather than dramatic impairments in individual children.

The central analytical question was whether higher concentrations of aromatic amine metabolites during pregnancy were associated with lower cognitive or developmental scores in infancy. Studies of this design must contend with the challenge that chemical exposures do not occur in isolation. Pregnant women exposed to aromatic amines are often simultaneously exposed to phthalates, bisphenols, flame retardants, and air pollutants, many of which share sources such as plastics, processed foods, and urban environments. The researchers therefore employed statistical adjustments and sensitivity analyses to test whether the observed associations could plausibly be attributed to aromatic amines themselves rather than to correlated co-exposures or residual confounding.

The broader significance of the work lies in what it reveals about the hidden chemistry of modern pregnancy. Aromatic amines have historically been studied almost exclusively in industrial hygiene contexts, where workers exposed to high concentrations faced well-documented risks of bladder cancer. The shift in focus toward population-level, low-dose exposure reflects a growing recognition that developmental windows of vulnerability, particularly the prenatal period, may be sensitive to chemical signals that produce no overt toxicity in adults. The fetal brain undergoes extraordinary waves of neuronal proliferation, migration, and synapse formation during gestation, and endocrine-active or neurotoxic compounds that perturb these processes can leave lasting developmental traces even at concentrations considered harmless by older toxicological benchmarks.

The findings also contribute to a rapidly expanding body of literature on the developmental origins of health and disease. This framework holds that conditions experienced in utero, ranging from maternal nutrition and stress to chemical exposures, program long-term trajectories of physical and cognitive health. Within this paradigm, even small shifts in population-level developmental scores can carry public health weight, because they indicate that a common environmental exposure is measurably interacting with the earliest stages of human neurodevelopment. When a chemical is detectable in the majority of pregnant women, as urinary biomonitoring suggests for several aromatic amines, a modest population-level effect translates into a meaningful burden at the societal scale.

For families, the practical question is what can be done to reduce exposure while the science matures. Aromatic amines can be released from intensely colored foods, dyed fabrics, rubber items, and some personal care products, and they are also present in secondhand smoke and vehicle exhaust. While individual avoidance is complicated by the ubiquity of these compounds, evidence-based strategies include minimizing contact with tobacco smoke, choosing fragrance-free and dye-minimal products where feasible, reducing the use of heavily dyed or rubberized items in food preparation, and supporting policies that restrict hazardous dye intermediates in consumer goods. Regulatory attention to aromatic amines has focused primarily on dye manufacturing and food contact materials in Europe, and studies of this kind strengthen the case for broader surveillance in North America.

The ECHO program’s cohort approach will continue to follow these children as they grow, offering the possibility of determining whether early-life associations with prenatal aromatic amines persist, attenuate, or amplify across childhood. Longitudinal extension is critical, because infant screening scores are imperfect predictors of later cognition and because developmental trajectories are shaped by compensatory environments after birth. In the meantime, the study adds an important and previously underappreciated class of chemicals to the list of prenatal exposures that clinicians, regulators, and researchers should monitor. As biomonitoring technology improves and cohort data accumulate, the scientific community moves closer to a complete map of the chemical landscape that accompanies every human pregnancy, and to evidence-based guidance for protecting the developing brain within it.

Subject of Research: Associations between prenatal exposure to aromatic amines and infant cognitive development in the ECHO.CA.IL cohorts

Article Title: Prenatal exposure to aromatic amines and associations with infant cognition in the ECHO.CA.IL cohorts

Article References: Eick, S. M., Ortlund, K., Padula, A. M., Kannan, K., Aguiar, A., Robinson, J. F., Morello-Frosch, R., Schantz, S. L., & Woodruff, T. J. (2026). Prenatal exposure to aromatic amines and associations with infant cognition in the ECHO.CA.IL cohorts. Journal of Exposure Science & Environmental Epidemiology. https://doi.org/10.1038/s41370-026-00905-3

Image Credits: AI Generated

DOI: 10.1038/s41370-026-00905-3

Keywords: aromatic amines, prenatal exposure, infant cognition, ECHO program, environmental epidemiology, neurodevelopment, biomonitoring, developmental toxicology, pregnancy, chemical exposure, public health, cohorts