A baby’s first teeth may become an unexpected archive of life inside a neonatal intensive care unit. A new study from the Developmental Impact of NICU Exposures, or DINE, project reports that shed teeth can be used to investigate metal exposure in infants born prematurely, offering researchers a rare way to reconstruct chemical conditions during one of the most medically intensive periods of early development. The work, published in the Journal of Exposure Science & Environmental Epidemiology, focuses on a question that has long challenged scientists: how can exposure to metals be measured retrospectively in newborns who may have spent weeks or months receiving complex hospital care?
Premature infants are especially important in this investigation because their organs and biological systems are still developing when they enter the world. Many require respiratory support, intravenous nutrition, medication, blood products, monitoring devices and other interventions that are essential for survival. At the same time, they may be more vulnerable to environmental contaminants because the liver, kidneys, lungs and nervous system have not reached full maturity. Metals are not a single category of hazard. Some, such as iron, zinc and manganese, are necessary for normal biological function but can become harmful at excessive concentrations. Others, including lead and cadmium, have no known beneficial role in the body and may affect neurological, immune or developmental processes even at relatively low levels.
The DINE study uses shed teeth as a biological record of exposure. Teeth begin forming before birth and continue developing through infancy, creating layers of mineralized tissue that preserve chemical information from different stages of early life. As a tooth grows, elements circulating in the blood can become incorporated into dentin and enamel. Once deposited, those layers can remain stable for years. Unlike a blood or urine sample, which generally reflects recent exposure, a tooth may provide a chronological record of exposure during fetal development, the newborn period and later infancy. This makes teeth particularly valuable for studying preterm infants, whose early medical histories can be difficult to reconstruct using conventional biological samples.
The scientific method behind this approach is known as tooth-matrix biomonitoring. Researchers collect naturally shed baby teeth, clean them to remove external contamination and analyze their elemental composition using highly sensitive laboratory instruments. Techniques such as laser-ablation inductively coupled plasma mass spectrometry can measure tiny concentrations of metals while also determining their location along the growth axis of the tooth. In practical terms, the instrument can examine one microscopic section after another, allowing investigators to distinguish chemical signals associated with different periods of development. The resulting pattern may then be compared with medical records, including gestational age, length of NICU stay, respiratory treatment, nutrition, medications and other clinical interventions.
The study is significant because exposure assessment in neonatal medicine has traditionally depended on environmental measurements or samples taken at a limited number of time points. Air, water, medical devices and hospital materials can all contribute to a complicated exposure environment, but measuring the presence of a metal in a room or piece of equipment does not necessarily reveal how much reached an infant’s body. Blood and urine testing, meanwhile, can be difficult to perform repeatedly in medically fragile newborns and may reflect only a narrow window of time. Shed teeth offer a non-invasive alternative after the fact. By linking the chemical record in teeth to detailed hospital histories, researchers can begin to ask whether particular treatments, devices or patterns of care are associated with higher or lower metal burdens.
The DINE findings also highlight the importance of distinguishing correlation from causation. If a tooth contains a higher concentration of a metal during a period corresponding to intensive treatment, that does not automatically prove the treatment was the source. Premature infants may experience multiple exposures at once, including those originating before birth, from nutrition, medications, household environments or medical equipment. Their metabolism can also differ from that of full-term infants, changing how metals are absorbed, distributed and eliminated. For this reason, the study’s value lies not simply in identifying metals, but in establishing a framework that combines tooth chemistry with exposure histories, clinical information and statistical methods capable of handling several overlapping factors.
The research could eventually help answer questions with direct implications for neonatal safety. NICU care has transformed survival for very premature babies, and the goal is not to question interventions that save lives. Instead, exposure science can help refine those interventions by identifying materials or procedures that might be modified without compromising treatment. If a recurring chemical pattern is linked to a particular device, source of nutrition or medication pathway, hospitals could investigate safer alternatives, improve monitoring or introduce additional safeguards. The same approach could also reveal protective factors, such as nutritional conditions that support healthy mineral balance or clinical practices associated with lower exposure.
For parents and clinicians, the use of shed teeth may provide a new bridge between early medical experiences and long-term health research. Prematurity has been associated with later differences in learning, behavior, growth and respiratory health, but the biological pathways are often difficult to isolate. Metal exposure is only one possible contributor among many, and the DINE study does not establish that metals cause specific developmental outcomes. It does, however, create a tool for testing those possibilities more rigorously. Future studies may compare tooth-based exposure signatures with neurodevelopmental assessments, growth measurements and health records, while also examining whether the timing, rather than simply the total amount, of exposure is most important.
The broader message is that the smallest biological materials can preserve some of the most important chapters of human development. A tooth that appears years after a child leaves the hospital may contain a microscopic timeline reaching back to the NICU and even before birth. By turning that timeline into data, the DINE study opens a new route for investigating how modern medical care and environmental chemistry intersect at the beginning of life. The work is not a verdict on neonatal treatment, nor a reason for alarm, but a reminder that survival and safety must be studied together. As researchers improve the accuracy of tooth-based testing and expand the number of children followed over time, these tiny records could help make intensive care not only more effective, but also more precisely tailored to the developing body.
Subject of Research: Metal exposures in premature infants measured through shed teeth and associated with neonatal intensive care experiences.
Article Title: Assessing preterm infant metal exposures in shed teeth: findings from the Developmental Impact of NICU Exposures (DINE) study
Article References: Lieberman-Cribbin, W., Spear, E., Gennings, C. et al. Assessing preterm infant metal exposures in shed teeth: findings from the Developmental Impact of NICU Exposures (DINE) study. J Expo Sci Environ Epidemiol (2026). https://doi.org/10.1038/s41370-026-00959-3
Image Credits: AI Generated
DOI: 10.1038/s41370-026-00959-3
Keywords: premature infants, neonatal intensive care unit, NICU exposures, metal exposure, shed teeth, tooth biomonitoring, developmental epidemiology, environmental health, preterm birth, DINE study
Tags: biological vulnerability of preterm infants to metal contaminantsdevelopmental impact of metal exposure in preemiesenvironmental health in neonatal intensive care unitsinnovative techniques in environmental epidemiologylong-term effects of early metal exposure on child developmentmetal toxicity risk in premature infantsneonatal intensive care unit environmental contaminantsnon-invasive methods for assessing neonatal chemical exposurePreterm infant metal exposure analysisretrospective chemical exposure assessment in newbornsshed teeth as biomarkers of early metal exposureuse of dental tissues to study environmental toxins
