Infants Carry Significantly Higher Microplastic Levels Than Adults, Study Finds

Researchers testing fecal samples from newborns, one-year-olds, and adults have found that the youngest children carry microplastics at levels roughly ten times higher than grown-ups—and traces of plastic show up even in the first bowel movements of newborns, suggesting exposure begins before birth.

The pilot study, published in Environmental Science & Technology Letters, examined samples from three newborns, six infants around one year old, and ten adults, screening specifically for two common types of plastic while deliberately excluding polypropylene, which could contaminate results from diaper material. Every adult and infant tested positive for one or both plastics. But the gap in concentration was striking: the one-year-olds carried roughly ten times as much plastic as the adults, on average. Even more unsettling, some of the newborns showed plastic in their systems, indicating that children are absorbing these materials in the womb—a finding that aligns with earlier research detecting plastics in placental tissue.

Microplastics are any plastic fragments smaller than five millimeters. They have become ubiquitous in the environment, turning up in oceans, soil, air, and now routinely in human bodies. The concern isn't simply the plastic itself but the chemicals bound up in it. Plastics leach endocrine-disrupting compounds, or EDCs, which mimic the hormones that regulate sleep, fertility, and other vital functions. Some research has linked these chemicals to infertility, metabolic disorders including diabetes, and certain cancers. The worry deepens when considering that hormones are essential to development—puberty, growth, and neurological maturation all depend on them.

Kurunthachalam Kannan, an environmental health scientist at New York University School of Medicine and one of the study's authors, told Wired that modern life exposes infants to countless substances whose effects remain unknown. The sources of exposure are not yet fully mapped. Parents might assume the main culprits are obvious—plastic toys, milk bottles, pacifiers that children mouth constantly. But Deonie Allen, a microplastic researcher at the University of Strathclyde who was not involved in the work, cautioned that the picture is likely more complex. "We need to look at everything a child is exposed to, not just their bottles and toys," she said, describing the study's findings as "very worrying."

The research is framed as a pilot study—an early probe meant to determine whether deeper investigation is warranted. The sample sizes are small, and the results are not yet conclusive. Many questions remain about exactly how much harm microplastics and their chemical cargo inflict, and at what exposure levels damage occurs. Yet the timing of exposure appears critical. If these findings hold up under scrutiny, they suggest that young children face a particular vulnerability during windows when their bodies are still forming.

Because plastics have become woven into nearly every aspect of modern life—from packaging to textiles to building materials—individual choices offer limited protection. Scientists are increasingly calling for systemic intervention. Last year, the Endocrine Society and partner organizations issued a major report designating plastics a global health threat to both wildlife and human populations. The implication is clear: reducing microplastic exposure will require action at the industry and policy level, not just at the household level. For now, the question of what these elevated levels mean for children's long-term health remains open.