For millions of people around the world, tampons and menstrual pads are a monthly staple products used for days at a time, every month, for decades. But a growing body of research is raising questions about what exactly is inside those products, and whether the chemicals detected in them could pose a meaningful risk to the people who use them most.
Scientists have found small amounts of toxic heavy metals, endocrine-disrupting compounds and other potentially hazardous substances in a range of menstrual products. The health implications remain uncertain, but researchers say the findings are significant enough to warrant serious attention and better federal oversight.
What researchers have found
In 2024, environmental epidemiologist Jenni Shearston co-authored the first study to detect metals in tampons. The findings were notable: lead was present in all 30 tampons tested. Arsenic was also detected. A companion review of roughly two dozen existing studies found that menstrual products frequently contain chemicals associated with hormone disruption, reproductive harm and other health concerns.
The concentrations detected were generally low, making the direct health impact difficult to determine. But researchers emphasize that low concentration does not automatically mean low risk particularly when exposure is repeated, prolonged and involves tissue that is especially efficient at absorbing substances.
Tampons are used internally, surrounded by the vaginal mucous membrane for up to eight hours at a time. That membrane is permeable and absorbs certain chemicals readily, which is precisely why scientists say this area of research deserves more resources and urgency than it has historically received.
How these substances get into period products
Tampons have been manufactured primarily from cotton, rayon or a blend of the two since the first modern version was patented in the U.S. in 1931. The pathways through which chemicals enter those materials vary widely.
Heavy metals such as lead and arsenic occur naturally in soil and can be absorbed by cotton plants during growth. Other substances, such as zinc, are added intentionally to inhibit bacterial growth. Phthalates synthetic chemicals commonly used in plastics manufacturing can migrate into products from plastic packaging or be introduced through fragrance formulations. Volatile organic compounds may be incorporated through adhesives or scented components.
The result is a product category where chemical presence is common, the sources are varied and the regulatory framework has not been designed to address the full scope of what researchers are now finding.
Where federal regulations fall short
The U.S. Food and Drug Administration classifies tampons and menstrual cups as Class II medical devices, carrying moderate risk designation. Unscented pads fall into the lower-risk Class I category. Within those classifications, guidance around chemical content is limited.
For tampons and pads, the FDA recommends but does not require that products be free of two specific dioxin compounds and residues from pesticides and herbicides. Dioxins are a by-product of the chlorine bleaching process used to whiten cotton fiber and are linked to cancer and endocrine disruption. Non-chlorine bleaching methods can significantly reduce their formation, though no federal rule mandates that manufacturers make the switch.
The most aggressive regulatory action around tampon safety in U.S. history came not from chemical concerns but from an outbreak of toxic shock syndrome in the 1970s and 1980s. The condition, caused by a toxin released by the bacteria Staphylococcus aureus in the presence of inserted menstrual products, led to at least 52 documented cases and seven deaths over eight months. A highly absorbent tampon called Rely was pulled from the market, and the FDA subsequently standardized tampon absorbency levels which is why products today range from light to ultra, allowing users to select the lowest effective level and reduce bacterial risk.
The broader challenge of chemical exposure
One of the central difficulties in understanding what menstrual product chemicals mean for human health is that no one is exposed to a single substance in isolation. Toxicologist Linda Birnbaum, former director of the National Institute of Environmental Health Sciences, has described the modern human condition as living in a soup of chemicals a constant, overlapping mix of exposures that makes it difficult to isolate the effect of any one compound.
That complexity, however, does not mean individual sources of exposure should be dismissed. Research on vaginal douching offers a relevant precedent. A 2015 study found that people who douche had measurably higher levels of monoethyl phthalate in their urine, a chemical linked to reduced fertility and increased pregnancy complications. The American College of Obstetricians and Gynecologists recommends against douching for this reason. A 2025 study further estimated that volatile organic compounds can be absorbed through the vaginal mucosa from menstrual products.
The science is still developing, and researchers are working to establish what concentrations of metals and other chemicals actually leach out of tampons during use. But for a product used by roughly half the global population, repeatedly, over the course of their reproductive lives, advocates argue the burden of proof should be higher and the research investment much greater than it has been so far.
