A 2026 University of Otago study found that 8 of 18 tampon brands tested (44%) released low levels of oestrogen-like chemicals when soaked in a lab extraction process, with positive results in both organic and synthetic products. The chemicals were detected in a cell-based bioassay, not measured inside the human body, so the study cannot yet tell us whether this exposure affects health.
Key takeaways
- Researchers tested 18 tampon products (13 brands, various absorbencies and countries of origin) using a human breast cancer cell line engineered to light up when exposed to oestrogen-like compounds.
- 8 of the 18 products (44%) triggered a detectable response, meaning chemicals had leached out of the tampon material during soaking.
- Both organic and synthetic tampons were affected. Being labelled organic did not guarantee a negative result, and several fully synthetic brands also tested negative.
- Chemical analysis pointed to plasticisers, surfactants and fragrance agents (including phthalates and alkylphenols) as the likely source of the activity in the affected brands.
- The study did not measure whether these chemicals are absorbed into the body during real-world tampon use, at what dose or with what health effect. The researchers are explicit that this cannot be concluded from the current data.
- 10 out of 18 products showed no detectable estrogenic activity, which the study's senior author says proves lower-chemical formulations are achievable industry-wide.
- The researchers did not disclose the names of the tampon brands tested; instead, they focused on the overall findings rather than individual manufacturers.
What the study actually did
The research, led by Professor Alison Heather's team at the University of Otago (in collaboration with biotech company InsituGen), tested 18 tampon products purchased from supermarkets and online retailers in New Zealand, Australia, the USA, Israel, Slovenia and elsewhere in Europe.
Each tampon was cut into portions, soaked in a water/ethanol solution for 4 hours to mimic typical wear time, then processed to extract any chemicals that had leached into the liquid. That extract was applied to T47D-KBluc cells, a laboratory cell line that lights up when its oestrogen receptors are activated. If the cells responded, it indicated the presence of chemicals capable of mimicking oestrogen.
This method measures the combined, real-world effect of whatever mixture of chemicals is present, rather than testing for one chemical at a time. It's a widely used approach for detecting endocrine activity in complex products, but it is still an in vitro (lab dish) test, not a measure of what happens in the human body.
What was found, by tampon type
| Tampon type (as labelled) | Number tested | Showed detectable oestrogen-like activity |
|---|---|---|
| Organic or cotton-labelled | 12 | 4 |
| Synthetic or rayon-blend | 6 | 4 |
The researchers were clear that estrogenic activity turned up in both categories, and that being certified organic did not automatically protect a product. Because each subgroup here is small, these counts should be read as a snapshot from this specific set of products rather than a verdict on "organic" or "synthetic" as categories.
Chemical analysis comparing one affected and one unaffected brand identified a broader range of plasticisers, surfactants and fragrance compounds, including known or suspected endocrine-disrupting chemicals such as phthalates and alkylphenols, in the affected product at much higher concentrations. These are typically added during manufacturing for flexibility, fibre processing, scent or comfort rather than being inherent to raw cotton or rayon.
What this doesn't tell us
It's worth being precise about the limits of this research, because headlines can run ahead of the data:
- The study measured chemical leaching into a lab extract, not absorption through vaginal tissue during actual use.
- It did not measure blood or tissue levels of any chemical in a real person.
- It did not test for, or find, any link between tampon use and a hormonal condition, cancer or fertility outcome. The researchers describe the detected activity as low and say further research is needed before any health conclusions can be drawn.
- It's a single study using one type of cell assay. Replication and follow-up research (including studies that measure actual absorption) will be needed to understand real-world significance.
The encouraging part of the findings
The researchers highlight that several brands, both organic and synthetic, showed no detectable oestrogenic activity at all. The study's senior author has said this demonstrates that low-chemical, non-estrogenic formulations are achievable across the industry, and has called for menstrual product safety testing to include endocrine-related assessments alongside the existing focus on absorbency, irritation and infection risk.
Why some people look at reusable options
Menstrual cups, discs, reusable sea sponge tampons and cloth pads are generally made from a small number of relatively simple materials, such as medical-grade silicone, natural rubber or certified textiles, compared with the more complex mix of processing agents that can go into disposable products. Reusable products were not tested in this study, so no direct comparison can be made based on this research. But for people who want more visibility into what a product is made from, some find that simpler material lists make it easier to ask informed questions of manufacturers.
The bottom line
This study is a useful, credible early step in applying modern endocrine-safety testing to menstrual products, something that's historically been part of the standard safety checks for tampons. It shows that leaching of low-level oestrogen-like chemicals occurred in nearly half of the products tested, in both organic and synthetic brands and that some brands avoided this entirely. It does not show that tampons are unsafe or that using them causes any health condition. The most useful takeaway for consumers right now is that greater ingredient transparency and expanded safety testing standards are what the researchers are calling for.
Frequently asked questions
Does this study prove tampons are unsafe? No. The researchers are explicit that detecting low-level oestrogen-like activity in a lab test does not mean tampons cause harm. It shows some brands release detectable chemicals under lab conditions, and flags a research gap worth closing, not a proven health risk.
Were organic tampons affected? Yes, some were. Of the 12 organic or cotton-labelled products tested, 4 showed detectable activity. The researchers note this suggests manufacturing additives, rather than the raw cotton itself, are the more likely source.
Which chemicals were responsible? Chemical analysis pointed to plasticisers (including phthalates), surfactants and fragrance agents as the most likely contributors, based on a comparison between one affected and one unaffected brand.
Does the study say how much of these chemicals gets into the body? No. The study measured what leached into a lab extract, not what is absorbed through the body during actual tampon use. That question remains open and would need separate research to answer.
Should I stop using tampons because of this? That's a personal decision, and this study alone isn't a reason to stop if tampons work well for you. If you're curious about alternatives, options like menstrual cups, discs or reusable cloth pads use a smaller number of raw materials, though they haven't been tested in this particular study.
Where can I read the original research? The peer-reviewed paper, Estrogenic Activity in Tampon Products by Sutherland, Manodara, Gillon, Stevens, Kauff and Heather, is published in the Journal of the Endocrine Society (2026).
This article is for general information and is not medical advice. If you have concerns about your menstrual or hormonal health, please speak with your GP or a qualified healthcare professional.
References
- Sutherland ES, Manodara G, Gillon A, Stevens KL, Kauff A, Heather AK. Estrogenic Activity in Tampon Products. Journal of the Endocrine Society. 2026;10:bvag094.
- University of Otago newsroom: "Tampons tested for hormone disrupting chemicals"
- Otago Daily Times: "Study finds half of tampons tested contained hormone-interfering chemicals"
- Sexual Wellbeing Aotearoa: "We need more research into tampons – and all period products"
https://periodshop.com.au
