Seaweed-Enhanced Menstrual Cup Aims to Cut Waste, Improve Safety and Enable Health Monitoring

Seaweed tablet inside reusable cup could reduce waste and improve menstrual care

Researchers at McMaster University report a novel menstrual-cup system that uses a dissolvable, seaweed-derived tablet to absorb menstrual blood. The team says the tablet can reduce spills, help repel bacteria and lessen the need for frequent boiling, while enabling a reusable cup to remain effective for several years—potentially cutting reliance on single-use products.

Why this matters

Global waste from menstrual products is substantial: the World Health Organization estimates more than 200,000 metric tons of menstrual waste are discarded annually. In North America alone, nearly 20 billion sanitary pads, tampons and applicators end up in landfills each year, according to reporting cited by the researchers.

Single-use menstrual items are highly plastic: Days for Girls estimates that such products are roughly 93% plastic. Manufacturing disposables consumes fossil fuels and contributes to greenhouse gas emissions. When these items are discarded they can take hundreds of years to break down, create persistent microplastics and produce methane as they decompose. Separate research from Indiana University and the University of Notre Dame has also raised concerns about potential exposure to harmful chemicals from some disposable products.

The innovation

Published in ACS Applied Materials & Interfaces, the McMaster study describes a dissolvable tablet made from seaweed that is placed inside a reusable menstrual cup. The tablet quickly absorbs menstrual fluid, reducing the risk of spills and improving hygiene by helping to repel bacteria. According to the researchers, a cup fitted with the tablet could remain effective for several years, lowering the volume of single-use waste and offering cost savings for users.

"This project opened my eyes to how urgently innovation is needed in menstrual care," said Zeinab Hosseinidoust, associate professor of biomedical and chemical engineering at McMaster and co-lead on the study.

The team builds on the existing Bfree Cup technology and suggests this approach could broaden adoption, reduce period poverty and lead to further advances—such as integrating sensors to detect infections or other health signals.

"This could be a new form of wearable technology that might prove even more valuable than a smartwatch," said Tohid Didar, associate professor of mechanical and bioengineering at McMaster and co-lead of the research. "We have mainly been reactive in terms of women's health. This gives an opportunity to be proactive."

Access and next steps

Cost and access remain major barriers: the researchers note that about two-thirds of women globally cannot consistently afford the menstrual products they need. A durable, lower-cost reusable option could help reduce that burden. The team emphasizes that additional testing, real-world trials, durability and safety evaluations, and regulatory review will be needed before broad deployment.

Overall, the study highlights a promising route toward more sustainable, affordable and potentially diagnostic menstrual care—while underscoring the need for further research and inclusive implementation strategies.

Reporting on the work was cited from Interesting Engineering and the original study in ACS Applied Materials & Interfaces.