Earlier toilet training and new recycling technologies are among expert-backed solutions to reduce the environmental impact of disposable nappies and other hygiene products, described in a new study led by UCL researchers.
The paper, published in Nature Sustainability, sets out a roadmap for changing how absorbent hygiene products (AHPs), which include nappies, incontinence products and period products, are designed, used and disposed of.
AHPs account for an estimated 160–200 million tonnes of waste each year globally, with the vast majority sent to landfill or incineration. In regions without adequate waste collection, used nappies are often dumped or burned, contributing to plastic pollution, contaminated water and the spread of disease.
The research team identified three system interventions that they expect will radically reduce the environmental impact of AHPs. They say behaviour change around toilet training, and more use of reusable products can reduce product use; new and scalable recycling technologies will promote a more circular system; developing completely compostable products can divert products from landfill and incineration to produce compost or biogas.
Dr Elze Porte, Senior Research Fellow at UCL Mechanical Engineering and lead author of the study, said: "More than 300,000 nappies are thrown away globally, every minute. In the UK alone, around 14 million people experience incontinence, many of whom use disposable incontinence products. This makes absorbent hygiene products a major, yet largely unrecognised, contributor to the plastic waste crisis.
"These products are essential for health, dignity and caregiving, but their environmental impact has largely gone under the radar. What our research shows is that this is not a problem with a single solution. It requires coordinated changes across behaviour, technology, materials and policy."
The first intervention recommended by the authors is around reduce and reuse, encouraging earlier toilet training and greater uptake of reusable nappies. They note that earlier toilet training may also benefit children's bladder and bowel health.
The study recognises that changes to nappy use carry challenges, because of a lack of guidance, time pressures on caregivers, and the perceived convenience of disposable products. It calls for better support for families, including clearer guidance from healthcare providers and changes to workplace and childcare systems that make lower-waste practices more feasible.
Second, more emphasis on technologies for recycling AHPs is needed because of disposable nappies' complex mix of plastics, fibres and super-absorbent materials, combined with contamination from human waste and medicines. While a small number of recycling technologies exist, most recover only part of the materials.
The researchers recommend developing recycling methods that can recover all nappy materials on a large scale, as well as better decontamination technologies to remove pathogens and medicine residues from used products.
The third potential solution is to develop nappies made entirely from materials that can safely biodegrade in industrial composting or anaerobic digestion systems. Currently available products marketed as biodegradable are not fully compostable, and key technical challenges remain, including maintaining dryness, and ensuring that contaminants are safely broken down.
The researchers point out that, to make this feasible in the UK, regulatory and economic barriers such as restrictions on the use of compost containing human waste must be addressed before this approach can be widely adopted.
The paper builds on the Big Toilet Project , run by the UCL Plastic Waste Innovation Hub, which examines why children are being toilet trained later and how this affects nappy use.
In many countries, the average toilet training age of children has increased. In the UK this has risen by 32%, from two years and four months on average in the 1950s to just over three years in the 2000s, meaning that the number of disposable nappies per child has increased.
Professor Mark Miodownik (UCL Mechanical Engineering), senior author of the study and lead researcher on the Big Toilet Project, said: "Our earlier work has highlighted how changing social norms and caregiving pressures are contributing to increased nappy use. This new paper takes that further, showing how those behavioural trends intersect with materials and waste systems to create a global environmental challenge and, importantly, what we can do about it."
The authors stress that no single solution will work everywhere. In high-income countries, improving recycling and reducing use may be most effective, while in lower-income regions, where waste infrastructure is not as well developed, locally appropriate composting or disposal solutions may be needed.
They also highlight the importance of ensuring that any changes remain affordable, particularly for people who are vulnerable, as hygiene products are essential rather than optional.
