The average child born in the UK in the 1950s was toilet trained by the age of two years and four months. Five decades later, the average child wouldn’t reach that milestone until after their third birthday.
Those statistics are more than just a curious reflection of changing parenting practices. They also shed light on the growing plastic waste crisis. Later toilet training means more used diapers, and since the diaper market also shifted from mostly cloth to mostly disposable over the same decades, that all adds up to a lot more diapers being tossed in the trash.
Today, more than 300,000 diapers are thrown away every minute around the globe. In wealthy countries, the vast majority of disposable diapers and other absorbent hygiene products such as incontinence products and menstrual supplies wind up in a landfill or incinerator. In parts of the world that lack good waste collection systems, diapers are often dumped or burned, resulting in plastic pollution, contaminated water, and the risk of disease.
Absorbent hygiene product waste amounts to somewhere between 160 and 200 million metric tons each year and makes up nearly one-tenth of municipal solid waste by weight globally, according to a new paper in Nature Sustainability. “With a growing and ageing population this problem is only getting worse, so it is important we act now to reduce the waste, and find more sustainable solutions for the waste that is inevitable,” says study team member Elze Porte, a materials sustainability researcher at University College London.
Porte and her collaborator, UCL materials scientist Mark Miodownik, spent two and a half years (if their study were a child born in the 1950s, it would be toilet trained by now) talking with manufacturers of cloth and disposable diapers, government agencies, waste collection and processing companies, and caregiving and healthcare professional organizations. They even visited a factory and a diaper recycling facility.
The result is three broad strategies for making absorbent hygiene products more sustainable. (Their strategies focus on diapers but are more broadly applicable, they say.) One is to reduce the use of disposable hygiene products. That could be accomplished by switching to reusable diapers or earlier toilet training – or, more precisely, reversing the trend towards later toilet training.
Changes to workplace and childcare systems are needed to make this more feasible for parents, the researchers say. But earlier toilet training can also be better for children’s bladder and bowel health. “For us, this was interesting to learn, because it means that reducing diaper waste by bringing back down the toilet training age can save money for families, support children in their development, and is better for the environment,” Porte says. “It is rare to find such a win-win-win solution.”
A second strategy is developing technologies to recycle absorbent hygiene products. This is challenging because disposable diapers are a complex mix of materials: different kinds of plastics, fibers, superabsorbent gels. So there needs to be a way to collect used diapers separately from other municipal waste, then separate the different materials and then recycle each one.
But recycling diapers isn’t as pie-in-the-sky as it might first sound. There are several diaper recycling facilities already operating in multiple countries, although they generally only recycle part of the diaper and often result in downcycling of materials.
The final strategy is developing fully compostable absorbent hygiene products. The challenge here is making products that will break down in an industrial composter, but not when exposed to the similarly warm, moist environment of the human body.
A separate group of researchers have developed a biodegradable material based on cellulose and citric acid that could replace the fossil-fuel based absorbent gels used in conventional disposable diapers.
Both recycling and composting will require new technologies to remove pathogens and medicine residues from used hygiene products. Some jurisdictions restrict composting of human waste, so regulatory changes may also be necessary. In the meantime, “We are now doing more work on understanding worldwide toilet training practices in the Big Toilet Project,” Porte reports. “We ask parents and carers around the globe to help us by sharing their toilet training journey, helping us to gain insights into how and when they toilet train their children, understand best practices and identify where support is lacking.”
Source: Porte E. and M. Miodownik. “Research priorities for addressing global absorbent hygiene product waste.” Nature Sustainability 2026.
Image: ©Anthropocene Magazine (baby photo: AndriyPorokhnenko/
