Adult incontinence products are a larger and faster growing waste issue than disposable infant nappies (diapers) in Australia.

The environmental issues relating to disposable of infant nappies have received considerable attention. However, adult absorbent hygiene products (AHPs) receive less attention, despite having comparable or greater environmental impact. Here we quantify and compare current and future flows of continence related AHPs entering waste streams from both infant and adult populations. Importantly our study accounts for current waste management and landfilling practices across Australia and the environmental implications of AHP disposal. Absorbent hygiene product use from infants and adults was modelled from 2020 to 2030 for Australia, and it's predicted that AHP waste generated by adults will account for between 4 and 10 times that of infants by 2030 due to an aging population. Our results indicate that 50% of used AHPs end up in landfill with both leachate and biogas collection, the remainder going to landfills without biogas collection or without both leachate and biogas collection, based on the most recent national data set, which is over a decade old. The average composition of used absorbent hygiene product (including 60% urine and faeces by mass) is estimated to contain 20% non-biodegradable material, which may complicate the biodegradability of absorbent hygiene products in landfill. Without additional regulatory incentive, the current waste management practices in Australia are likely to continue, with absorbent hygiene products typically entering landfill as municipal solid waste, rather than industrial composting or recycling facilities. More accurate estimation of environmental implications from these disposal pathways requires further work including biodegradation experiments currently unavailable in the literature.