Reusables only
reduce waste
if people keep
using them

The environmental case for reusable menstrual products is strong and well evidenced. The arithmetic most programmes use to claim it is not.

What the life-cycle evidence actually shows

Comparative life-cycle assessment is unusually clear on this category. Across eight environmental impact indicators and three country contexts, reusable products — pads, underwear and cups — score lower than disposable pads and tampons on every impact except water use. The menstrual cup has the lowest impact score across all indicators, with impacts over one year amounting to less than 1.5% of the disposable equivalents.12

The disposal side is equally well established: over 80% of menstrual products in Europe and the USA end up in landfill, where plastic components can take up to 500 years to break down.1 In contexts with no formal waste collection at all — which describes much of where we work — they are burned or buried at the household instead.

So far, so supportive. Now the finding that programme designers tend to skip past.

Reusable pads produced abroad and shipped by airfreight had the highest environmental impacts of any option assessed — worse than the single-use products they replace.

That is not a marginal caveat.1 It means the environmental case for a reusable product is conditional on how it is made and moved, not intrinsic to the product category. A programme that imports reusable pads by air and reports waste displaced has, on the available evidence, potentially made the environmental position worse while reporting an improvement.

The modelling error

Here is how a displacement figure is usually built. Take the product's rated lifespan — say two years. Take average disposable consumption over the same period. Subtract. Multiply by participants. Report the total as waste displaced.

Every step is arithmetically correct and the result is still unreliable, because the first step assumes the product remains in use for its rated lifespan. Rated lifespan is a property of the textile. Continued use is a property of the household.

What continued use actually depends on

• Water availability. A reusable pad has to be washed. Where water is scarce, seasonal, or rationed by distance, washing competes with drinking, cooking and other laundry — and loses.
• Private drying space. Pads must dry fully, ideally in sunlight, to be safe to reuse. In a household with no private outdoor space, or where drying a menstrual product in view is not acceptable, the product gets dried badly or abandoned.
• Household acceptance. The user is frequently not the decision-maker about what is washed, dried or kept in the home.
• Product condition. Textiles degrade faster under hand-washing, hard water and sun exposure than under the laboratory conditions that produce a rated lifespan.

None of these are addressed by distributing a better product. All of them determine whether the waste figure is real.

The Pakistan case, specifically

These are not hypothetical constraints. In the largest study of menstrual hygiene practice in rural Pakistan — 25,305 women in Matiari district, Sindh — 61.9% were using old cloth and 12.6% were using nothing at all. Poor handwashing practice was independently associated with inadequate menstrual hygiene management, at odds of 3.12.3

That association is the whole argument in one statistic. Where water and handwashing are constrained, menstrual hygiene is constrained — and a reusable product introduced into that setting inherits the constraint rather than solving it.

How we model it instead

We do not model waste displacement on rated lifespan. We model it on observed reuse at follow-up, which requires actually going back and asking — the step that makes the method more expensive and the number worth having.

• Follow-up at a fixed interval after distribution, on the same participants, asking whether the product is still in use, how often, and if not, why not.
• Observed reuse rate replaces rated lifespan in the displacement calculation. If 60% of participants are still using the product at follow-up, the model uses 60% — not the manufacturer's figure.
• Non-use reasons are coded and published, because they are the most useful output of the whole exercise. Water, drying space, household objection and product failure imply completely different design responses.
• Transport and manufacture are stated, in line with the LCA evidence. Local manufacture is preferred wherever it is available at an acceptable standard — not primarily for cost or livelihoods, though both matter, but because airfreighted reusables can invert the environmental case entirely.
• The model is published with its sensitivities, so a reader can see what would have to be true for the figure to be wrong.

What this costs, and why we do it anyway

Modelling on observed reuse produces smaller numbers than modelling on rated lifespan. Always. That is an uncomfortable property for anyone whose reporting incentive points towards a larger figure.

It is also the only version that survives scrutiny — and as sustainability disclosure moves towards assurance, a modelled figure with no published method and no sensitivity analysis stops being an asset and becomes a restatement risk.

The smaller number has one further advantage: it is actionable. A displacement figure derived from rated lifespan tells you nothing you did not already know. A figure derived from observed reuse tells you that 40% of participants stopped, and coded reasons tell you whether the fix is a water point, a drying solution, a conversation with mothers, or a better product.