The aim of this study was to investigate the factors that influence the sustainability of disposable baby diapers (nappies) using life cycle assessments (LCAs). Size 4 Pampers® Cruisers (North American name) and ActiveFit (European name) from 2007 are compared to new versions made in 2010 to determine if the design and materials changes intended to improve performance also lead to reductions in the most relevant environmental indicators.
Materials and methods
Cradle-to-grave LCAs, consistent with ISO 14040/14044 Standards, are conducted. The functional unit is “the number of diapers needed to collect excreta over a child’s diapering lifetime.” Input data come from P&G, suppliers, trade association reports, Franklin and ecoinvent databases, and Google. SimaPro 7 is used to model the LCA. Several life cycle impact assessments (LCIA) methods, sensitivity analyses, normalization to annual consumption, and Monte Carlo analysis are used to produce and check results.
Results and discussion
The consumption normalization identified that the diaper’s “environmental footprint” should include the IMPACT2002+ indicators: nonrenewable energy, global warming potential (GWP), respiratory effects from inorganics, total solid waste, and cumulative energy demand (CED). Other indicators are insignificant. Contribution analysis shows that the sourcing and production of diaper materials contribute most to the environmental indicators evaluated, accounting for ∼84% of all non-renewable energy uses and ∼64% of global warming potential. Diaper disposal is a small contributor (1–12%) to potential environmental impacts. Reductions observed for the 2010 US product are: CED—8%, solid waste—12%, non-renewable energy—1%, GWP500—4%, and respiratory inorganics—6%. For the European product, reductions are: CED—11%, solid waste—8%, non-renewable energy—3%, GWP500—5%, and respiratory inorganics—14%.
The new Pampers® diapers sold in the USA and Europe have a reduced environmental footprint versus the previous versions (2007). Significant reductions are achieved in non-renewable energy use and global warming potential, as well as other environmental indicators by optimizing the diaper design and the materials. Although some of the results are single digit reductions, Monte Carlo analysis indicates that there is a high probability that the differences are real. The use of multiple LCIA methods to compare products is helpful to confirm consistency of results. Normalizing the LCIA scores to annual consumption also helps prioritize which environmental indicators can be impactful and affected by changing a product.