The “breathable” outer layer is typically made of polyethylene, a thermoplastic. Inside that you’ll find a blend of cellulose pulp (in most brands, wood pulp is bleached with chlorine) and absorbent polymers. You may also find Velcro or adhesive tabs, chemical “wetness indicators” that change colors to show when the diaper is wet, and scents or lotions.
Check out this website for more detail on how a disposable diaper is made.
Most diaper companies do not use recycled materials to make their diapers, so the wood pulp is derived from freshly-harvested trees. The polymers that keep disposables dry on the outside and absorbent on the inside are petroleum products, but in the future manufacturers could try making these layers out of recycled milk jugs. (I am not a chemical engineer, so someone correct me if this idea isn’t feasible.) Even Seventh Generation, who makes a chlorine-free disposable diaper, does not use any recycled materials for the poly-wraps on their diapers and training pants. Their website says they plan to “upgrade this to 50% recycled content” in 2008. We’re not sure if they accomplished this goal or not!
These superabsorbent polymers come out of a disposable diaper in a science experiment.
Now, it’s great that Seventh Generation avoids using chlorine bleach, but they are no more biodegradable than other disposables. Their diapers are made from the following ingredients, according to their website: chlorine-free wood pulp fluff, sodium polyacrylate (also known as SAP or absorbent gel), polyolefin nonwoven fabric, adhesives, polyolefin film, synthetic rubber elastic strands. For a biodegradable disposable, look into gDiapers. Their diapers are biodegradable and compostable, although they still use absorbent gel and tree-farmed wood pulp.
While it’s no secret that we love our cloth diapers here on the Green Baby Guide, we realize that disposables are here to stay. Our hope is that manufacturers–especially eco-conscious ones like Seventh Generation–keep working on creating disposable diapers using more recycled content and fewer non-biodegradable materials.