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Last Updated: Thursday, 19 May 2005, 14:53 GMT 15:53 UK
What really goes into a nappy?
A new report studies the impact on the environment of three types of nappy from manufacture to disposal. But what are they actually made from?

Baby in nappy, BBC
Eight million disposable nappies are discarded each day
Disposable nappies consist of a shaped pad covered in a soft liner and enclosed in a waterproof casing.

The liner or topsheet - made of the plastic polymer polypropylene - sits next to the baby's skin and protects against wetness. From this layer, fluids flow down through the pulp-based tissue layer and into the core.

The core contains fluff pulp and SAP, an absorbent polymer to draw in and contain the baby's urine and faeces.

Leakage from the nappy is minimised by a plastic bottom layer and the elastic barriers that hold the nappy around the child's waist. The nappy is thrown away after it is soiled.

More than eight million disposable nappies go into landfill sites every day in the UK alone. How fast any material breaks down is dependent on the individual management and construction of each landfill site.

70% - Core containing fluff pulp and absorbent material
10% - Polypropylene topsheet to protect against wetness
13% - Polyethylene backsheet to prevent leakage
7% - Other, including tapes, elastics and adhesives
The cellulose component of a disposable nappy originates from wood pulp, which usually comes from softwood trees such as spruce and pine. Although some of the wood pulp may come from sawmill residues.

In 2000, the Women's Environmental Network claimed to have found a chemical called tributyl tin which is known to disrupt sex hormones in nappies on sale in the UK.

The amounts were tiny, but the campaigners argued that no such chemicals should be in contact with a baby's skin.

Cotton picking

Reusable nappies are made of cloth which is either pre-shaped or folded, fitted with a throwaway liner and encased in a pair of waterproof baby pants that can be worn again.

The liner is thrown away but the cloth interior and pants can be machine washed and re-used over and over again.

Reusable nappies fall into three broad categories:

  • All-in-ones - shaped, fitted nappies with velcro or popper fastenings with a built-in waterproof cover.
  • Shaped nappies - similar to all-in-ones but without the waterproof cover. The covers are purchased separately and are known as wraps or pants.
  • Flat nappies (terry/wrap around/pre-fold) - require folding and a separate waterproof wrap/pant with fasteners.

The waterproof wraps and pants are generally manufactured from two plastic polymers: ethylene vinyl acetate (EVA) and polyvinyl chloride (PVC).

Liners in reusable nappies are made either of polypropylene or cellulose.

The flat terry nappy itself is made of cotton, a perennial crop. Mature cotton bolls are harvested mechanically and transported to a plant where the cotton fibre is separated and baled.

Bales of cotton are then transported to textile manufacturers or yarn spinning plants, where they are opened, the cotton fibre is disentangled and spun into yarn.

The yarn is subsequently woven into terry towelling, cut and stitched.

Trial puts 'real' nappies to test
22 Apr 05 |  Somerset
Nappy recycling plant is planned
06 Oct 04 |  Nottinghamshire
Nappy 'link to infertility'
25 Sep 00 |  Health

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