The following information is from the Huggies website for the United Kingdom. Apparently the Europeans are more concerned about these things than us trusting Americans!
What are the ingredients in Huggies® nappies?
The inside absorbent padding on Huggies® nappies is made of wood cellulose fibre, a fluffy paper-like material, and a super-absorbent material called polyacrylate. Other materials used include polypropylene, polyester, and polyethylene. These are all synthetic materials designed to enhance the fit of the nappy and to help stop leaks. The elastic strands in all Huggies nappies are made of synthetic rubber to provide a snug but gentle fit for baby. In addition, Huggies® nappies feature an all-over breathable outer cover.