Despite their name, disposable diapers are difficult to break down in a landfill; studies suggest they may take centuries to rot away. The reason they are so persistent is that the main ingredient of disposable diapers is cellulose, a rather persistent material. Researchers therefore took a look at Pleurotus ostreatus (aka oyster mushroom) because it grows on dead or dying trees in the wild using enzymes that break down cellulose.
Researchers found that Pleurotus broke down 90% of the material within two months. Within four, they are degraded completely. While impressive, the diapers were soiled only with urine, not ***. A healthy person's urine is sterile and researchers also treated the diapers with steam, to make sure. Such treatment would kill the nasty bugs in faeces. The researchers also indicate that Pleurotus grown in this manner could, to help recoup costs, be sold for food, and thus their caution in sterling the "growth medium" for the mushrooms.
While the willingness of the public to accept such mushrooms is questionable, the effectiveness of the degradation by the mushrooms on the "disposable" napkins is impressive.
The study can be found at http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VFR-52JK5MB-1&_user=10&_coverDate=04%2F06%2F2011&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=0a25b740fc0fc6a6b05d5456dad6a5d3&searchtype=a