Biodegradable

An organic substance that is able, under natural conditions, to break down or decompose rapidly to an inert substance, is considered to be "biodegradable."

Though there are no federal standards for the claim, according to the U.S. Federal Trade Commission (FTC), a "claim that a product or package is degradable, biodegradable or photo-degradable should be substantiated by competent and reliable scientific evidence that the entire product or package will completely break down and return to nature, that is, decompose into elements found in nature within a reasonably short period of time after customary disposal." 

According to the The Healthy House Institute: 

"Biodegradable is defined as 'the ability of natural biological decay processes to break down complex compounds into simple molecules.' This is truly an asset for any product to have—especially if it’s to be composted. However, at the present time, most potentially biodegradable trash is buried in landfills, and because of the manner in which landfills are constructed, virtually nothing in them can ever biodegrade. The tight compaction of alternating layers of trash and clay in typical landfills generally won’t permit the breakdown of materials—even when they have the innate capacity to do so under normal circumstances.

"Interestingly, in a surprising reversal of popular trends, some products are now actually said to be healthy for the environment because they will not biodegrade. Non-biodegradability is promoted as a positive feature because it helps prevent leachate (seepage) from leaving landfill sites and contaminating water supplies."