Many hardcore hiker-campers question the inherent biodegradability of any material. Well, here's the rule: any material that comes from nature will return to nature, as long as it is still in a relatively natural form. Therefore any plant-based, animal-based, or natural mineral-based product has the capability to biodegrade, but products made from man-made petrochemical compounds generally do not (at least not for a very long time).  When a man-made compound is formulated in a laboratory, combinations of elements are made that do not exist in nature, and there are no corresponding microorganisms to break them down.

A leaf takes approximately a year to become part of the forest floor.  An iron shovel, on the other hand can take decades to rust away to nothing, and a large tree can take many decades to completely break down.  Common sense tells us that any material will ultimately biodegrade, even if it takes centuries.  So what is the proper rate for a material to be biodegradable? It really depends on the material itself. The leaf example suggests that the proper rate is that which is appropriate to the ecosystem.  A liquid going into a waterway should biodegrade fairly quickly, whereas there's no harm done if it takes a while for a newspaper to break down.  Plastics, on the other hand, will not biodegrade in anyone's lifetime, and certainly will never break back down into the petroleum from which it was made.

To be truly biodegradable, a substance or material should break down into carbon dioxide (a nutrient for plants), water, and naturally occurring minerals that do not cause harm to the ecosystem (salt or baking soda, for example, are already in their natural mineral state and do not need to biodegrade).

Many products that are inherently biodegradable in soil-such as tree trimmings, food wastes, and paper-will not biodegrade when we place them in landfills because the artificial landfill environment lacks the light, water, and bacterial activity required for the decay process to begin. The Garbage Project, an anthropological study of our waste conducted by a group at the University of Arizona, has unearthed hot dogs, corn cobs, and grapes that were twenty-five years old and still recognizable, as well as newspapers dating back to 1952 that were still easily readable. When the conditions needed for biodegradable materials to naturally biodegrade are not provided, major garbage problems are the result.

Soap, for example, is a natural, organic product that is inherently biodegradable. The soapy gray water from a single household may biodegrade easily in a backyard, however, if that same soap went down a sewage line that fed into a waterway along with the soap used by a million or more residents that live along that waterway, there may be waves of soapsuds on the beaches, simply because more soap would be going into the waterway than it has microorganisms to degrade it.

Oil spills are devastating not because oil doesn't biodegrade, but rather because the amount of oil is much greater than the number of microorganisms available to degrade it.  It has been estimated that it will take 50 years for the oil spilled in 1989 by the Exxon Valdez to degrade. Lakes and streams have become polluted because the amount of sewage dumped into them has been overwhelming.  As much as we need to consider the biodegradability of the product, we need to consider the capacity of the system the biodegradable substance or material is being placed into.

Those who have attempted to define biodegradable for product labels run into the same dilemma encountered when defining recyclable: should a product be called biodegradable if it inherently has the ability to biodegrade, or should it only be called biodegradable if it also is commonly disposed of in a way in which it really will biodegrade? For example, should a paper grocery bag be labeled biodegradable? It will biodegrade if placed in nature, however it won't biodegrade in a landfill because the conditions aren't right.

How Long It Takes Some Products To Degrade
Here's how long it takes for some commonly used products to degrade - when they're scattered about as litter: