“Compostable,” “biodegradable,” and “bio-based” are terms with different meanings.

Defining “Compostable”

All living creatures consume resources and generate waste. In a well-balanced ecosystem, one creature’s waste is another creature’s resource. Within the Earth’s natural cycles, waste that is bio-based and compostable is a healthy, renewable nutrient to new life. Petroleum-based waste is not. In seeking to make purchases that respect the Earth, consumers must understand the different meanings of the terms “compostable,” “biodegradable,” and “bio-based.”

Meets D6400 composting standards set by the American Society for Testing and Materials (ASTM): Under a managed composting program, the product must 1) break down to carbon dioxide, water, inorganic compounds, and biomass at a rate similar to paper, 2) disintegrate into small pieces within 90 days, so that the original product is not visually distinguishable in the compost, and 3) leave no toxic residue. 1

Capable of disintegration by biological means; typically, composed of organic matter that can be readily decomposed by a wide variety of microorganisms; technically, composed of almost any material since with enough time, some microorganisms can decompose almost anything; for example, aluminum cans will biodegrade in the ocean in about 175 years, and hard plastic bottle caps will biodegrade in the ocean in about 400 years. 2

Derived from plants; derived from living matter; derived from renewable biological resources. However, products labeled as "Bio-based" are not necessarily compostable unless specified as such.

Why do these terms matter? Most people are disturbed by the thought of the Earth being covered with litter. Many seek products that will decompose quickly and completely after they are discarded. Manufacturers who recognize this concern often label their products as “compostable” or “biodegradable.” Consumers need to remain alert to deceptive practices in such labeling. The label “compostable” is regulated by industry standards that are measurable, verifiable, and certifiable. On the other hand, the label “biodegradable” is essentially meaningless, unless it is accompanied by an explanation of the conditions that allow the product to “biodegrade.” Consumers who seek to buy eco-friendly products must resist deceptive “green-washing” language from marketers.

Everything will break down eventually, although it could take a few months or it could take centuries. The label “biodegradable” on a package conveys no unique information except to say that the product’s manufacturer is attentive to the consumer’s concern about litter.

Page Notes:

  1. ASTM D6868 - 11 Standard Specification for Labeling of End Items that Incorporate Plastics and Polymers as Coatings or Additives with Paper and Other Substrates Designed to be Aerobically Composted in Municipal or Industrial Facilities; ASTM International; http://www.astm.org/Standards/D6868.htm; Retrieved April 27, 2012.
  2. Marine Debris Degradation Timeline; Center for Microbial Oceanography: Research and Education; http://cmore.soest.hawaii.edu/cruises/super/biodegradation.htm; Retrieved May 14, 2012.