Compostable bags are made using organic matter and don’t leave behind any toxic matter once broken down. Temperature, moisture, heat and air form some of the specific criteria required for the product to break down. It is for this reason compostable bags don’t break down as intended in landfill.
To be classified as a compostable bag they must comply with Australian Standard 4736 that states, among other criteria, that the products must reach a minimum of 90% biodegradation of plastic materials within 180 days of compost.
Biodegradable bags have chemical compounds added to them in order to aid in the breakdown process. They break down with the help of naturally occurring microorganisms.
Biodegradable plastics typically take between three to six months to break down once exposed to environmental conditions but can also take substantially longer depending on the environment. Once broken down, biodegradable products have been known to leave some toxic elements behind (often referred to as micro plastics).