Connaitre ses droits

The deception of plastic called "biodegradable"

Written by Administrator Saturday, 28 May 2011 05:38

A rush ... An impasse: the plastic bags "biodegradable" do not have the environmental virtues attributed to them. Indeed, the version of "green" polyethylene could be much more harmful than expected.

Polyethylene bags are one of the most commonly used materials in the world, to the point where the waste of plastic bags are one of the prominent symbols of the impact of man on his environment. In response to the ecological threat of plastic waste, the industry is riding the fashion of plastic called "biodegradable".

The plastic "biodegradable" plastic is, in theory, can be destroyed by microorganisms (bacteria or fungi) in water, carbon dioxide (CO2) and some biomaterials. Warning! The biodegradable plastic is not necessarily made from biomaterials (such as plants). Several types of plastic "biodegradable" are made from petroleum, like ordinary plastic.

If these plastic bags "degradable" disintegrate into small fragments in the environment, these fragments can last a long time and no studies on their long-term evolution is available. Indeed, these products are labeled "biodegradable" without any reference is made to the time required for their full biological dégadation.

"The literature on degradable polyethylene is certainly dense but no evidence of serious decline," says Ann-Christine Albertsson, the main contributor to critical studies and a researcher at the Swedish Royal Institute of Technology (KTH) in Stockholm on polymers. "These plastics degrade well in a way they lose some of their properties, but there is no evidence that this process is beneficial to the environment."

Transition metal additives such as iron and cobalt accelerates the oxidation of polymers of ethylene and degradability or biodegradability of these materials is readily highlighted on food packaging or plastic bags. A study published in mid-April 2011 in Environmental Science & Technology (1), alerts us to the fact that "degradable polyethylene" is far from established.

Developing countries like China to begin as degradable polyethylene, is the researcher KTH. The GOI, interested, have sent one of its senior researchers to work alongside Ann-Christine Albertsson. Some countries are turning to products actually based biodegradable polylactide starch, but their cost remains an obstacle. Products made of paper, moreover, are not desirable because of deforestation.