The following is part of the environmental themed advice column EarthTalk® by the Editors of the non-profit publication E/The Environmental Magazine that we'll be featuring here on CL's Green Community.
Dear EarthTalk: I’ve heard conflicting reports regarding how long it really takes for a plastic grocery bag to decompose. Can you set the record straight? — Martha Blount, San Diego, CA
Researchers fear that such ubiquitous bags may never fully decompose; instead they gradually just turn into smaller and smaller pieces of plastic. The most common type of plastic shopping bag is made of polyethylene, a petroleum-derived polymer that microorganisms don’t recognize as food and as such cannot technically “biodegrade.” The U.S. Environmental Protection Agency defines biodegradation as “a process by which microbial organisms transform or alter (through metabolic or enzymatic action) the structure of chemicals introduced into the environment.” In “respirometry” tests, whereby experimenters put solid waste in a container with microbe-rich compost and then add air to promote biodegradation, newspapers and banana peels decompose in days or weeks, while plastic shopping bags are not affected.
This article appears in Sep 16-22, 2010.
