Now comes another story wherein one of the fundamental tenets of the "Plastics vs. the Environment" conflict turns out to be not so much of a sure thing. These interesting instances of elegant theories slain by ugly facts seem to be recurring with fair regularity.
Back in December, this blog took note of a study that found the total life-cycle environmental impact of petroleum derived polyolefins to be less than that of "green" biopolymers such as PLA and PHA.
Then last month, we pointed out the work of an Oregon State University oceanographer who finds the Great Pacific Garbage Patch to be far less menacing in its reality than in its media hype.
Now, we have a study by the UK's Environment Agency that analyzes the life-cycle carbon emission "footprint" of various types of supermarket bags. Guess what? The best alternative turns out to be the thin-gage HDPE bag so often deprecated by environmentalists.
Plastic or paper? The study concludes that a paper bag would need to be re-used three times to meet the standard set by the HDPE bag.
Re-usable cotton bags must be the answer, right? Well, not so much. According to the UK study, the manufacture of the cotton bag is so carbon-intensive that it must be used 173 times to catch up to the HDPE alternative. But (again, according to the study) the typical cotton bag has a life expectancy of 51 uses.
Of course, this study looks at only one dimension of the problem. We still have to develop effective ways to capture single-use HDPE bags so they can't escape into the wild and litter the beaches, etc.
Our primary point is that the conventional wisdom ("Plastic = Bad!") that is so often the starting point for shrill debates about our industry's stock-in-trade is very likely fallacious. We shouldn't allow such assumptions to go unchallenged.