Top | Sift

The life-cycle assessment

(article, Culinate staff)

Plastic bags. They're so useful. They're so ugly when they're stuck in tree branches. And they're so bad for the environment. No wonder numerous U.S. cities have imposed taxes or outright bans on them.

But David Tyler, a University of Oregon chemistry professor, begs to differ from the conventional wisdom. According to Tyler, the total environmental impact of plastic bags is less than that of paper bags — and paper, of course, is what most grocery stores now offer shoppers instead of the reviled plastic version.

Plastic, Tyler told Oregon Public Broadcasting's Ecotrope department, is actually less evil for the environment than many traditional materials, including paper, glass, and cotton. Which means that the most eco-friendly shopping bag is a reusable one made from recycled plastic.

Tyler studies "life-cycle assessments," a field that has documented, among other calculations, that food miles — the distance that food travels to reach consumers — aren't such a big deal after all. And that owning a pet dog is worse for the planet than owning an SUV, thanks to the amount of food consumed by the dog over its lifetime.

But, Tyler noted, life-cycle assessments "don't consider cost, technical performance, or the political and social acceptance of the items in question." Which is why we still hate seeing plastic bags stuck in trees.