"But canvas bags might actually be worse for the environment than the plastic ones they are meant to replace. In 2008, the UK Environment Agency (UKEA) published a study of resource expenditures for various bags: paper, plastic, canvas, and recycled-polypropylene tote bags. Surprisingly, the authors found that in typical patterns of use and disposal, consumers seeking to minimize pollution and carbon emissions should use plastic grocery bags and then reuse those bags at least once—as trash-can liners or for other secondary tasks. Conventional plastic bags made from high-density polyethylene (HDPE, the plastic sacks found at grocery stores) had the smallest per-use environmental impact of all those tested. Cotton tote bags, by contrast, exhibited the highest and most severe global-warming potential by far since they require more resources to produce and distribute."