Which of the following grocery bags causes the least harm to the environment?
A 2011 study by the United Kingdom's Environment Agency evaluated 9 categories of environmental impacts caused by grocery bags and found that reusable plastic bags cause significantly less harm in all 9 categories than the others. The study also found that disposable plastic bags cause less harm in all 9 categories than reusable cotton bags and disposable paper bags. The study did not account for the environmental impacts of washing reusable bags, which is recommended because they can harbor pathogens through meat drippings and other food remnants. Per the study, "The environmental impact of carrier bags is dominated by resource use and production. Transport, secondary packaging and end-of-life processing generally have a minimal influence on their environmental performance."