Assessing the full environmental impacts of different products requires examining all aspects of their production, use, and disposal. To do this, researchers perform "life cycle assessments" that measure the "cumulative environmental impacts resulting from all stages in the product life cycle...." A 2011 life cycle assessment by Britain'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 totes, which is recommended because they can harbor pathogens through meat drippings and other food remnants.