The dilemma of plastic bags and their substitutes: A review on LCA studies

Single-use bags have been restricted or banned in various parts of the world. The exploration of substitute alternatives such as reusable and biodegradable bags, and the use of other materials such as paper and cotton have been required. The Life Cycle Assessment (LCA) is the most widely accepted tool by the scientific community to make an environmental comparative study between different alternatives. In this study, the literature regarding LCA of bags was reviewed in order to find common conclusions, and a methodological guide for future studies. For each study, the type of bags considered, end of life treatments, the functional unit, the Life Cycle Impact Assessment methods, system boundaries, data used, locations and the results of the calculated environmental impacts are described and compared. Although some differences exist among the studies, in most analyses, reusable plastic bags are identified as the lower environmental impact alternative when enough reuses are considered. On average, the climate change index of reusable bags is equal to 27% of the value of the alternative with the highest impact in each study. For the end-of-life treatment scenarios, reuse and recycling show greater environmental benefits compared to composting, landfilling or incinerating, regardless of energy recovery. Open challenges are discussed, where several authors agree with the requirement of the development of a new index to quantify the consequences of plastic leakage into the environment.