Americans use hundreds of billions of plastic bags each year. To reduce the number of bags used once and then thrown away, cities around the world have banned or taxed plastic bags. But which is more environmentally friendly: paper bags or reusable bags? Scientifically, there is no clear answer.
The main advantage of plastic bags is that they are made to be less harmful to the environment than other shopping bags. The most common thin plastic grocery bags are made of high-density polyethylene (HDPE). Although resources such as petroleum are consumed in the production of these bags, they produce less carbon dioxide emissions, waste, and harmful by-products than cotton or paper bags. Plastic bags are also relatively durable and can be reused. A number of studies on different bag options have shown that fewer resources are needed to produce plastic bags. It has also been found that plastic bags are used at least twice – once on the way home and once as a trash bag – and this is factored into the calculation of the most environmentally friendly bags.
Plastic bags are recyclable, but few people recycle them. Plastic bags are difficult to recycle, they fly away during recycling and get stuck in the machines. For this reason, many cities do not recycle plastic bags. Instead, large retailers offer bag recycling services. However, these services are based on the assumption that consumers will return their plastic bags to the store.
Bags that are not recycled do not degrade and eventually become waste. Not only do plastic bags fill up landfills and become landmarks, they also pose a threat to many aspects of the environment, including marine life and the food chain. This is because plastic bags, like other plastics, break down over time into microscopic pieces called microplastics. Microplastics are found almost everywhere – in marine life, in agricultural soils, and in the urban atmosphere.
Research into the effects of microplastics is still in its infancy and it is not yet known how they affect animals, humans, or the environment, but scientists are concerned about how this level of plastic pollution could change our planet. The study, which found that plastic bags are less harmful to the environment than paper or reusable bags, did not take into account the impact of litter and assumed that plastic bags are recycled or used as trash bags.
Paper bags have a number of advantages over plastic bags in terms of sustainability. They are easily recyclable and biodegradable, which means they can be used for composting. However, paper production is resource-intensive: it takes four times as much energy to produce a paper bag as it does to produce a plastic bag, and the chemicals and fertilizers used to make paper bags cause further environmental damage.
Studies have shown that paper bags must be used between 3 and 43 times to neutralize their environmental impact compared to plastic bags. Since paper bags are the least durable of all types of bags, it is not possible to use a bag enough times to offset its environmental impact.
However, the fact that paper can be recycled helps reduce its impact: in 2018, 68.1% of paper consumed in the U.S. was recycled, and this percentage has increased over the past decade. However, paper can only be recycled so many times, as the fibers in paper become shorter and weaker with each reuse.
Reusable bags are made from a variety of materials, but the environmental impact of producing these materials varies. A British study found that a cotton bag would have to be reused 131 times to reduce its climate change impact to the same extent as a plastic bag. To achieve the same environmental footprint (including climate change and other environmental impacts) as a plastic bag, a cotton bag would have to be used thousands of times. However, non-cotton materials perform much better in terms of sustainability. Non-woven polypropylene (PP) is another popular choice. Because of the durability of the plastic, they need to be reused about 11 times to achieve the same effect as conventional plastics.
Not only are reusable bags great for the environment, but they can also go unused because you have to remember to take them with you when you shop. The main benefit of reusable bags is that their use reduces waste on land and at sea. Studies have shown that when cities in Europe and the United States banned the use of plastic bags, the amount of plastic waste in nearby seas decreased.