A Survey on the Economic Effects of Los Angeles County’s Plastic Bag Ban

Policy Reports | Energy and Natural Resources

No. 340
Thursday, August 16, 2012
by Pamela Villarreal and Baruch Feigenbaum

Environmental Effects of Plastic and Reusable Bags

The main reason policymakers give for banning thin-film plastic bags is the impact of the bags on the environment. However, the environmental effects of plastic bags are negligible — and in number of ways plastic bags are environmentally preferable to the alternatives.

Energy and Water Consumption. Producing plastic, paper and other types of bags requires energy, but some of that energy can be recovered if bags are recycled through combustion13. plastic bags and 1,500 compostable bags (for equivalent carry capacity):  

  • Traditional plastic bags require only 182,361.4 kcal of energy to produce, but some 2,581.3 kcal of energy can be recovered through combustion.
  • By contrast, an alternative to traditional plastic bags, compostable plastic bags made of starch and other materials,11 require more than twice as much energy (494,741.9 kcal) to produce, but only 3,477.5 kcal can be recovered through combustion.
  • Paper bags fare the worst, with more than three times as much energy consumption as plastic bags (626,672.9 kcal), whereas only 6,859.5 kcal can be recovered through combustion.

Landfill Waste. The same EPA study compared the weight of material entering the municipal waste stream, net of the material consumed by the combustion process, per 1,000 paper bags, 1,500 plastic bags and 1,500 compostable bags (for equivalent carry capacity):

  • The production, use and disposal of plastic bags produces a net 15.51 pounds of municipal solid waste.
  • Compostable plastic bags produce 42.32 pounds of municipal solid waste.
  • Paper bags produced the most municipal waste, nearly 75 pounds.

Thus, traditional plastic bags recover the largest percentage of energy. They also leave behind the smallest amount of municipal solid waste.

Water Use. A study of Australian shopping bags found that of various alternatives — single-use plastic bags, compostable plastic bags, paper bags and reusable bags — paper bags had the worst energy and environmental impact with respect to global warming, land use, water use and solid waste.12  The study measured environmental impacts for the equivalent number of different types of bags — based on a functional unit of 520 paper, single-use plastic or compostable plastic bags, or 4.1 cloth bags.13  Production and use of plastic and compostable plastic bags consumed about 13.7 quarts of water (net), whereas cloth bags consumed about 52.8 quarts.14 The study found that single-use bags contributed 5.95 pounds of solid waste, whereas compostable plastic bags contributed only 1.83 pounds of solid waste. But reusable cloth bags contributed the most solid waste: 7.24 pounds.

Plastic Bags versus Paper Bags. Plastic bags are significantly more environmentally friendly than paper bags. According to Use Less Stuff, an environmental advocacy group, plastic bags generate 39 percent less greenhouse gas emissions than uncomposted paper bags and 68 percent less greenhouse gas emissions than composted paper bags.15  Additionally, plastic bags consume less than 6 percent of the water needed to make paper bags. More than 16 plastic bags can be created for every one paper bag using the same amount of water. Plastic bags consume 71 percent less energy during production than paper bags. Using paper bags instead of plastic bags generates almost five times more solid waste.

The United Kingdom’s Environmental Agency evaluated nine categories of environmental impacts of paper and plastic bags. Paper bags were more environmentally harmful than plastic bags in every category: global warming potential, abiotic depletion, acidification, eutrophication, human toxicity, fresh water aquatic ecotoxicity, marine aquatic ecotoxicity, terrestrial ecotoxicity and photochemical oxidation.16

Plastic Bags versus Cloth Bags. Plastic bags are also noticeably more environmentally friendly than reusable cloth bags.

While most plastic bags are manufactured domestically, most reusable bags are produced outside the United States in places like China. These bags are then transported via gas-guzzling cargo ships to customers in the United States. Cargo ship transport is a significant generator of pollution. Additionally, as reusable bags are made from cotton and other sources that require substantial amounts of farmland to produce, the production of cloth bags leads to destruction of forests in cotton producing regions. These farms can also increase erosion and lead to pesticides in drinking water. Cloth bags are much more challenging to recycle since they contain a combination of materials including metal, cotton and other fabrics.17 

The United Kingdom’s Environmental Agency determined that cotton bags have to be used 104 times before their environmental performance surpasses that of plastic bags.18  However, the average cotton bag is only used 52 times, and some cloth bags are used much less. As a result, cloth bags have twice the negative environmental impact of plastic bags.

Litter. Studies show that plastic bags represent a tiny portion of litter and that banning them has not reduced the amount. Nationwide studies show that plastic bags constitute no more than 1 percent to 2 percent of all litter, on average.19  According to the Keep America Beautiful campaign, plastic bags are not one of the top 10 sources of litter nationwide.20  The results of litter studies in various localities are fairly consistent:

  • In Austin, Texas, for example, an evaluation of representative litter found that plastics comprised 0.6 percent of the city’s total litter — but the figure was likely high due to the inclusion of other plastic waste, such as trash bags. 21 
  • In California, a Statewide Waste Characterization Study found that banned plastic bags constitute only 0.3 percent of the waste stream in the state.22 
  • In San Francisco, surveyors found that plastic bags comprised 0.6 percent of the city’s litter before a local ban was enacted, and a year after the ban, the portion of the city’s litter attributable to plastic bags actually increased to 0.64 percent.

Recycling. A much larger percentage of plastic bags are recycled today than 10 years ago. According to a survey conducted by Moore Recycling Associates, the number of bags recovered increased 27 percent between 2009 and 2010.23  These bags made up approximately 13 percent of the total film and bag material recovered in 2010. This amounted to approximately 127 million pounds of plastic bags recycled in 2010, compared with 100 million pounds in 2009. According to the EPA, almost 12 percent of plastic bags were recycled in 2010.24  The number of bags recycled can substantially change the economic and environmental costs of the bags.

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