Biodegradable bags are bags that can break down when bacteria and other small living things are present.

Each year, about 500 billion to 1 trillion plastic bags are used around the world.

Distinguishing "biodegradable" from "compostable"

The word "biodegradable" has a different meaning than "compostable." Biodegradable means an object can be broken down by bacteria or other living things. However, in the plastic industry, "compostable" means something can break down in environments with oxygen, as long as the temperature and humidity are carefully controlled. According to ASTM International D 6002, compostable materials must fully break down in a composting site. After breaking down, they should not be visible and must turn into carbon dioxide, water, inorganic materials, and plant matter at the same rate as other known compostable materials.

The presence of inorganic materials means the final product cannot be called compost or humus, which are made only of organic material. Under the ASTM definition, the only requirement for a plastic to be called compostable is that it breaks down at the same speed as other materials already known to be compostable.

Plastic bags can be made "oxo-biodegradable" by using regular plastic materials like polyethylene or polypropylene. These plastics include a special chemical that starts breaking down the plastic through a process called oxidation, which eventually allows the plastic to biodegrade.

Trade associations

The industry group for oxo-biodegradable plastics is the Oxo-biodegradable Plastics Association. This group checks if products meet the ASTM D6954 standard or, beginning on January 1, 2010, the UAE 5009:2009 standard.

For compostable plastics, the industry groups include the Biodegradable Products Institute, "European Bioplastics," and the SPIBioplastics Council. Products are certified as compostable for industrial composting in the United States if they follow the ASTM D6400 standard. In Europe, products must meet the EN13432 standard to be certified as compostable.

Materials

Most plastic bags are made from materials derived from corn, such as polylactic acid mixtures. Biodegradable plastic bags are now as strong and dependable as traditional plastic bags, which are usually made from polyethylene. Many bags are also made from paper, organic materials like Manila hemp, or polycaprolactone.

According to Ramani Narayan, a chemical engineer at Michigan State University and a science consultant for the Biodegradable Plastics Institute, the term "biodegradable" is widely used but often misunderstood. He explains that biodegradable plastics in the Great Pacific Garbage Patch break into tiny pieces that can be eaten by marine life, entering the food chain.

A promising material for making biodegradable bags and packaging is starch. Starch has several advantages, including its ability to be renewed naturally, its cost-effectiveness, and the ease of producing customized bags. If bioactive compounds, such as antioxidants, are added to starch-based materials, they can create active packaging that helps preserve food.

Recycling

In-plant scrap is often able to be reused, but recycling materials after they are used by consumers is more difficult. Materials made from natural sources, such as bio-based polymers, can mix with and interfere with the recycling of more common plastics. Although companies that make oxo-biodegradable plastic say their plastic bags can be recycled, many recyclers do not accept them because there is not enough research on how well products made from recycled materials with these additives work over time. Additionally, the Biodegradable Plastics Institute (BPI) explains that the mix of additives in oxo-biodegradable plastic films changes a lot, which makes the recycling process even more complicated. The SPI Resin identification code 7 is used for these materials.

Marketing qualification and legal issues

Some plastics need sunlight, oxygen, or a long time to break down or decompose. Because of this, the U.S. Federal Trade Commission (FTC), through its "green guide," requires products to be clearly labeled with information about their limits in performance.

The FTC explains that there are no simple tests to determine if a plastic bag is truly "biodegradable." To meet U.S. trade rules, manufacturers must include details on the conditions needed for biodegradation, how long it takes, and the final results.

In 2007, California made it illegal to use the term "biodegradable bags" unless the claims are supported by strong and trustworthy evidence. This rule aims to prevent misleading consumers about the environmental effects of degradable, compostable, or biodegradable plastic bags, food containers, and packaging.

In 2010, an Australian company that made unproven or unclear claims about the biodegradability of its plastic bags was fined by the Australian Competition & Consumer Commission, which serves a similar role to the FTC in the United States.

Recently, the Biodegradable Products Institute and some companies claimed their products can break down in composting facilities that reach 140°F (60°C). However, the Vermont attorney general found these claims to be misleading and took legal action against companies that made false claims about compostable plastic products.