Plastic bag

A German plastic shopping bag, freshly folded (left) and used (right)

Milk bags

Different meat products of Thailand in plastic bags

American and European patent applications relating to the production of plastic shopping bags can be found dating back to the early 1950s, but these refer to composite constructions with handles fixed to the bag in a secondary manufacturing process. The modern lightweight shopping bag is the invention of Swedish engineer Sten Gustaf Thulin.[7] In the early 1960s, Thulin developed a method of forming a simple one-piece bag by folding, welding and die-cutting a flat tube of plastic for the packaging company Celloplast of Norrköping, Sweden. Thulin's design produced a simple, strong bag with a high load-carrying capacity, and was patented worldwide by Celloplast in 1965.

From the mid-1980s onwards, plastic bags became common for carrying daily groceries from the store to vehicles and homes throughout the developed world. As plastic bags increasingly replaced paper bags, and as other plastic materials and products replaced glass, metal, stone, timber and other materials, a packaging materials war erupted, with plastic shopping bags at the center of highly publicized disputes.

In 1992, Sonoco Products Company of Hartsville, SC patented[8] the "self-opening polyethylene bag stack". The main innovation of this redesign is that the removal of a bag from the rack opens the next bag in the stack.

The number of plastic bags used and discarded worldwide has been estimated to be on the order of one trillion annually.[9] The use of plastic bags differs dramatically across countries. While the average consumer in China uses only two or three plastic bags a year, the numbers are much higher in most other countries: Denmark: four; Ireland: 20;[10] Germany: 65; Poland, Hungary, Slovakia: more than 400.

A large number of cities and counties have banned the use of plastic bags by grocery stores or introduced a minimum charge. In September 2014, California became the first state to pass a law banning their use. Local manufacturers of plastic bags, under the legislation, would receive financial support to assist them to make more durable multi-use bags, that would be sold by grocery stores rather than given away, as were the plastic bags. In India, the government has banned the use of plastic bags of a thickness below 50 microns.[11] In 2018, Montreal, Canada, also banned plastic bags with Ottawa expected to also put the ban into effect.[12]

Compostable bag from a grocery store in Tulsa, Oklahoma

Plastic bags are mostly made out of petroleum products and natural gas. 8% of the world's petroleum resources are used for creating plastic bags at 12 million barrels of oil a day. Half of that is used as materials to make them, and the other half for energy to make them. At this rate, it will soon run out, impacting many things that depend on the resource. Not to mention all the air pollution it causes.[13]

Non-compostable plastic bags can take up to 1000 years to decompose. Plastic bags are not capable of biodegradation but rather they photodegrade, a process by which the plastic bags are broken down into smaller toxic parts. In the 2000s, many stores and companies began to use different types of biodegradable bags to comply with perceived environmental benefits.[14][15]

When plastic shopping bags are not disposed of properly, they can end up in streams, which then lead them to end up in the open ocean. To mitigate marine plastic pollution from single-use shopping bags, many jurisdictions around the world have implemented bans or fees on the use of plastic bags.[16] An estimated 300 million plastic bags end up in the Atlantic Ocean alone.[17] The way in which the bags float in open water can resemble a jellyfish, posing significant dangers to marine mammals and Leatherback sea turtles, when they are eaten by mistake and enter the animals' digestive tracts.[18] After ingestion, the plastic material can lead to premature death. Once death occurs and the animal body decomposes, the plastic reenters the environment, posing more potential problems.[17]

Huge masses of plastic waste are arriving in the oceans per annum and causing several damages which include risk of marine species, disturbance in food web ultimately effecting marine ecosystem, several microbial and alien species colonize on plastic particles enhancing their harmfulness, and plastic particles driven by winds form garbage patches in various parts of the oceans.[19]

Marine animals are not the only animals affected by improper plastic bag disposal. Sea birds, when hunting, sense for dimethyl sulfide (DMS) which is produced by algae. Plastic is a breeding ground for algae, so the sea birds mistakenly eat the bag rather than the fish that typically ingests algae. (National Geographic)[20]

Plastic bags do not do well in the environment, but several government studies have found them to be an environmentally friendly carryout bag option. According to the Recyc-Quebec, a Canadian recycling agency, "The conventional plastic bag has several environmental and economic advantages. Thin and light, its production requires little material and energy. It also avoids the production and purchase of garbage/bin liner bags since it benefits from a high reuse rate when reused for this purpose (77.7%)."[21] Government studies from Denmark[22] and the United Kingdom,[23] as well as a study from Clemson University,[24] came to similar conclusions.

Even though the bags are plastic, they typically cannot be recycled in curbside recycling bins. The material frequently causes the equipment used at recycling plants to jam, thus having to pause the recycle machinery and slow down daily operations.[25] However, plastic bags are 100% recyclable.[26] To recycle them the user needs to drop them off at a location that accepts plastic film. Usually, this means taking them back to the grocery store or another major retail store.[27]