Production and Distribution

• Plastic bags are made from crude oil. The oil is heated to release ethylene gas. This is converted to polyethelene, a gelatinous substance, which is forced through holes to make strings, which are cut, heated and molded into bags. The production process costs four times the energy of producing paper bags.
  
  Five trillion plastic bags are made each year. That's enough demand to use 0.2 percent of world oil consumption. Most plastic bags are made overseas, in China, India, Thailand and Malaysia.
  
  

Use

• Most plastic bags get used only briefly, once, maybe twice, to carry purchased items. A typical free supermarket bag in the UK is used for an average of 20 minutes before it is thrown away. UK statistics show 216 plastic bags per capita are handed out per year.
  
  In 2008 China, the largest plastic bag consumer, begain banning shops from offering free plastic bags, to encourage shoppers to return to their own cloth bags. In the U.S., some stores provide a meager discount if you use your own bags.
  
  

Recycling

• A third of British people reuse plastic bags as trash liners. Another third reuse them for shopping. About 5 percent turn them in to be recycled as new plastic products. Nevertheless, U.K. and U.S. facilities are limited in their ability to recycle the volume coming through, partly because of the labor resources needed to separate the different types of plastic. Further complicating the recycling process is that the dyes on plastic bags lead to grey or black plastic when recycled.
  
  Recycling may not even be worthwhile to the environment. While producing plastic bags uses four times the energy of paper bag production, recycling them uses 85 times as much.
  
  

Ocean Life

• Two Trash Gyres in the North Pacific (Courtesty: Gainesville State College)
  
  Plastic bags that land in waterways eventually find their way into the ocean. This is signficant because there they are slowly broken down by ultraviolet rays from sunlight, but with no loss of material. The plastic is degraded only into smaller pieces, which become bite-size to smaller and smaller animals.
  
  How much plastic, from bags or otherwise, is floating in the oceans? One count quoted in "The World Without Us" puts tiny plastic particles as more prevalent than plankton. A count by Greenpeace found that the Pacific Gyre, a circulating dead zone in the Pacific, contains more than a million pieces of plastic microdebris per square kilometer of ocean surface.
  
  

Ingestion

• Necropsy on Seabird Found Dead Reveals Trapped Plastic (Courtesy: Pomona College)
  
  After ingestion, the pieces of plastic no longer degrade due to exposure to the sun and can become trapped in the digestive tract of the animal. Fish and emaciated seabirds have been cut open to reveal plactic pieces trapped in their stomachs. The proportion of ingested plastic coming from plastic bags, however, is small -- not because they don't swallow it but instead because there is so much other plastic litter in the oceans.
  
  

Lifespan

• It is not known how long plastics last, since they have only been around since the 1930s. Estimates have been placed in the hundred to the thousands of years. Therefore, where the plastic bag's life cycle ends is only an educated guess.