Kinds of Plastic Bags

There are two major types of plastic bags that are used in retail. You have the lightweight, checkout-style bags which are most commonly found in supermarkets and takeaway stores. These are made high density polyethylene (HDPE). The heavier, tougher plastic bags found in boutiques and department stores are made from low density polyethylene (LDPE). The plastic bags made out of HDPE are the most common ones to end up as pollution. This makes the landscape uglier and causes a lot of trouble. On top of that, most plastic bags take ages to degrade.

Plastic bags also present life-threatening risks to wildlife and
livestock. Turtles, whales, birds and fish are especially vulnerable.
Plastic bags floating in water can be mistaken for food. Once
ingested a bag can prevent the animal from digesting food or  submerging.

A solution for the long time that it takes for plastic to degrade are biodegradable or degradable plastic bags. Biodegradable plastic is made from plant-based materials like corn and wheat starch rather than petroleum. This means that if composted, they are degradable. Degradable plastic bags are made from petroleum products that contain metal compounds to help accelerate their breakdown. Oxygen, ultra-violet light and/or heat chemically weaken degradable plastic bags until they become brittle and fragment into smaller pieces. This process may take up to 5 years to occur. Oxo-degradable bags cannot be composted.

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Yet, for shopping bag purposes, single-use biodegradable bags and
oxo-degradable plastic bags do not yet provide a comprehensive
solution yet to the issue of single-use bags. This is because:

  • They still present a litter problem.
  • Until they have fully degraded they still pose a threat to animals that ingest them.
  • They are not suitable for recycling in mainstream recycling systems as they contaminate the recycling process.
  • If biodegradable bags are sent to landfill, they break down without oxygen to produce methane, a greenhouse gas with a warming capacity 21 times more powerful than carbon dioxide.
  • The environmental impact of oxo-degradable plastic after it has fragmented to small pieces or powder has not yet been determined.
  • It can be difficult to distinguish between different types of
    single-use bags, and therefore to decide on the most
    responsible disposal option.