Science Fair Project Encyclopedia
Plastic shopping bag
Plastic shopping bags are a common type of shopping bag in several countries. They are made of polyethylene (low-density or more "crinkly" high-density) and are cheaper and lighter in weight than their paper counterparts, but lack stiffness. Items shifting within the bag can cause the bag to fall over and spill its contents; this can be prevented by placing rigid items in the sides of the bag to provide support. The handles of these bags also have a tendency to lose elasticity and break under the weight of their contents.
Plastic bags are notorious for becoming litter. They do not biodegrade, although UV-degradable bags are easy to design and manufacturers have tried to make biodegradable versions. Because of their light weight, steady winds can blow them for long distances.
In Australia, shoppers are now encouraged to buy "green bags " which can be reused time and time again. These may cost $1-$2, which is much more than the lightweight bags. These bags come in green, black and blue. Some of the "green bags" are insulated for the carrying of hot or cold items.
A few countries have introduced laws to combat this sort of litter, for example: on March 4, 2002 the Republic of Ireland introduced a 15 cent levy on every plastic shopping bag. This led to people cutting down on plastic bags and using reusable bags. The money gathered by the levy was used to raise money for environmental initiatives.
Mohammed Valli Moosa, the Environment and Tourism Minister of South Africa, jokingly named them the "national flower" of that country, and worked to introduce a minimum legal thickness of 30 micrometres to increase their cost, reusability, and recyclability.
Plastic bags largely displaced paper bags as the most common type of shopping bag during the late 1980s and early 1990s. There has been no broad action against the litter problem, although some local governments have enacted ordinances, and many stores allow customers to return the bags for recycling. Empty bags carried on the wind are popularly known as "urban tumbleweed."
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