Plastic shopping bag
From Plastics Wiki, free encyclopedia
Plastic shopping or "carrier" bags are common in most countries. They are made of polyethylene (low-density or more "crinkly" high-density). Plastic bags are cheaper and lighter in weight than their paper counterparts, and they do not weaken when wet. One disadvantage of these bags in use is their tendency to spill when items shift inside, due to their low stiffness and lack of a flat base. Plastic bags are commonly reused as either garbage bags or bin-liners, and can be recycled along with other plastic waste. Plastic bags are notorious for becoming litter, and because of their light weight, wind can blow them for long distances.
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Biodegradable plastic bags
However, Oxo-biodegradable plastic is now available. It has the same strength and other qualities as conventional plastic, but degrades by a process of oxidation, initiated by putting a small amount of additive into the conventional plastic. There is little or no additional cost and there is no need to re-equip factories nor re-train the workforce.
The plastic is consumed by bacteria and fungi after the additive has reduced the molecular structure, and it is therefore biodegradable. This process continues until the material has biodegraded to nothing more than CO2, water, and humus, and the time taken for oxo-biodegradable plastic to degrade can be ‘programmed’ at manufacture to be as little as a few months or as much as a few years. Degradation starts immediately after exposure to air, but products can be vacuum-packed for delivery to suspend degradation until needed for use.
Oxo-biodegradable plastic can be safely used for direct contact with food. The polymers from which oxo-biodegradable plastics are made (unlike PVC)do not contain organo-chlorine, nor do they emit methane nor nitrous oxide when they degrade.
Hydro-biodegradable or “starch-based” plastics made from crops are not a preferred alternative. They are much too expensive, they are not strong enough, and cannot be recycled in a normal plastic waste stream. They will not readily degrade unless in a highly microbial environment such as a compost heap, so are not much use in the fight against litter. Nor are they really “renewable” because hydrocarbons are burned by autoclaves used to ferment and polymerise the material and by the agricultural machinery and road vehicles employed; also by the manufacture and transport of fertilisers and pesticides. Further, hydro-biodegradable plastic can emit both methane and carbon dioxide (which are both greenhouse gases) when it degrades. Methane is 23 times more potent for global warming than CO2.
Policymakers need always to consider what happens to waste plastic products which escape collection, as it is impossible for industry and government to ensure that they are all collected - and even if collected to ensure that they are all recycled. They should all therefore be made from oxo-biodegradable plastic, except for very long-life items. If collected they can be recycled, composted, or incinerated with energy recovery, but if not collected they will degrade and disappear, leaving no harmful residues.
Reusable plastic bags
Long-term re-usable bags are much thicker and more expensive, and a large number of them would be required for the weekly shopping of an average family. They are not hygienic unless cleaned after use. Whilst sometimes called “Bags for Life” they have a limited life, depending on the treatment they receive, and become a very durable form of litter when discarded. However, for those who believe in long-term re-usable bags, they can be made from extended-life oxo-biodegradable plastic.
Comparison with paper bags
The process of making paper bags causes 70% more atmospheric pollution than plastic bags. Paper bags use 300% more energy to produce, and the process uses huge amounts of water and creates very unpleasant organic waste. Template:Citeneeded When they degrade they create methane and carbon dioxide, both of which are greenhouse gases. A stack of 1000 new plastic carrier bags would be around 2 inches high, but a stack of 1000 new paper grocery bags could be around 2 feet high.
Current approaches
Countries where shopping bag pollution has become a problem have sought to address it in various ways.
Total ban
- Some Indian states (Maharashtra, Himachal Pradesh…) band the manufacture, sale and use of all plastic bags
- Bangladesh
- Taiwan
- Corsica (in France)
Partial ban
India - In the Delhi Capital Territory, legislation makes the use of non-biodegradable plastic bags a punishable offence.
Mauritius - has banned the import or local manufacture of non-degradable plastic bags, and has specified that only oxo-biodegradable can be considered degradable.
Economic incentive against the use of some types of plastic bags
Malta - charges a lower tax on bags made from degradable plastic.
Barbados charges 60% import surtax on non-degradable plastic bags imported from outside CARICOM, but only 15% on oxo-biodegradable plastic bags.
Australia In Australia, shoppers are now encouraged to buy "green bags" which can be reused time and time again. These may cost $1-$2, which is much more than the lightweight bags. These bags come in green, black and blue. Some of the "green bags" are insulated for the carrying of hot or cold items.
Ireland On March 4, 2002 the Republic of Ireland introduced a 15 cent levy on every plastic shopping bag. This led to people cutting down on plastic shopping bags by 95% but the overall consumtion of plastic has not reduced. They have switched to reusable plastic bags, bin liners and refuse sacks. The money gathered by the levy was used for environmental initiatives.
Other
South Africa - Mohammed Valli Moosa, the Environment and Tourism Minister of South Africa, jokingly named them the "national flower" of that country, and worked to introduce a minimum legal thickness of 30 micrometres to increase their cost, reusability, and recyclability.
None or nearly
United States - Plastic bags largely displaced paper bags as the most common type of shopping bag during the late 1980s and early 1990s. There has been no broad action against the litter problem, although some local governments have enacted ordinances, and many stores allow customers to return the bags for recycling. Empty bags carried on the wind are popularly known as "urban tumbleweed." People are now becoming aware of oxo-biodegradable plastic.
Japan - Almost any store you visit in Japan, from convenient stores to street vendors, will also net you a free plastic bag for your purchase. Although there are some supermarkets (like Kyoto Co-op) which charge for plastic bags, this is by no means the norm. Many supermarkets (like Izumiya) will give you extra points on your point-card if you bring your own bag.
Canada - Many groceries now encourage buying reusable bags for 1$ or 2$.
See also
External Links
- www.reusablebags.com.au - Australian site about reusable bags.
- www.reusablebags.com - A site with news and information about reusable shopping bag usage worldwide.
