Environmental Studies: The Common Plastic Bag

In recent decades, numerous countries have introduced legislation restricting the sale of plastic bags, in a bid to reduce littering and pollution. In the UK, in Scotland and Wales free plastic bags are no longer available in any supermarkets. Countries in Scandanavia, Germany, the US and Canada, Australia, New Zealand, Singapore etc have had years of no free plastic bags. Some large store chains have banned plastic shopping bags such as Whole Foods in the US and IKEA.

Heavy-duty plastic shopping bags are suitable for reuse as reusable shopping bags. Lighter weight bags are often reused as rubbish bags or to pick up pet litter or simply thrown away. Most countries have ‘long-life’ and cloth or bio-degradable bags, but many shops in England still offer free, copious amounts of plastic bags costing about a penny each to their shoppers.  Almost none are bio-degradable plastic bags. In fact the availability of perfectly sized and looking fruit and vegetables placed in plastic trays and wrapped in cellophane is often a norm.

The harm of these bags to the environment is proven, as well as simply being unsightly when caught up in hedgerows, trees and bushes, we know small and large animals choke on them. The most famous cases were of cows having bloated stomachs as these bags got caught in their stomachs and being indigestible. When the present Prime Minister David Cameron came to power, one of his first promises was to charge for plastic bags to reduce pollution by plastics bags – the difference is obvious and well documented just by travelling close to our neighbouring countries to England. So why the u-turn by him? The answer is of course in who funds and influences major donations and funding for political campaigns. I ask you to research this, though I hope the answer is obvious?

The modern lightweight shopping bag was the invention of Swedish engineer Sten Gustaf Thulin.  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. This basic model was then cloned or slightly altered to change the shape or colour by the addition of dyes and logos. The use of plastic bags to facilitate shopping and increase the carrying capacity limited by paper bags soon revolutionised shopping.  Do you know how people bought shopping, and still do in many countries, before the advent of plastic bags? This change is recent.

This changed when the Dixie Bag Company of College Park, Georgia, US, owned and operated by Jack W. McBride, was one of the first companies to exploit this new opportunity to bring convenient products to all major shopping stores. The Dixie Bag Company, along with similar firms such as Houston Poly Bag and Capitol Poly, was instrumental in the manufacturing, marketing and perfecting of plastic bags in the 1980s. Kroger, a Cincinnati-based grocery chain, began to replace its paper shopping bags with plastic bags in 1982, and was soon followed by its rival, Safeway.

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 centre of highly publicized disputes.

Traditional plastic bags are usually made from polyethylene, which consists of long chains of ethylene monomers. Ethylene is a derivative from natural gas and petroleum.  Can you remember how fractional distillation is used to separate different organic molecules like ethylene?  The polyethylene made by linking chains of ethylene used in making most plastic shopping bags is either low-density (resin identification code 4) or, more often, high-density (resin identification code 2).  Colour concentrates and other additives are often used to add tint to the plastic. Plastic shopping bags are commonly manufactured by blown film extrusion.

Each year millions of discarded plastic shopping bags end up as litter in the environment when improperly disposed of. The same properties that have made plastic bags so commercially successful and ubiquitous—namely their low weight and resistance to degradation, have also contributed to their proliferation in the environment. Due to their durability, plastic bags can take centuries to decompose.

Reduction, reuse and recycling 

All types of plastic shopping bag can be recycled into new bags where effective collection schemes exist, however these are costly. Increasingly recyclable or biodegradable bags are being manufactured.

Degradable Vest Style Carrier Bags

Environmentally friendly degradable carrier bags contains a degradable plastic additive to break down through oxidation, and so will degrade over time. They are not affected by moisture and can be reused time and time again. When bought in bulk, they too cost under 1p per bag.

The majority of larger UK supermarkets now offer in store recycling banks for carrier bags and some other plastic films that contain the label with the message ‘recycle with carrier bags at larger stores – not at kerbside’. Some also offer the option to hand the bags back to the driver if your shopping is delivered to your home. The following supermarkets offer in store collection points located near the tills and doors at larger stores:

• Asda
• Morrisons
• Sainsbury’s
• Tesco
• The Co-operative
• Waitrose

What else can you do with plastic bags?

1. Easily reduce the amount of carrier bags used by reusing them as many times as possible.
2. Buy life-long and foldaway re-useable bags
3. Check to see if your local recycling centre accept them for recycling

Can you think of other changes we can all do to reduce the amount of plastic we use daily?

Interested in ecology? Enrol on Level 4 Diploma in Environmental Studies .

Image Courtesy –http://www.flickr.com/photos/bensutherland/7400428126/sizes/l/in/photostream/