Friday, December 18, 2009

Facts about Polythene carry bags

Plastic Carry Bags are generally made out of polyethylene (polythene) which is used in contact with food stuffs, pharmaceuticals and drinking water and its use in these critical areas is approved by the regulatory authorities across the world including that in India like Bureau of Indian Standards (BIS) (Refer BIS Specification IS 10146:1982 – Reaffirmed on Feb-2003). Plastic Carry bags have contributed significantly in creating a sustainable, cost effective, energy efficient, hygienic and environmental friendly packaging system and for carrying, storing and packing various types of commodities/products including food products. The attributes, which have made the use of plastics safe and popular as a packaging material in general and as a carry bag in particular, are:
• Non toxic characteristics, inertness and chemical resistance.
• Excellent barrier properties and water-proof characteristics.
• Safe in handling due to non-breakability and light in weight.
• Transparency, allowing easy visibility of content being carried/stored/packed.
• Can also be opaque to protect the content from exposure to sunlight, when required.
• Resistance to bacterial and other microbial growth.
• Pilfer proof characteristics etc.
Plastic carry bags due to these properties ensure that the products of mass consumption are delivered to the consumers in the best, hygienic and economic fashion. Being inert in nature, they do not pose any health hazard. All plastics in general meet the requirements of both National and International standards like BIS, FDA etc.
Plastic carry bags and ancillary products add convenience to day-to-day life. They are essential for packaging of bread, confectionery items, all range of Farsan/Namkeen and bakery products in view of its superior properties and cost effectiveness. All these products are very sensitive to moisture and loose taste and quality within no time. Hygroscopic edible products like sugar, salt, jaggery and many other food items susceptible to moisture cannot be effectively packed in alternative materials without sacrificing the quality or cost of packaging. Over years plastics packaging have played a major role in protecting and increasing the shelf life of these products. For carrying fish, meat, poultry and other wet food products, plastic bags are most suitable and no other alternative packaging can substitute them.

Plastic bags generate 60% less greenhouse gas emissions than uncomposted paper bags and 79% less greenhouse gas emissions than composted paper bags. The plastic bags generate 3,097 tons of CO2 equivalents per 100 million bags, while uncomposted paper bags generate 7,621 tons, and composted paper bags generate 14, 558 tons, per 100 million paper bags.
Life Cycle Inventories for Packaging, Vol. 1, SAFEL, 1998

Plastic grocery bags consume 40% less energy during production and generate 80% less solid waste after use than paper bags. (US EPA)

Paper sacks generate 70% more air pollutants and 50 times more water pollutants than plastic bags do. US EPA.

It takes 91% less energy to recycle a kilogram of plastic than a kilogram of paper (US EPA)

Transporting 150,000 nos. plastic carry bags of minimum stipulated size (20X30 cms) of 40 micron thickness (weighing~600 kgs) would require one small tempo, whereas similar size and number of paper bags would require more than 10 such tempos for delivering the bags. Consider the extra fuel and cost it would need!

A scientific comparison between paper and polyethylene is shown below:

Environmental burden

Polyethylene

Paper

Energy (GJ) for manufacture

29

67

Air pollution

SO2

9.9

28.1

NOx

6.8

10.8

CHx

3.8

1.5

CO

1

6.4

Dust

0.5

3.8

Waste water burden

COD

0.5

107.8

BOD

0.02

43.1

(Source: Fabbri, A in Scott, G and Gilead , D., editors, Degradable Polymers, Principles and Application, Chapman & hall, 1995, Chapt.)

Moreover production of paper is dependent on availability of wood pulp for which trees have to be felled causing further environmental concern.
Plastic and Jute Bags
A comparison of Plastic Bags with Jute Bags in terms of Life Cycle Analysis reveals that

Energy Saving during manufacture of raw materials, production and transportation of plastic bags compared to jute bags is 81%.

Environmental Burden with respect to Air and Water pollution during Production of Raw Material and Bags for Plastic Bags and Jute bags are given below:

Environmental Burden

Jute Bag

Plastic Bag

Air Emission

CO

kg

54.3

0.6

CO2

kg

6610.2

760.0

SOx

kg

134.8

5.2

NOx

kg

68.1

4.8

CH4

kg

39.5

3.2

HCl

kg

5.3

0.0

Dust

kg

67.6

1.4

Water Emission

Suspended Solids

kg

352.3

0.2

Chlorides

kg

4535.5

0.1

The environmental burdens during transportation of the finished bags are as below:

Emission

gm/km

Excess emission for Jute bags

Plastic Bags

CO2

781.0

11107.3

Taken as Basis

CO

4.5

64.0

Taken as Basis

HC

1.1

15.6

Taken as Basis

NOx

8

113.8

Taken as Basis

Particulates

0.36

5.1

Taken as Basis

Total regulated tail pipe emission

13.96

198.5

Taken as Basis

The values are for packaging of one lac MTs of Atta. Source: Centre for Polymer, Science and Engineering, IIT - Delhi

Consider the enormous environmental burden generated by Jute bags, which are not visible to naked eyes though, in comparison to Plastic Bags!
Plastic and Textile Bags
When plastics and textile are compared, following data is revealed:

Plastics manufacturing consumes 400 kwh/mt while composite textile mills consume 1310 kwh/mt.

Textile contributes 30% SOx (Second Highest by Any Sector) and 23% NOx (Highest by Any Sector) (Source : Warmer Bulletin, July 01) Millions of KW of energy is saved and the atmosphere is less polluted when Plastic Carry bags are used in place of Textile bags.

Biodegradable/Compostable Plastic Bags
Biodegradation/Composting, by definition releases CO2 and CH4 - both Green House Gases, in to the atmosphere. Moreover, process takes place only when suitable environment is available. Use of biodegradable / composting plastics is thus restricted to specific applications worldwide.


What is the Real Issue?
Our poor littering habits coupled with insufficient infrastructure for waste management has created the disposal problem of solid waste, including the plastic waste in the urban areas. However, available data reveals that the MSW in major cities in India contains around 5% plastics waste, balance being Paper, Compostable Matters, Sand, Silt, Sanitary Diapers and Construction Debris etc. Hence Plastic Bags cannot be singled out as the sole reason for clogging of drains.


Discontinuation of Plastic bags is no solution and will rather multiply the problem many fold. This will add to the woes of common man as the so called alternatives are unviable, costly and place greater burden on the environment.


To discourage illogical use and to encourage the waste pickers for collection and recycling process, the regulatory bodies have already specified the minimum thickness and size of plastic carry bags.


Therefore, the challenge facing us is to improve the solid waste management system and address littering habits of masses by educating them and creating awareness. The solution lies in Segregation of Waste at Source and arrangement for Recycling of all recyclable waste. Plastics Bags are 100% recyclable.