The paper sack - food for thought

Nutrition & Food Science

ISSN: 0034-6659

Article publication date: 1 August 2000

Citation

Wincott, J. (2000), "The paper sack - food for thought", Nutrition & Food Science, Vol. 30 No. 4. https://doi.org/10.1108/nfs.2000.01730daf.001

Publisher

:

Emerald Group Publishing Limited

Copyright © 2000, MCB UP Limited


The paper sack - food for thought

The paper sack - food for thought

The big argument - paper versus plastic

The paper sack has been a traditional companion to the food industry since food packaging progressed to paper from the original hessian or jute sacks. Yet in recent years paper has itself often been usurped as a packaging medium by plastic - frequently purely on a cost basis. Are the days of the paper sack in the food industry numbered, or will the resilience of the paper sack win through against plastic in the end?

The Environmental and Technical Association for the Paper Sack Industry (ETAPS) has been running a campaign during the past 12 months pointing out, in a quite aggressive manner, the advantages that they claim for paper sacks in comparison with their plastic counterparts. The key arguments they have put forward are that paper sacks are better than plastic ones because:

  • Oil (the raw material for plastic) is a limited and precious resource that should be conserved. It has also been involved in many catastrophes in its production and transportation. Trees (the raw material for paper) are a renewable harvest and generally benign resource.

  • Paper has a greater opportunity for recycling than plastic which consequently ends up either in land fill or as wind-blown litter.

  • Many of the properties of paper sacks are better suited to the storage and transportation of food items than plastic; for example, paper sacks allow the contents to breathe, whereas plastic can cause condensation to the detriment of the product quality, and with potential hygiene considerations.

  • Paper contains far fewer controversial additives than plastic and so gives less cause for concern in the minds of the consumers.

It is necessary to look at each of these arguments in depth to see if the assertions in favour of paper sacks hold water.

Trees and oil - friend or foe?

Many years ago, the production of paper from trees caused significant amounts of pollution. However, since the mid-1970s, the European and Scandinavian paper industry has been involved in a massive operation to improve its processing, right through from the growth and husbandry of the basic forests, to the energy consumption and emissions at the mills. This has resulted in a dramatic reduction in the levels of emissions from the paper mills and greatly improved techniques in forest husbandry. A typical Swedish paper mill is Stora who by 1995 had reduced their COD[1] emissions to one tenth of the 1970 levels (Stora Environmental Report, 1997). Similarly KorsnÌs, another Swedish mill, had reduced their BOD[2] emissions in 1997 to less than the 1900 level in spite of increasing production tenfold (KorsnÌs Works and the Environment Audit, 1997). Much of this improvement is due to the introduction and adoption by the mills of ISO 14001 - the global environmental management standard. In the forest husbandry area of control, the Forestry Stewardship Council standard is the internationally recognised register of good forestry practices.

Paper sack manufacturers in the UK use paper from paper mills that operate a programme of forest husbandry and replanting that ensures that there is a constant increase in the number of trees available - a genuine sustainable resource.

Plastic sacks use fossil fuels (e.g. oil) as the raw material which is a non-renewable energy source that is rapidly being depleted. This oil will run out; in fact, as Ivanhoe says:

Unscientific reserve claims for political reasons may obscure the fact that most large, economic oil fields have been found, and permanent oil shock is inevitable early in the next century [2000] (Ivanhoe, 1995).

And yet the move from paper sacks to plastic has continued unabated for the last 20 years. The recent rises in oil prices and the knock-on effect on raw plastic costs were predicted in 1996:

compelling evidence points to a pending oil supply shortfall, possibly before 2000, which could trigger a third and permanent radical rise in oil prices (Campbell, 1996).

These effects all militate in favour of a sustainable resource, i.e. trees, which produce a product - paper - with a more stable price structure.

ETAPS maintain that during the complete product life-cycle, plastic sacks produce much more carbon dioxide, and consume more fossil fuels, than paper sacks. In the life-cycle analysis conducted by Ecobilan and Chalmers Industriteknik (summarised in The Industrial Paper Sack, an Environmentally Friendly Packaging [sic], 1996), the comparative results obtained for paper sacks versus plastic ones clearly showed that in the complete life cycle, and in the best case scenario for plastic, plastic sacks contribute over 12 times more carbon dioxide into the atmosphere than paper ones. The usage of non-renewable energy is also over eight times worse in the life cycle of plastic sacks than paper ones. The report concludes with these two points:

The overall environmental impact of paper sacks is less than that of polyethylene sacks and the difference seems significant. In fact, two elements are fundamental in analysing the environmental impact of the paper sack: it is manufactured from a renewable resource originating from cultivated forests; thanks to the phenomenon of photosynthesis, the impact of biomass CO2 emissions is nil.

Would a raw material that has the capacity to remove greenhouse gases from the atmosphere be beneficial? The aspect of carbon locking is one that is little understood outside the circle of people directly involved. The theory is simple - as a tree grows it converts carbon dioxide into carbon and stores it away in the wood. Younger trees convert carbon dioxide into wood more rapidly due to their heightened growth rate. When this tree is harvested, most of it is used as wood for the construction or furnishings industries, and all of the wood used in this way continues to lock away the carbon. The remainder of the trees (typically less than 10 per cent) is used in paper manufacture. This paper either is then recycled, or eventually may be burned in power generation. Even when burned, paper helps the carbon dioxide cycle by replacing a fossil fuel such as coal or oil. The carbon dioxide returned to the atmosphere from the paper is still a very small percentage of that originally removed in the growth phase of the tree. In more definitive terms:

Growing trees absorb carbon dioxide through photosynthesis, convert it to carbon and lock it away in the composition of wood. The timber frame in a house of 180 square metres stores around 7.5 tonnes of carbon (Between the Leaves, 1993).

Similarly, the use of modern forestry techniques results in much greater carbon absorption than just leaving mature forests to follow their natural life cycle:

Like all plant life, forests need carbon dioxide to survive. Absorption of carbon dioxide is highest when they are young, vigorous and growing. Mature forests are often in a state of equilibrium and their ability to absorb carbon dioxide is low. A continuous cycle of growth, harvesting and re-growth allows maximum absorption of carbon dioxide and reduces the concentration of greenhouse gases in the atmosphere (Between the Leaves, 1993).

Oil has also been involved in many terrifying ecological disasters in its extraction, transportation and processing (Table I). Many of these have resulted in long-term damage to the affected ecosystems, substantial loss of wildlife, and in the worst cases loss of human life as well. On the other hand, the danger to the environment from trees in their "natural" state is negligible. They do not spill, or pollute the environment.

Recycling - the detailed case

It is claimed by ETAPS that paper is the better packaging medium because it is easier to recover and recycle, it is more extensively recycled, and the public are involved in the recycling culture for paper. Looking in turn at each of these points it is possible to establish the reality behind these claims.

"Paper is easier to recycle" is based on the situation whereby the different categories of paper are still suitable for recycling in the same process. Plastic, however, comprises a diverse range of different chemical compounds, some of which are totally immiscible when melted down. This means that plastic needs careful sorting and grading before it is subjected to any form of recycling process. So, if the easy integration of product into the recycling stream is the key factor, then certainly paper has the edge by virtue of its simplicity. As stated by Mr Brian Smith, Chief Executive, Valuplast Ltd:

Plastic is not a single material but a rather complex family of materials. Whereas the recovery and recycling of traditional packaging materials is mature, the knowledge and infrastructure for plastics recovery is relatively in its infancy (Vantage, 1998).

"Paper is more extensively recycled" is undoubtedly true - figures published by the Department of the Environment, Transport and the Regions bear this out:

In 1997, 41 per cent of paper was recovered in the UK (DETR, 1999).

Looking at plastic the situation is very different:

It is estimated that there are 2.8 million tonnes of various types of plastic waste generated in the UK annually. Packaging currently accounts for approximately 60 per cent of this waste ... Plastics account for approximately one fifth of waste packaging materials; the split between domestic and industrial plastic packaging waste is assessed at 1.2 million tonnes domestic and 0.5m tonnes industrial. The main disposal route of waste plastics is currently landfill, with some incineration and recycling. It is estimated that 100,000 tonnes of plastic packaging were recycled in 1997, with 150,000 tonnes incinerated with energy recovery (DETR, 1999).

"The public are more involved in recycling paper" is a result of a number of factors:

  • the length of time that voluntary (i.e. before regulation made it compulsory) paper recycling has been in the public arena, also assisted by the newsprint industry's active involvement in recycling;

  • the local council schemes that already exist for paper recycling; and

  • the lack of consumer effort required in the preparation of paper for recycling.

Compared with plastic, where there are very few council run collection schemes (and where sorting is required before placing the product for recycling), the advantages of paper are clear. This is also highlighted in the report:

Traditionally, plastics have tended not to be recycled as the cost of recycling and decontamination have militated against the process (DETR, 1999).

The wind-blown litter aspect of plastic waste is an emotive reference to the common sight of plastic bags and sacks blowing around the countryside. With plastic being very durable, its lifespan in the form of litter is considerable - often a plastic bag can remain in the environment for many months, or even years, before it eventually succumbs to the elements. Obviously, the implication is that poor management of plastic by the end users results in a far greater problem than that caused by similar carelessness among paper users, paper having the advantage of being naturally degradable in such circumstances.

The other significant aspect of the waste v. recycling equation is the cost of disposing of waste packaging. Landfill sites become ever more expensive, the PRN[3] system is attempting to realistically cost the various elements of waste recovery and recycling, and the producer obligations are becoming ever more stringent. Coupled together these factors make a very compelling argument for the use of a readily recyclable or energy recoverable packaging material that does not contribute to the growth of the waste mountain that faces us in the future. Properties in use

ETAPS claim that paper sacks are better suited to many food applications than plastic. One property which is unique to paper is porosity. Paper sacks, while allowing the contents to breathe, provide a more satisfactory storage medium for many foodstuffs than plastic sacks. Certainly, a glance at the packs of potatoes and carrots on a supermarket shelf, with their plastic bags covered in condensation, is an indication that problems undoubtedly exist with this as a packaging material. And yet almost all of the major retailers use plastic for storing their vegetables. The most likely two reasons for this are: the cost of the plastic bags as against paper ones, and the ability of the customer to see the product through the package. However, in these times of supermarket quality warranties, and customer service, does seeing the product make that much difference? Is there a marketing opportunity for a retailer to "guarantee that their potatoes are perfect, or we will replace the whole pack for free", i.e. encourage the consumer to trust the retailer to have good enough quality control? Then, at least, the food in the opaque, breathable, paper sack will be in the best possible condition when it reaches the point of consumption.

Other performance factors in which paper claims to have the advantage include easier stacking and palletising (with less slip on the filled pallet), higher fill rates without the need for perforation, and better print quality. Additives

This is the area of most contention, where the consumer is constantly barraged with information and test results that seem to prove almost anything and nothing. ETAPS claims that the plastic bags and sacks used in food packaging are more likely to contain chemical additives than their paper equivalents. Given the contentious nature of this area of food handling, what are the facts behind these claims?

One of the key group of chemicals that causes concern to the consumer is phthalates - specifically those used in the manufacture of plastics. Phthalates are used primarily to impart the flexible characteristics that are so useful in plastic - without using these chemicals the plastic would revert to its "natural" state which is hard and brittle. Various claims have been made against phthalates including that they are oestrogen mimics, and that they are carcinogenic. The plastic industry vigorously denies these claims insisting that they are unsubstantiated, and they ran an advertising campaign claiming that phthalates were safe. However, after objections from various environmental pressure groups, the Advertising Standards Authority found that the advertisement was misleading and asked the advertisers not to repeat this claim. Specifically:

The Authority [Advertising Standards Authority] consulted the PVC Retail Working Group Report, in which a group of prominent scientists summarised and assessed the body of peer-reviewed research relevant to the environmental impact and health implications of PVC food packaging. The report explained that phthalates were widely distributed in the environment because of their widespread use and moderate resistance to breakdown. Because they were soluble in fat, environmental phthalates worked their way up the food-chain and have been found in high concentrations in human breast milk. The report confirmed that research had found phthalates to be weakly oestrogenic and in high concentrations they could mimic natural oestrogens (ASA Adjudications: Packaging and Industrial, 1998). Conclusion

So the claims made by ETAPS can be substantiated by research findings. But will this information have any impact on the decision makers in the food manufacturing and packaging industry? In all probability, cost is the most important factor in choosing the packaging material and, until the price of plastic rises to the point of making plastic sacks more expensive than paper ones, the market will probably still favour the cheap option.

However, the opportunity exists now for the more forward-sighted companies to take a lead in this very important area - the packaging decision. And, as the price of oil continues to rise, the argument will eventually undoubtedly turn to favour paper purely on a cost basis.

John WincottPartner, Jay 3 Productions, Fife, Scotland

Notes

  1. 1.

    COD (Chemical oxygen-consuming substances) is a measure of the quantity of oxygen needed for full degrading of organic material.

  2. 2.

    BOD (biological oxygen-consuming substances) is a measure of the level of aerobic organic substances.

  3. 3.

    PRN is the packaging recovery note - the system by which industry fulfils its obligations under the packaging waste regulations.

References

ASA Adjudications, Packing and Industrial (1998), concerning advertising material from the group comprising: The British Plastics Federation, London, The European Council of Vinyl Manufacturers, Brussels, and Packing and Industrial Films Association, Nottingham. Between the Leaves (1993), "Forests and the planet's future", DPI Forestry and the Department of Natural Resources in Queensland, Summer. Campbell, C.J. (1996), The Twenty-first Century. The World's Endowment of Conventional Oil and its Depletion, January. DETR (1999), A Way with Waste. A Draft Waste Strategy for England and Wales, Part Two, Department of the Environment, Transport and the Regions, 3 August. Ivanhoe, L.F. (1995), "Future world oil supplies: there is a finite limit", World Oil, October. KorsnÌs Works and the Environment Audit (1997), KorsnÌs AB, GÌvle, Sweden. Stora Environmental Report (1997), Stora Kopparbergs Bergslags Aktiebolag, Falun, Sweden. The Industrial Paper Sack, an Environmentally Friendly Packaging (1996), "The life cycle analysis of industrial paper sacks", Eurosac/Eurokraft, Paris/Stockholm. Vantage (1998), Plastic in Perspective, Vantage, Summer, p. 4 (quote by Mr Brian Smith, Chief Executive, Valuplast Ltd).