Memorandum submitted by Symphony Plastic
Technologies plc
DEGRADABLE PLASTIC
There is increasing activity by Government positively
to address the huge problems of litter and waste and a number
of important proposals (such as a Bag Tax and Waste Initiatives)
are currently under consideration. Whilst plastics are a significant
contributor to these problems, the arrival of degradable plastics
now provides an opportunity for legislators actively to encourage
their use and thereby mitigate the adverse effects traditionally
associated with plastic which has, until recently, been a virtually
indestructible material.
BACKGROUND
Plastic packaging is a very familiar component
of modern living—the material is used in all sorts of packaging
and household applications. Whilst the benefits of economic production
costs, light weight, strength, relative imperviousness to gas
and water, clarity, and printability are highly regarded, it is
the final disposal of used flexible plastics that causes problems.
The very properties that make plastic such a useful and economic
packaging medium become a major drawback when disposal is required.
However, current technological developments
in the flexible packaging industry have addressed these problems.
There are now a number of alternative methods of manufacturing
a plastic material that will degrade to a number of harmless elements—typically
water and carbon dioxide.
TYPES OF
DEGRADABLE PLASTIC
Starch-based
Some degradable plastic products are based on
starch derived from maize. These materials predominantly require
an active microbial environment such as landfill or composting
before they will degrade—some will totally degrade in such
an environment but others will only perforate, and the plastic
component will not degrade. Whilst using renewable ingredients
may seem attractive in principle, they do not offer the best way
forward
Aliphatic
Another method is through aliphatic polyesters
which are relatively expensive. In the same manner as starch,
they rely on microbial activity in compost or soil to degrade.
Oxo-degradable
The products mentioned above degrade by a process
of HYDRO-degradation, but the most useful and economic of the
new technologies produces plastic which degrades by a process
of OXO-degradation. This technology is based on a small amount
of pro-degradent additive (typically 3%) being introduced into
the conventional manufacturing process, thereby changing the behaviour
of the plastic This does not rely on microbes for the degradation
of the plastic, which starts immediately after manufacture and
will accelerate when exposed to heat, light or stress. This process
is irrevocable and continues until the material has reduced to
nothing more than CO2 and water. It does not therefore leave fragments
of petro-polymers in the soil.
It will also be consumed by bacteria and fungi
after the additive has reduced the molecular structure to a level
(sub 40,000 Daltons) that permits living micro-organisms access
to the carbon and hydrogen within. The material has then ceased
to be a plastic and has become a food source.
It can therefore be properly described as "biodegradable"
or even "omni-degradable."
Oxo-biodegradable products have the following
significant advantages over plastics produced from starch or other
agricultural products:
1. They biodegrade and can be composted but
they do not need to be buried in a compost heap or landfill in
order to degrade. They will degrade in a normal environment. This
is a very important factor in relation to litter, because a large
amount of plastic waste on land and at sea cannot be collected
and buried.
2. They are stronger and more versatile,
and can also be used for direct food contact, but they will degrade
as well or better.
3. They are much cheaper to produce.
4. They are thinner and use less material
to produce.
5. They can be made to be transparent so
that the food or other product within can be clearly seen.
6. Bags made from them do not leak.
7. Less energy is required to produce and
transport them.
8. It seems wrong to divert agricultural
resources away from food production when there is so much hunger
in the world, and to use fertilisers and pesticides unnecessarily.
The length of time it takes for the plastic
to degrade totally can be "programmed" at the time of
manufacture and can be as little as a few months or as much as
a few years. There is little or no additional cost involved in
products made with this technology.
Unlike PVC, the polymers from which oxo-biodegradable
plastics are made do not contain organo-chlorine. This is very
important.
FOSSIL RESOURCES
Oxo-biodegradable plastics are made from a by-product
of oil refining, and oil is a finite resource However, these by-products
are produced because the world needs fuels for engines, and would
be produced whether or not the by-product were used to make plastic
products.
It seems to us therefore that for at least the
next 25 years or so, until other fuels have been developed for
engines, it makes good environmental sense to use the by-product,
instead of wasting it by "flare-off" and using valuable
food crops to make plastic bags. Also, for the reasons mentioned
above, oxo-biodegradable products are in many respects more useful
than starch-based products.
As the labour, cost, and energy required to
produce the raw material for oxo-biodegradable plastics is going
to be incurred anyway in the production of fuels, it cannot properly
be attributed to oxo-biodegradable plastics in any life-cycle-assessment.
PRACTICAL ENVIRONMENTAL
BENEFITS OF
OXO-BIODEGRADABLE
PLASTICS
There are five arenas where oxo-biodegradable
plastic can have a major beneficial impact on the environment:
1. Litter
Discarded conventional plastics remain in the
environment for decades, and are often impossible to collect.
They block sewers and drains, they kill wildlife on land and in
the rivers and oceans, and they disfigure our streets, beaches
and countryside. oxo-biodegradable plastic on the other hand will
harmlessly fragment and degrade in a predetermined time to nothing
more than water, with a tiny amount of carbon dioxide.
Exposure to sunlight in a field would accelerate
the degradation and fragmentation of the plastic, but If oxo-biodegradable
bags were eaten by a cow, deer, turtle or other animal whilst
still intact, the temperature and bacteria present in the gut
would further accelerate the degradation process, unlike conventional
bags which would be more likely to cause a blockage which could
kill the animal.
The oxo-biodegradable bags would not adversely
affect the milk or meat.
To limit or discourage the availability of plastic
bags is not the whole answer as there are so many purposes for
which they are ideal.
Many people, especially those on low incomes
living alone, use carrier bags for the disposal of their dry and
wet kitchen waste. Paper bags are not suitable for this purpose
and many other purposes, and are heavier and more expensive.
Long-term re-usable shopping bags (Bags for
Life) are not the answer either, because shoppers do not always
go to the shop from home, where the re-usable bags would normally
be kept. The bags are much thicker and more expensive, and a large
number of them would be required to accommodate the weekly shopping
for an average family. They are not hygienic unless cleaned after
use, and those bags themselves when discarded—which is usually
after only a few months—become a very durable form of litter.
Ireland introduced a tax on plastic carrier
bags in March 2002. It has had a significant effect but still
a very large number of conventional plastic carrier bags are being
supplied at shops and supermarkets. The Irish Government missed
the opportunity to encourage or require a move to degradability.
Unfortunately, there will always be people who
will deliberately or carelessly discard their plastic waste. Is
it not better that the discarded plastic should be biodegradable?
2. Composting
Organic waste can be put into oxo-biodegradable
plastic sacks in homes, restaurants, hospitals, etc. and put straight
into the composting plant without the messy and expensive business
of emptying the sacks and disposing of them separately. Disease
transmission by flies and rats, and handling hazards to humans
are effectively minimalised by the use of such sacks.
The practical experience of Erewash Borough
Council's municipal composting scheme in Britain has been positive,
and more than 50 British local authorities have bought oxo-biodegradable
bags for composting.
The resulting compost is a valuable resource
for farmers and growers, and since oxo-biodegradable plastic releases
its carbon slowly, it produces high quality compost.
The growing requirement to segregate "green"
waste is assisted by the use of oxo-biodegradable/compostable
bags that can safely be assimilated into the green waste stream.
3. Landfill
For the reasons described above, much more waste
can be safely and conveniently composted for use instead of being
sent to landfill and lost. Oxo-biodegradable plastic can also
be recycled or incinerated instead of being sent to landfill.
Oxo-biodegradable plastic will continue to degrade if put into
landfill with brick, concrete, metal, conventional plastic, and
other non-organic materials, but starch-based plastics will degrade
only in an active bacterial environment.
At present a six to eight inch layer of earth
has to be spread over the waste in a landfill at the end of each
day's work. This is very expensive to do, and it also uses up
a high proportion of the available space in the landfill pit.
However, oxo-biodegradable plastic sheeting can now be used as
Daily Landfill Covers instead of earth, to cover the waste, and
less fuel is burned by the machines employed.
4. Agriculture and Horticulture
In addition to compost mentioned at two above,
oxo-biodegradable plastic has other useful applications. For many
years now, farmers and growers have used plastic sheets to protect
their crops and to inhibit weeds. They have also constructed tunnels
over the growing plants out of plastic sheets.
This has worked well, but after the crop has
been harvested many thousands of square kilometres of plastic
have to be removed and disposed of. This is a very expensive process,
and creates huge quantities of contaminated plastic waste. Oxo-biodegradable
plastic sheets can however be programmed at manufacture to degrade
soon after the harvest. The fragments can then be ploughed into
the soil where they complete the biodegradation process and become
a source of carbon for next year's plants.
Eco-toxicity tests have demonstrated that they
produce no immediate, or cumulative, adverse effects on the soil,
whether from the plastic itself or from peroxidants, plasticisers,
surfactants, pigments, metals or lubricants. The major elements
of these latter materials are naturally bio-degradable. The traces
remaining after degradation are in such minor parts per million
(in some cases, per billion) that no harmful effects will occur.
These materials can also be present in starch-based products.
5. Recycling
Oxo-biodegradable plastics are entirely compatible
with the principles of recycling. After cleansing, separation
and re-extrusion the degradation process is arrested, and the
recycled plastic reverts to the properties of conventional plastics.
Interestingly, as a further option, the additive can be added
to recyclate and will cause that to degrade in turn if that is
the required outcome.
Recycling in general has an important role to
play in the overall management of resources but will never cover
all plastic packaging. The UK uses 1.5 million tonnes of polyethylene
packaging a year, yet there is only the capacity to deal with
250,000 tonnes of it. As only a small proportion of waste is recycled,
the use of oxo-biodegradable plastics allows the better management
of that part which is not recycled.
It should be added that as virgin feedstock
is so inexpensive, recycling of plastics is not practical without
subsidies from public funds which could be put to better uses.
Recycled plastics are in any event limited to use in heavy, long-life
items such as garden furniture rather than as replacement bags,
and cannot be used for food contact.
It is not suggested that the waste hierarchy
needs fundamental change, but it should be recognised that mechanical
recycling is of limited use in the case of plastics. It is better
to switch to oxo-biodegradable plastics which can be recycled
by composting.
DEFINITIONS OF
DEGRADABILITY
The only European standard as yet which attempts
to define and measure degradability is EN 13432. However, the
tests prescribed by this standard relate only to plastics which
degrade by a process of HYDRO-degradation.
Plastic which degrades by a process of OXO-degradation
does not meet the EN 13432 tests because it does not emit enough
carbon dioxide! Even a leaf would fail this test for the same
reason and could not therefore not be described as compostable
for the purposes of EN 13432. Accordingly, any legislation which
defines biodegradability by reference to EN 13432 will deprive
the consumer for no good reason of a whole range of products which
degrade by oxo-degradation.
Further, products which comply with EN13432
cannot be regarded as being "recoverable" by composting,
and should strictly be defined as "disposable" since
the nutritional value of the carbon in the polymer is substantially
lost by emission to atmosphere. The higher volumes of CO2 emitted
from hydro-degradable plastics create an unnecessary environmental
burden. By contrast in oxo-degradation the carbon is substantially
recycled as a nutrient in the soil.
Although the 1994 Waste Packaging Directive
does not itself require compliance with EN 13432 there is a reluctance
in the marketplace to accept products as biodegradable unless
they can be certified as complying with a European Standard. A
new standard is therefore urgently needed to cover oxo-biodegradable
plastic, and plastic carrier bags should not be brought within
the Waste Packaging Directive until the new standard is in force.
The British Standards Institute proposed to
CEN (the European Standards organisation) in 2002 a new standard
(N 0123) which would apply to oxo-degradation. It is presently
being considered within CEN and will be discussed by WG2 in February
2003
THE ROLE
OF GOVERNMENT
There will remain a need for shops and supermarkets
to supply plastic carrier bags and other plastic products to their
customers, but such is the inertia in the retail industry that
they will continue to supply conventional plastics unless Government
gives an incentive to use the more environment-friendly oxo-biodegradable
alternative, exactly as the UK Government did a few years ago
with unleaded petrol.
If governments wish to introduce a tax on plastic
bags it should apply to all kinds of conventional plastic products
for which there is an available oxo-biodegradable alternative,
not just carrier bags, but there should be a lower tax or no tax
at all, on oxo-biodegradable plastic. Even if a single tax rate
were appropriate, the opportunity exists to require the phasing-out
of conventional plastic for all products for which oxo-biodegradable
plastics are a suitable and available option.
Degradable plastics should also be treated more
favourably than conventional plastics for the purposes of the
Producer Responsibility regulations.
The UK Chancellor of the Exchequer announced
on 27 November 2002 plans to give council tax discounts to people
who recycle or compost their household refuse. They should therefore
be using oxo-biodegradable sacks for their organic refuse intended
for composting.
The Chancellor further announced a steep rise
in the landfill tax. This makes it even more important to send
organic refuse for composting in oxo-biodegradable sacks, instead
of to landfill.
The Chancellor also announced a vat cut on products
made from recycled paper and glass, but in order to encourage
the use of oxo-biodegradable plastics there should also be a vat
cut on products made from them.
EU Environment Commissioner, Margot Wallstrom,
said, in a letter to the Irish MEP Avril Doyle on 18 February
2002 that "it would be consistent with the spirit of Community
environment policy and legislation if a member state applying
a plastic bag tax were to decide to adopt a more beneficial tax
rate in relation to biodegradable carrier bags."
Symphony Plastic Technologies plc
22 January 2003
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