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Why do we need
oxo-biodegradable plastic and Reverte®?
Thousands of tons of plastic
waste enter the world's environment every day, and will remain
there for hundreds of years, unless collected for incineration.
The oxo-biodegradable process provides an alternative to
prohibiting plastic by providing the most effective method of
plastic disposal without damaging the environment. The oil and
natural gas based Reverte® has
several advantages over the other vegetable based biodegradable option,
A very small amount of Reverte® is
put into the manufacturing process. This breaks the molecular chains
in the polymer, and at the end of its useful life the product falls
apart. The plastic does not just fragment, but will be consumed by
bacteria and fungi after the additive has reduced the molecular
weight to a level which permits micro-organisms access to the carbon
Does Reverte® really
biodegrade, or does it just fragment?
Yes! Once the molecular weight
of the film has reduced sufficiently it is
available for biodigestion. Assuming there is
sufficient viable flora and fauna the low
molecular weight species will be mineralised or
When the material has reached the fragmentation
stage it is no longer a plastic, and is "biodegradable" in the same
way as nature's wastes such as straw and twigs. The process
continues until the material has biodegraded to nothing more than
CO2, water, and humus, and it does not leave fragments of
petro-polymers in the soil.
How quickly does
An important advantage of oxo-biodegradable
plastic is that it can be programmed to degrade in whatever
timescale is required. The average useful life of a carrier bag
is about 18 months, but shorter or longer times are possible.
During that time bags are often re-used for shopping or for use
as bin-liners etc. Heat and light will accelerate the process,
but they are not essential.
Very little, because the additive represents
less than 3% of the product, and because the products can be
made with the same machines and workforce as ordinary plastic.
Won't it put
existing factories out of business, with loss of jobs?
No, because customers can still
use the factories which supply them with ordinary plastic
What types of
biodegradable plastics exist?
The two main types are oxo-biodegradable and
hydro-biodegradable. In both cases degradation begins with a
chemical process (oxidation or hydrolysis), followed by a biological
process. Both types emit CO2 as they degrade, but while oxo-biodegradables
are oil or natural gas-based, hydro-biodegradables are usually made
from corn or other starchy vegetables and can emit methane. Both
types are compostable, but only oxo-biodegradable can be
are available in oxo-biodegradable plastic?
Among the products available:
Carrier bags or "shopper-bags" which
consumers use to take away their purchases from the shop
Refuse sacks, which consumers buy in
rolls at the shop, and use for disposal of their ordinary
Aprons, for the protection of garments,
in the home, hospitals, restaurants, workshops etc.
Bags to contain dog feces collected in
parks, gardens, etc.
Plastic sheeting for a variety of
applications in agriculture and horticulture.
Plastic film for wrapping newspapers and
Frozen food bags
Wrappers for cigarette packets
Shrink-wrap and pallet-wrap
Rigid products such as bottles and cups
What are the
differences between the Reverte® oxo-biodegradable and
hydro-biodegradable plastic, and advantages of the oxo-biodegradable
|Made from a
by-product of oil or natural gas
||Usually made from vegetable
products such as starch
|Can be recycled as part of
a normal plastic waste-stream
||Damages recyclate unless
extracted from feedstock
|Can be made from recyclate
||Cannot be made from
|Time to degrade can be set
||Cannot be controlled
|Emits CO2 slowly while
||Emits CO2 rapidly while
degrading. As 90% of it must convert to CO2 within 180 days
in order to comply with the Standards for compostable plasitc, these plastics contribute to climate change but do
not improve the soil.
|Inert deep in landfill
||Emits methane deep in
|Can use same machinery and
workforce as for conventional plastic
||Needs special machinery and
|Suitable for use in
||Usually not suitable
||Compostable (but not for
|Little or no additional cost
||Four or five times more
expensive than conventional plastic
|Same strength as
||Weaker than conventional
plastic (unless mixed with oil-based plastic)
|Same weight as conventional
||Thicker and heavier
||Prone to leakage
|Degrades anywhere on land
||Degrades only in
|No genetically modified
||Possibility of GM
|Safe for food contact
||Safe for food contact
|No PCB's Organo-chlorines,
or "heavy metals"
||No PCB's Organo-chlorines,
or "heavy metals"
|Can be incinerated with
||Can be incinerated, but
lower calorific value
|Production uses no
fertilisers, pesticides or water
||Production uses fertilisers,
pesticides and water
|No limit on availability of
||Limited availability of
|Demand for oxo-biodegradable
plastics does not drive up cost of fuel for vehicles
hydro-biodegradable plastics drives up price of human and
Isn't it better to recycle than to let it
Yes, and one of the benefits of
oxo-biodegradable plastic is that it can be recycled as part of
a normal plastic waste stream. However, if the plastic is not
collected it cannot be recycled, so it needs to biodegrade
instead of accumulating in the environment.
In some countries incineration is popular,
and modern equipment is in place. Oxo-biodegradable plastic can
be incinerated with energy recovery in the same way as
conventional plastic, and has a higher calorific value than the
compost? Can it be
No! Compostability is defined
under ASTM 6400 and EN 13432, these are
industrial processes which require very rapid
biodegradation under high heat and high moisture
While oxo-biodegradable plastic does not degrade
quickly in low temperature "windrow" composting, it is
suitable for "in-vessel" composting at the higher temperatures
required by the new EU animal by-products regulations. Indeed it
is likely that windrow composting will soon have to be phased
What happens to Reverte® in a landfill?
Oxo-biodegradable plastics fragment and
partially biodegrade to CO2 and water in the parts of the
landfill where oxygen is present, but the residues are
completely inert deeper in the landfill in the absence of
oxygen. They do not emit any significant amounts of methane. By
contrast, hydro-biodegradable (starch-based) plastics will
degrade and emit CO2 in a landfill if there is enough microbial
activity. However, in the depths of a landfill, in the absence
of air, hydro-biodegradable plastics generate copious quantities
of methane, which is a powerful greenhouse gas.
Does oxo-biodegradable plastic contain "heavy metals"?
No. It contains transition metal ions of
cobalt or iron or manganese, which are trace elements required
in the human diet. They should not be confused with toxic heavy
metals such as lead, mercury, cadmium and chromium, which are
never used in oxo-biodegradable plastics.
Aren't oxo-biodegradable plastics made from oil?
Yes. Oxo-biodegradable plastics are
currently made from a by-product of oil or natural gas. These
are of course finite resources, but the by-product arises
because the world needs fuels, and would arise whether or not
the by-product were used to make plastic goods.
Until other fuels and lubricants have been developed for
engines, it makes good environmental sense to use the
by-product, instead of wasting it by "flare-off" at the refinery
and using scarce agricultural resources to make plastics. In
fact plastics could reduce the amount of oil and gas imported
because after their useful life they can be incinerated to
release the stored energy, which can be used to generate
electricity or to heat buildings.
Recently, interest has been shown in manufacturing sugar-derived
polyethylenes. These, like oil-derived PE, are not
biodegradable, but they can be made oxo-biodegradable in the
same way as the latter, by the addition of a pro-degradant
But aren't the
hydro-biodegradable plastics renewable?
No because the process of making them from
crops is itself a significant user of fossil-fuel energy and a
producer therefore of greenhouse gases. Fossil fuels are burned
in the machines used to clear and cultivate the land, and in the
manufacture and transport of fertilisers and pesticides and in
transporting the crop itself. Energy is also used by the
autoclaves used to ferment and polymerise material synthesised
from biochemically produced intermediates (e.g. polylactic acid
from carbohydrates etc). When the material biodegrades it emits
CO2 and methane, so the total fossil fuels used and greenhouse
gases emitted are more than for conventional or oxo-biodegradable
Hydro-biodegradables are sometimes described
as made from "non-food" crops, but are in fact usually made from
food crops, and drive up the price of human and animal food. In
June 2009 Germany's Institute for Energy and Environmental
Research concluded that oil-based plastics, especially if
recycled, have a better Life-cycle Analysis than compostable
Does Reverte® leave
any harmful residues?
No. Oxo-biodegradable plastic
passes all the usual ecotoxicity tests, including seed
germination, plant growth and organism survival (daphnia,
earthworms) tests carried out in accordance with international
Are components deliberately and
The argument that oxo-biodegradable
plastics are undesirable because their components are designed
to be deliberately and totally lost is a fallacy, because if
people want to incinerate with heat recovery, or mechanically
recycle them, or compost them in-vessel, or re-use them, then
that's OK, and they cost very little if anything more than
conventional products. The key question is what happens to the
plastic that is not collected, and gets into the environment as
In any event, oxo-biodegradable
plastics are not "deliberately and totally lost" even if they
degrade in the environment, because biodegradation on land is a
source of plant nutrients, just as is straw, grass, leaves etc.
By contrast, hydro-biodegradable plastics are "deliberately and
totally lost" because the applicable international standards
require them to convert to CO2 gas within 180 days.
Degradable plastic bags have
been supplied by supermarkets for more than four years, but
there is no evidence that people dispose more carelessly of them
(whether oxo or hydro biodegradable) and they have not been
encouraged to do so. But suppose for the sake of argument that
10% more were discarded. If 1,000 conventional and 1,100 oxo-biodegradable
bags were left uncollected in the environment, 1,000
conventional bags would remain in the rivers, streets and fields
for decades, but none of the oxo-biodegradable bags would be
left at the end of the short life programmed into them at
manufacture. There will always be people who will deliberately
or accidentally discard their plastic waste. What will happen to
all the plastic waste that will not be recycled or will not be
incinerated, and instead will litter the countryside - would it
not be better if the discarded plastic were all oxo-biodegradable?
Is Reverte® safe for
Yes. Oxo-biodegradable plastic has
been certified by RAPRA Technology Analytical Laboratories as safe
for long-term contact with any food type at temperatures up to 40°C.
RAPRA is accredited by the United Kingdom accreditation authorities
as meeting the requirements of International Standards Organisation
norm no. 17025. It is also certified as compliant with FDA
requirements in the US.
Can Reverte® be marketed as biodegradable or
On 8th April 2010 the
Advertising Standards Authority of South Africa ruled that bread
bags made with oxo-biodegradable plastic can be advertised as
The current EU Standard for
composting (EN13432) is not appropriate for testing oxo-biodegradable
plastic. However the EU Packaging Waste Directive does NOT
require that when a packaging product is marketed as
"degradable" or "compostable" conformity with the Directive must
be assessed by reference to EN13432. The Directive provides that
conformity with its essential requirements may be presumed if EN
13432 is complied with, but it does not exclude proof of
conformity by other evidence, such as a report from a reputable
body. Indeed Annex Z of EN13432 itself says that it provides
only one means of conforming with the essential requirements.
Does Reverte® leave harmful residues?
No! Reverte® has been used for
many years in agricultural mulch film
applications, where the soil residues have been
independently evaluated and crop germination and
yields have been monitored. In addition many
customers have put Reverte® through the ASTM
6954 test protocol which has a specific soil
toxicity component (Tier 3).
Do Reverte® treated films
Yes! Reverte® was formulated
with the reduction of litter in mind, the
material commences breakdown once film is
discarded into the environment and rapidly
fragments into biodigestable constituents. At
this point the material is no longer a littering
hazard. Then if in a suitable environment the
material will biodegrade to leave water, biomass
Isn't it better to use paper bags?
No. 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.
When they degrade they emit methane and carbon dioxide.
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. It would take at least seven times the
number of trucks to deliver the same number of bags, creating
seven times more transport pollution and road congestion.
Also, because paper bags are
not as strong as plastic, people may use two or three bags
inside each other. Paper bags cannot normally be re-used, and
will disintegrate if wet.
Isn't it better to use durable re-usable
No. Long-term re-usable shopping bags are
not the answer. They 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
each use. Whilst sometimes called "Bags for Life" they have a
limited life, depending on the treatment they receive, and
become a very durable problem when discarded.
Shoppers do not always go to the shop from home, where the
re-usable bags would normally be kept, and consumers are
unlikely to have a re-usable bag with them when buying on
impulse items such as clothing, groceries, CDs, magazines,
stationery etc. However, for those who believe in long-term
re-usable bags, they can be made from extended-life oxo-biodegradable
plastic and will last for 3-5 years.
What national or international standards
Oxo-biodegradable plastic can
be tested according to American Standard ASTM D6954-04 for
Plastics that Degrade in the Environment by a Combination of
Oxidation and Biodegradation. Until recently there was no
standard in Europe designed to test oxo-biodegradable plastic.
However, In July 2007 the French Standards organisation, AFNOR,
published XP T 54-980, which is a Standard for oxo-biodegradable
plastics in agriculture.
A draft standard 8472 capable
of measuring oxo-biodegradation is being developed by the
British Standards Institution. European standard EN 13432
applies only to plastic packaging, and was written before oxo-biodegradable
plastics became popular. It is not appropriate for testing oxo-biodegradable
plastics because it is based on measuring the emission of carbon
dioxide during degradation. Hydro-biodegradable plastic is
compliant with EN 13432, precisely because it emits CO2 (a
greenhouse gas) at a high rate. Another unsatisfactory feature
of EN 13432 is that it requires almost complete conversion of
the carbon in the plastic to CO2, thus depriving the resulting
compost of carbon, which is needed for plant growth, and wasting
it by emission to atmosphere.
Conversion of organic materials
to CO2 at a rapid rate during the composting process is not
"recovery" as required by the European Directive on Packaging
and Packaging Waste (94/62/EC as amended), and should not be
part of a standard for composting. Nature's lignocellulosic
wastes do not behave in this way, and if they did the products
would have little value as soil improvers and fertilisers,
having lost most of their carbon.
If a leaf were subjected to the
CO2 emission tests included in EN13432 it would not be
considered biodegradable or compostable! Packaging made from oxo-biodegradable
plastic complies with para. 3(a), (b) and (d) of Annex II of the
European Parliament and Council Directive 94/62/EC (as amended)
on Packaging and Packaging Waste. This Annex specifies the
essential requirements for the composition, and the reusable and
recoverable, including recyclable, nature of packaging.
satisfies para. 3(a) because it can be recycled. It satisfies
para. 3(b) because it can be incinerated. It satisfies para.
3(d) because it is capable of undergoing physical, chemical,
thermal or biological decomposition such that most of the
finished compost ultimately decomposes into carbon dioxide,
biomass and water.