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Busting the myths around biodegradable plastics

Biodegradable plastics have been debated in different media and fora but there is more confusion than clarity on the facts. In the light of the ban on PET in pharmaceutical packaging for certain patient categories, sustainability activist Pranay Kumar, Chief Environment Officer, Vasudhaecofriends Projects clears the air on some of the issues and makes the case for products like Ecopure, which increase the biodegradability of plastics, making it more ecofriendly

Biodegradable plastics have been debated in different media and fora but there is more confusion than clarity on the facts. In the light of the ban on PET in pharmaceutical packaging for certain patient categories, sustainability activist Pranay Kumar, Chief Environment Officer, Vasudhaecofriends Projects clears the air on some of the issues and makes the case for products like Ecopure, which increase the biodegradability of plastics, making it more ecofriendly

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Pranay Kumar

A lot of debate has been generated in different media and fora on biodegradable plastics, bioplastics, standards, methodologies and their applications. The Ministry of Environment & Forests’ notification on plastic (waste) management, 2011, gutkha plastic packaging ban and recent intervention by the honourable Supreme Court of India on Karuna society’s plea for banning plastic bags have made it necessary to clear the air on the technologies, sustainability of each category of degradable plastic, application and legalities.

Overview

In early and mid 20th century, as the world searched for a light, flexible, strong and inert material for packaging of different products from machines to cosmetics, from water to milk, from wires to pipes, plastic proved its worth.

Some advantages of plastics: Versatile, non harmful to many types of food, flexibility in shape and forms; films to highly rigid structures, ability to withstand very high and very low temperatures and pressures, optical properties ranges from completely opaque to transparent like water, usage in research labs with highly corrosive chemicals and even making rocket nozzles.

Consider the facts about plastics: Plastic encases about 53 per cent of products we buy; it only makes up 20 per cent by weight of the packaging we consume. In comparison, glass as a packaging material also accounts for 20 per cent of the packaging we consume by weight, but only 10 per cent of the goods we buy. And in the packaging equation, weight is the main issue because the heavier something is, the more energy you expend moving it around!

Paper and recycled paper is perceived to be ‘ecofriendly.’ This author’s research suggests nothing can be far from truth. Paper and recycled paper (except for handmade paper) have high energy, water and carbon footprint 1. Making of paper is a highly water intensive process which pollutes the environment, besides cutting of millions of trees.

India as a country has been able to bring in ‘white’ (milk) and gold (edible oil) revolutions due to plastic. 50 per cent of India’s food is wasted2 due to lack of proper storage and packaging. Plastic packaging can save more than 25 per cent of the food. Despite of these advantages plastic has been made a villain in eyes of common citizens and the courts.

One of the biggest advantages of polymers, non degradability emerged as one of its biggest disadvantages. As a result of exponential in population, rise in standards of living and excessive consumerism {without a sense of responsibility towards the environment and other living species} plastic, especially polyolefin films and sheets have emerged as an environmental threat.

But we should ask ourselves, is plastic to be blamed or we should be responsible for its indiscriminate use? Under fundamental duty of the Constitution we, the citizens of India are responsible for our environment. After all plastic does not decide to litter itself!

Biodegradable plastics have a potential to become one of the best solutions for plastic waste management, especially for end of life solutions and plastic products which cannot be recycled or reused. Yet biodegradability cannot and should not be used an excuse for overuse/ littering.

Terminologies and technologies for degradability

Before we describe the technologies let’s understand the terminologies according to international standards and methodologies.

Standards are specifications set by recognised international/ national agencies, like ISO (international), ASTM (American), CEN (European), DIN (German), OECD and JIS (Japan) under which degradability parameters are defined.

Methodologies are defined procedures/ processes to determine a particular result. It should be noted that same standard can be determined through different procedures like standards ISO 14855/ASTM D 6400 can be determined either through ASTM 5338 or any other EU/ Japanese/National standards.

In India there is a lot of confusion between standards and methodologies. Terms such as biodegradable, compostable, degradable, photodegradable, oxodegradable have added to the confusion in India.

Terminologies for degradation in context of polymers/ plastics

Biodegradable: Simply speaking, biodegradable means degradable into biomass and gases (like CO2 and CH4) in presence (aerobic) or absence (anaerobic) oxygen because of action of microbes (mostly fungi and bacteria like actinomycetes). These are mostly made up from petroleum resources. Companies like BioTec Environmental manufacture the biodegradable additives.

Bioplastics: Partially or fully made up of starch/ polysaccharides/ aliphatic polyesters, either natural or synthetic and mostly aerobically biodegradable.

These can be subdivided into PLA (Poly-lactides), PHA (Polyhydroxyalkanoates), PHB (polyhydroxybutyrate), PCL (poly e-caprolactone) and PVOH (Polyvinyl alcohol).

Starch (polysaccharides) PHA and PHB are naturally occurring, while PLA, PCL, PVOH, PCL are synthetic. These are mostly derived from plants’ sources and even food crop sources (like corn or potato). MNCs like Novamont and Dow Cargill manufactures these.

Oxodegradable/ Oxo-biodegradable: Degradable/ fragmentable in presence of oxygen. [Oxodegradable has been declassified as non biodegradable recently by UK’s department of food and environment2, EU bioplastics Council* and Nature magazine3]. (More clarification follows in the section below.)

Photodegradable: Degradable into invisible pieces by action of the sun’s light and the sun’s heat. Photodegradable mostly contains heavy metals as additives, which attains higher excitation state due to high energy levels and break the polymer chain. But invisibles pieces remain in the environment.

Biodegradability: In 1992, an international workshop called Towards Common Ground – Meeting Summary of the International Workshop on Biodegradability, Annapolis, MD, US was organised to bring together experts from around the world to achieve areas of agreement on definitions, standards and testing methodologies. Participants came from manufacturers, legislative authorities, testing laboratories, environmentalists and standardisation organisations in Europe, US and Japan. Since this fruitful meeting, there is a general agreement concerning the following key points:

  • For all practical purposes of applying a definition, material manufactured to be biodegradable must relate to a specific disposal pathway such as composting, sewage treatment, denitrification, or anaerobic sludge treatment.
  • The rate of degradation of a material manufactured to be biodegradable has to be consistent with the disposal method and other components of the pathway into which it is introduced, such that accumulation is controlled.
  • The ultimate end products of aerobic biodegradation of a material manufactured to be biodegradable are carbon dioxide, water and minerals and that the intermediate products include biomass and humic materials.
  • Materials must biodegrade safely and not negatively impact on the disposal process or the use of the end product of the disposal.

Aerobic biodegradation:

  • CPOLYMER + O2 ® CO2 + H2O + CRESIDUE + CBIOMASS

Anaerobic biodegradation:

  • CPOLYMER ® CO2 + CH4 + H2O + CRESIDUE + CBIOMASS

Microbiological degradation can take place through the action of enzymes or by products (such as acids and peroxides) secreted by microorganisms (bacteria, yeasts, fungi, etc). Also macro-organisms can eat and, sometimes, digest polymers and cause mechanical, chemical or enzymic ageing. It has been established that microbial biodegradation occurs mostly in two steps.

Occurrence of biodegradation

Two key steps occur in the microbial polymer degradation process: first, a depolymerisation or chain cleavage step, and second, mineralisation.

The first step normally occurs outside the organism due to the size of the polymer chain and the insoluble nature of many of the polymers. Extracellular enzymes are responsible for this step, acting either endo (random cleavage on the internal linkages of the polymer chains) or exo (sequential cleavage on the terminal monomer units in the main chain).

Once sufficiently small size oligomeric or monomeric fragments are formed, they are transported into the cell where they are mineralised. At this stage the cell usually derives metabolic energy from the mineralisation process. The products of this process, apart from adenosine triphosphate (ATP), are gases, (e.g., CO2, CH4, N2, H2), water, salts and minerals, and biomass.

Many variations of this general view of the biodegradation process can occur, depending on the polymer, the organisms, and the environment. Nevertheless, there will always be, at one stage or another, the involvement of enzymes. (For a detailed explanation kindly contact the author.)

Compostability and biodegradability:

Compostability is biodegradability under controlled (read man made) conditions, in a specified time period. Aerobic degradation is the main form of degradation here.

Biodegradability is a wider term implying degradation in aerobic and/ or anaerobic conditions anywhere, whether manmade or natural not necessarily bounded by time.

The practical aspects of the above two terms have wider implications.

Biodegradability occurs practically everywhere, especially in landfills, heavy sewage sludge conditions or any natural or man made conditions suitable for optimal microbial activity. Microbes have used for decades to clean oil spills so why not plastics ( a derivative of petroleum ). By the way, a sample of soil can contain depending on the location, at least 2000 genres of bacteria. In our country, India with limited land resources and no developed systems of disposal biodegradability, hence biodegradable plastics makes huge sense. Also our landfills are wet, which is more conducive to biodegradation. Landfills have anaerobic environment {except for the top layer}, which is suitable for anaerobic biodegradation. Evidences of newspaper/ cellulosic material being partially or practically non-degraded, even after two decades exists in the world (and can be found on Internet) so think how a bioplastics can degrade in a landfill!

Composting/ industrial composting on the other hand requires industrial size compost facilities, where conditions have to be managed by man. [Composting here should not be confused with what we do with our kitchen waste at the back of the garden]. Hardly a few industrial composting exists (as defined by standards) in the US and Canada, where land is in ample supply.

Plastics biodegrade under two key steps:

  • Long polymer chain cut at the carbon-carbon bonds – by heat, moisture, enzymes, or other conditions depending on the polymer.
  • Shorter carbon chains pass through the cell walls of the microbes and are used as energy source.

Biodegradation: When the carbon chains are used as food source and converted into water, biomass, CO2 or methane. (Source: DuPont)

Comparison between different degradable plastics

Bioplastics: Bioplastics are of two types. One made fully from plant based starch resources and other where starch/cellulosic content is used as fillers.

Applications: Mainly carry and compost bags.

Advantage (claimed): Ecofriendly as made from natural resources.
Disadvantages: Shelf life is six to nine months, change in manufacturing processes and machines. Bioplastics are at least three to five times more expensive than oxodegradable or biodegradable plastics.

PLA cannot withstand high heat.

PLA also takes 30 per cent more oil to produce than plastic itself. PLA requires 56 megajoules/ kg of oil; PET requires 37 megajoules/kg of oil.

Degradation period: Six months to one year in aerobic conditions

Degradation process: Microbial, aerobic

Reality: Bioplastics made of PLA (most prevalent) requires lots of corn for starch-based plastic. It’s weak and brittle and is said to impart off taste to food it carries. It is very expensive too.

One starch-based biodegradable plant was opened with much fanfare in Kashmir by the Chief Minister, but it shut down within a year, due to poor qualities of the products.

Diversion of food crop to make plastic is unsustainable. To illustrate an example if all of the disposable plastic products in the world were made out of corn, 150,000,000 tonne of corn would be used to make plastic. Prices for corn would rise dramatically, and third world hunger would increase even more dramatically. There are currently 1,400,000,000 hungry people in the third world, says the UN.

Photodegradable degrades only action of light, specifically sunlight. It is brittle and expensive and they can be only used in bags with short shelf life. It has already become unacceptable to the market, so further mention is irrelevant.

Biodegradable plastics: Made of petroleum derivatives with addition of additives.
Advantages: No change in manufacturing process, Shelf life — Unlimited
Disadvantages: Using petroleum derivatives
Applications: Bags, bottles, films, non woven pp bags, shoe soles, car body and white goods’ parts and many others.
Degradation: Aerobic and anaerobic degradation under ASTM 5338 and ASTM 5511-11
Degradation period: Nine months to three years depending on type and thickness of polymer
Special mention-Plant bottle: Plant Bottle by Coca Cola is old wine a different bottle. It derives certain percentage of plastic/ bottle from plant sources. Firstly it remains non-degradable as it is still a non degradable plastic product; secondly it is unsustainable as it derives the raw material from plants. What was the logic of creating it is beyond comprehension.

Oxo plastics are fragmetable (fragment into small invisible pieces by action of oxygen and sunlight ) , not degradable. It has been banned by EU Parliament.

Applications: Mostly LDPE Bags. Claims of usage in PET bottles have not been authenticated. [Our company, Vasudhaecofriends’ interactions with many FMCG and manufacturing companies reveal that they have not used oxodegradable for film and bottle applications after trials due to its low shelf life and film properties].
Advantages: Inexpensive.
Disadvantage: Shelf life of six months to one year and contains heavy metals.
Degradation period: Unverified for landfill.
Degradation: Oxidation through oxygen and sunlight.
Reality: Though used by many companies and countries in application such as shopping and garbage bags, oxodegradable has been termed as non biodegradable by DEFRA, UK Government in 2010*. The same have been published by EU Bioplastics Council. Nature magazine published an online article on April 21, 2011 citing DEFRA report.

The DEFRA report mentioned, “These plastics should not be composted, as their breakdown fragments will ruin the resulting compost. But neither can such materials be incorporated into traditional plastics recycling as the same additives that encourage the break-up of the original material will degrade the recycled material produced.”

It further added, “Both of these options make the ‘degradable’ property of oxo-degradable plastics irrelevant.” Noreen Thomas, a materials researcher at Loughborough University, UK and one of the authors of the DEFRA report concluded, “There is no benefit to the environment of oxo-degradable plastics.”

Vasudha’s biodegradable plastic

EcoPure is a range of organic copolymer additives, which accelerates the biodegradation* of traditional, oil-based plastic products in a biologically active landfill. When EcoPure is added at approximately one per cent during the manufacturing of many traditional plastic products, the product can biodegrade faster than untreated plastics when disposed of in microbe-rich environments.

The addition of EcoPure does not negatively affect or require a change in the manufacturing process or the physical properties of the plastic application. For example, EcoPure treated PET water bottles will be just as durable, watertight, and have the same shelf life as an untreated PET bottle.

What makes EcoPure treated products revolutionary is their life after disposal, which becomes greatly reduced in a biologically active disposal environment. According to ASTM D5511-11/ISO 15985 test results, treated plastics take a fraction of the many years traditional plastics can take to biodegrade.

EcoPure additives are compatible with various types of plastics, including the following: PE, PET, PP, PS, Nylon, PVC, EVOH, ABS and Polycarbonate.

Biodegradation of plastics treated with Ecopure Microbial Quorum Sensing

Microbes use quorum sensing to coordinate certain behaviours based on the local density of the bacterial population. Microbes that use quorum sensing constantly produce and secrete certain signaling molecules (called autoinducers or pheromones). These microbes have a receptor that can specifically detect the signaling molecule (inducer). When the inducer binds the receptor, it activates transcription of certain genes, including those for inducer synthesis.

As the microbial population grows the concentration of the inducer passes a threshold, causing more inducer to be synthesised. This forms a positive feedback loop, and the receptor becomes fully activated. Activation of the receptor induces the up regulation of other specific genes, causing all of the cells to begin transcription at approximately the same time. This coordinated behaviour of microbial cells can be useful in a variety of situations such as multiplying. (Read more – http://en.wikipedia.org/ wiki/ Quorum_sensing) Biodegradation of Ecopure treated products is aerobic or anaerobic or a combination of both aerobic (with oxygen) and anaerobic (without oxygen). Microbes found in both conditions will be attracted to our biodegradable products and will colonise on the plastic, which will result in biodegradation. The stages of the complete process of anaerobic biodegradation (landfill conditions) with Ecopure products are listed below:

It consists of four stages:

  • Aerobic
  • Anaerobic, Non-methanogenic
  • Anaerobic, Methanogenic Unsteady Phase
  • Anaerobic, and Methanogenic Steady Phase

Figure 1 below shows the process:

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Time period for biodegradation

There are a number of factors which contribute to the length of time required to fully biodegrade.

  • Type of plastic (i.e. LDPE, PET, and PS)
  • Surface area of the product
  • Mass and thickness of the plastic
  • Microbial activity {which is further dependent on presence or absence of oxygen, temperature and pressure of the landfill/ surrounding environment etc}.

For example a bottle with smooth surfaces will biodegrade slower than if the bottle had grooves. Generally thin films, bags will biodegrade in India’s wet landfill conditions within a year. The PET bottles, rigid plastics (HDPE, PP, ABS), multilayered plastics packaging will take a maximum of three years. Since ASTM 5511-11 methodology does not allow extrapolation of biodegradation, exact time to biodegrade cannot be estimated. Nature and its elements have a big role to play, which cannot be predicted by human beings.

Standards and tests

Ecopure is tested on ASTM 5338 (aerobic biodegradation by CIPET, Chennai on ASTM D 6400 Standard) ISO 14985/ASTM 5511-11 by Intertek, Mumbai ( anaerobic biodegradation), FDA, US and Food Grade, CIPET, Chennai (polyethylene migration tests on acetic acid and water). There are other third party labs across the world, which have tested different types of polymers. (Log on to http://www.ecopure.in)

Shelf life

There are three types of microbial environments; suspended, dormant and active. Polymers treated with EcoPure require an active microbial environment in order to break down. In most environments such as warehouses, offices, store shelves the microbial environment is suspended or dormant and would not be considered an active microbial environment. So these treated product will have unlimited shelf life in warehouses and other dormant and/ or suspended environment.

Recyclability

Products treated with Ecopure are recyclable and reusable without any change in processes or machines. The recycled products (if not treated with Ecopure) would NOT degrade as optimum per cent of Ecopure in any product is required for biodegradation.

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Value vs cost of Ecopure Pharma packaging, NGT and scientific evidence

Ministry of Health notification on baning usage of PET in oral medicine has no long term research basis. European drug adminstration and US FDA5 have not foud any credible evidence of bisphenol or antimony poisoining in PET containers. FDA’s National Center for Toxicological Research (NCTR) have been studying BPA.

The NCTR researchers have been conducting in-depth studies of BPA since September 2008, when a report by the NIEHS and NTP called for more research into the potential toxic effects of BPA on fetuses, infants and children.

NCTR’s findings include:

  • The level of BPA from food that could be passed from pregnant mothers to the foetus is so low that it could not be measured. Researchers fed pregnant rodents 100 to 1,000 times more BPA than people are exposed to through food, and could not detect the active form of BPA in the foetus eight hours after the mother’s exposure.
  • Exposure to BPA in human infants is from 84 to 92 per cent less than previously estimated.

NCTR mathematical models showed that BPA is rapidly metabolised and eliminated through faeces and urine. They found that BPA is ‘exactly the opposite’ from some other toxins, like dioxin, that can stay in the body’s tissues for months or even years.

The centre’s toxicology research has not found evidence of BPA toxicity at low doses in rodent studies, including doses that are still above human exposure levels.

The 65th meeting of Drugs Technical Advisory Board the basis of Ministry of Health’s notification itself admits to a lack of long term scientific study. If a scientific decision is to be made how come DTAB quotes ‘absence of evidence’ does not entail ‘evidence of absence.’ Just by quoting jargons and not looking into studies by governments and their agencies like US FDA, a point is not proven.

BPA is mostly found in polycarbonate bottles.

Leachates and extractables can be even found in glass, which is touted as an alternative, inorganic oxides and heavy metals are well known leachates from glass. This is the medical reason for not using glass. Besides temperature effects on leaching have not been studied wide and deep enough in India to prove otherwise for PET pharma packaging.

US FDA makes it clear that boiling liquid may result in leaching in any material including PET, in this particular case maximum temperature of 40-45 degree centigrade cannot become a benchmark for determination of toxicity.

A reputed Elsevier study in International Journal of Hygiene and Environmental Health [Volume 212, Issue 2, March 2009] points out that the highest estrogenic activity detected in water extracts was equivalent to the activity induced by 23.1 ng/L of the natural hormone 17ß-estradiol, which is non toxic. A white paper in International Life Sciences Institute6 on PET (2000) on general toxicity and genotoxicity studies on PET, its monomers and its typical intermediates indicate that it does not pose a threat to human health.

Sustainability, plastic waste management and legal framework in India

In early 2011, the Ministry of Environment and Forests, Government of India came out with a framework of Plastics (waste) Management Notification after a panel of experts gave suggestions to it.

Firstly, does MoEF wish our young rag pickers to continue to pick up plastics in unhygenic and dangerous conditions?

Secondly, increasing thickness of bags will actually increase plastic waste in absolute volume in the landfill and in the environment ( through littering). Thickness (of plastic products) is a dangerous precedent to consider. It does not give a full picture of waste.

Thirdly, why only certain type of usage has been picked for plastic ban? Why not all sachets or food packaging?

Fourthly, why not plan an integrated waste collection system across India, which has been endorsed through its intermediate judgement by the honourable Supreme Court, in a public interest litigation filed by Karuna society. [Unfortunately, NGOs have been doing a better marketing job than the plastic industry, that too without any rationale or scientific evidence.]

Lastly, the standards for biodegradation seems to have been just copy-pasted in the 2011 notification, by MoEF without even going into details. Lab conditions for biodegradation have been set as standards. Biodegradable plastics have also been banned for food, without any scientific evidence.

States are going ahead and have started aping the MoEF on thickness of plastics, specially bags. Under the Constitution of India not only the manufacturers and the government but citizens of India are ‘bound’ by article 51 A (g), which says:

It shall be the duty of every citizens of India –g) to protect and improve the natural environment including forests, lakes, rivers and wild life, and to have compassion for living creatures;Yet Government of India and state governments are not even trying to create the legislative and implementaion framework, let alone implement the fundamental duties of citizens.

In the view of the above, Government of India and the Supreme Court should consider the contribution of plastics and its packaging in our modern life and its impact on increasing efficiency and productivity in the complete value chain of industries and society as whole.

A single point suffices the importance of plastics in our lives. More than 40 per cent of our food is wasted in India by GoI’s own admission and various reports of Indian institute of Packaging, CFTRI, Mysore, ENVIS, TIFAC (996) and MS Swaminathan (Planning Commission 1981).

Central Pollution Control Board has supported biodegradable plastic packaging in early 2000’s in its report, yet MoEF failed to take cognisance.

Conclusion

Biodegradable plastics are an important part of the value chain of waste management. Governments and the courts should be made more aware of these, their properties and advantages to society, so that they can take informed decisions.

NGOs and public should also fully arm themselves with complete knowledge of different aspects of packaging and the value chain with different materials and their carbon, water and energy footprints and impact on the environment and health of human beings and then act. The concept of 3Rs: Reduce, Reuse, Recycle would be highly beneficial for our country.

Likewise, packaging decisions should be based on real scientific studies and collaborating with institutes from other countries and independent sources, when labs like CIPET do not have the capability to do such studies. There is no proof of presence of toxic amounts of endocrine disruptors or carcinogen triggers in PET. The government and PET manufacturers should relook into this matter.

References:
1) India Carbon Outlook: http://india.carbon-outlook.com/content/which-more-sustainable-paper-or-plastic
2) DEFRA, UK January, 2010 http://randd.defra.gov.uk/Default.aspx?Menu=Menu&Module=More&Location=None&Completed=0&ProjectID=16263 & http://www.greenwashingspy.com/?p=844
3) http://www.nature.com/news/2011/110421/full/news.2011.255.html
4) http://www.ecopure.in
5) http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm297954.htm
6) http://www.ilsi.org/europe/publications/r2000pac_mat1.pdf

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