b'SENSE, NONSENSE AND SCIENCEBY: JOE SCHWARCZBIOPLASTICS AND THE PLASTICWASTE PROBLEMI n the classic film The Graduate, a family friend corrals young Benjamin, who had just graduated from college, and whispers into his ear: Plastics. The year was 1967 and plastics were the mira-cle materials that changed lives. Virtually every industry from airplane and car manufacturers to hospital equipment and cookware suppliers benefitted from plas-tics. Women flocked to Tupperware parties and vinyl records were the rage. My, how times have changed! Plastics have become a pariah, pollutants that are sullying and endangering the environment. If Benjamin were embarking on a career today, the whis- sarily biodegradable. That term refers toother hand, the land dedicated to the crops pered word would likely be bioplastics,substances that can be broken down byrequires deforestation and the use of ferti-with further qualifiers such as degradable,microbes normally found in the environ- lizer and pesticides.biodegradable, oxo-degradable recycla- ment. Food scraps, human and animalWhile polyethylene is not biodegrada-ble or compostable. waste, paper, wool and fallen leaves areble, it is recyclable. But you have to remem-These terms have infiltrated advertis- biodegradable but the speed at which thisber that recyclable does not necessarily ing as the plastics industry attempts to copehappens depends on the conditions. A cupmean recycled. Unfortunately, much of the with the negative image of beaches defiledmade of PLA will biodegrade quite quicklyplastic that goes into the recycling bin ends with plastic bottles, garbage patches in theif buried in soil but will not break downup in landfills or incinerators. Separation of ocean, shopping bags in gutters and strawsin a landfill. It is, however compostable,plastics is the big problem for the recycling up turtles noses. Indeed, items made fromwhich is why it is used to make compostindustry. Biodegradable and compostable the most common plastics, such as polyeth- bags. Note, though, that compostableplastics are difficult to separate from other ylene (PE), polypropylene (PP), polyethyl- does not mean that the plastic will breakplastics and can contaminate the recycling ene terephthalate (PETE) and polyvinyldown in the compost heap in your backstream and should not be put in the recy-chloride (PVC) are extremely durable andyard. Compostable on a label means thatcling bin.can stay around in the environment for dec- in a proper composting facility where tem- The term degradable on a label is ades and decades. perature and pressure are strictly controlled,misleading. It just means that in some Most plastics are made from naturalit will decompose into carbon dioxide, waterunspecified time, when exposed to the gas or petroleum, which is another concernand a complex mixture of organic com- elements, it will break down into smaller since these are non-renewable resources.pounds such as cellulose, hemicellulose andpieces. A plastic bag can be said to be So, we have a dual challenge. Find ways tolignin, referred to as biomass. This will notdegradable because if it happens to end cut down on the amount of plastic that getshappen in a landfill. up in the ocean it will eventually break discarded and find renewable resources thatFurthermore, some bioplastics may notdown into smaller pieces, but those smaller can be converted into bioplastics. be biodegradable or compostable at all. Forpieces of plastic can be a problem. Oxo-Bioplastics are produced partly orexample, polyethylene can be made fromdegradable means that metallic catalysts wholly from living species such as plants orethylene that is made from ethanol that inhave been added to the plastic to cause a microbes rather than from fossil fuels. Anturn is produced by fermentation of cornmore rapid degradation when exposed to example would be polylactic acid (PLA),or sugar cane. This polyethylene is identi- heat or light, but the breakdown products made from lactic acid, which in turn is pro- cal to the polyethylene made from ethylenemay not be biodegradable, so this is not of duced by the action of lactic acid bacteriaderived from natural gas or petroleum andgreat advantage.on starch from corn, cassava, sugarcane oris not biodegradable or compostable butThere is no simple solution to the plas-sugar beets. PLA is deemed to be a greencould still be advertised as a bioplastic ortic waste problem. But we can cut down plastic because it is made from a renewableas renewable polyethylene. Does it haveon use, although that is not easy. I have resource. It can be used to make transpar- any advantage over regular polyethylene?been reusing a shopping bag for a year and ent drinking cups, disposable tableware andMaybe. When the corn or sugar cane isremember that it is possible to drink a soft teabags. growing, it uses up carbon dioxide fromdrink without a straw. So, forget the straw. However, bioplastics are not neces- the air through photosynthesis. On theBetter yet, forget the soft drink.54ISEED WORLD EUROPEISEEDWORLD.COM/EUROPE'