Biodegradable plastic In 2009, the United States generated 30 million tons of plastic waste. Thirteen million tons was plastic containers and packaging, 11 million tons was durable plastic goods, and 7 million tons was non-durable goods, such as plates and cups. Only seven percent of this plastic waste was recovered for recycling. These statistics tell us two things; there’s a lot of plastic in the world, and it’s hard to get rid of. It’s a product that is built to last. Can biodegradable plastic help in the battle against plastic waste? Biodegradable means that a substance can be broken down by living organisms. ‘Biodegradable’ is a catch-all word, and covers a variety of types of plastic. In fact biodegradable plastics are not necessarily made from bio-material (e.g. plants) – some biodegradable plastics are made from oil in the same way as conventional plastics. Bioplastics are made from natural materials such as cornstarch. You may not be able to see the difference between a bioplastic and a plastic made from petrochemicals.
Over time (sometimes in only a few weeks) bioplastics break back down into natural materials. The cornstarch absorbs water and swells, causing the molecules to break. Bacteria in the soil then digest these molecules. Biodegradable plastics are either hydrodegradable or oxodegradable. They contain additives that cause them to decay in the presence of light and oxygen. But unlike bioplastics, biodegradable plastics are made of petrochemicals and don’t always break down into harmless substances.
A recent study found there was uncertainty about their impact on the natural environment. Researchers at Loughborough University in the UK found that bags made from oxodegradable plastic would still be lying around for several years before they broke down in the environment. They found the plastic is not suitable for recycling with other plastics, reuse or composting. Researchers said it could take somewhere between two and five years to break down, and it does not degrade in the absence of oxygen so is unlikely to break down in landfill, where much of it would end up.
Aside from the speed at which they decompose there are other issues of concern. Bioplastics are made from corn and maize, so food is being turned into plastic. By 2014, almost a quarter of US grain production is expected to be turned over to biofuel and bioplastic production, potentially causing a significant rise in food prices. The issue of promoting biodegradable plastic as a solution to littering also worries some campaigners, who rightly say that littering is an antisocial, irresponsible behaviour which should be tackled by changing people’s attitudes rather than the products they are throwing away.