(Photo: Sugarcane crop. Credit: Chetan Bisariya, Flickr Creative Commons)On the heels of Lego’s plans to use plant-based plastic for a new line of pieces, British researchers caution that bioplastics can pose hidden risks for companies.
Sharon George and Deirdre McKay from Keele University in the UK argue in an op-ed for The Conversation that “plant-based” doesn’t necessarily mean sustainable. George, an environmental science lecturer, and McKay, social geography and environmental politics senior lecturer, highlight several key challenges for corporations.
One is that bioplastics can be fossil fuel-based. The Plastics Industry Association definition states that bioplastics are either made from a renewable resource or break down completely, or are both bio-based and biodegradable. An infographic from the association shows that bioplastic sources are wide-ranging and include methane, petroleum, corn, and cellulose.
By definition, materials classified as bioplastic aren’t necessarily biodegradable. “Even if a plastic is classified as ‘biodegradable,’ that just means it can be broken down by bacteria or fungi, but this can still take decades and leave toxic residue behind,” George and McKay wrote. They add that bioplastics classified as compostable could still require high-temperature industrial processing to break down.
Lego’s new flexible bioplastic pieces will be made with ethanol extracted from sugarcane. Bioplastic sources that require farming — sugarcane, castor beans, canola, soybeans, corn — can come with environmental risks, the British researchers say.
“Farming sugarcane can put huge stress on the environment, relying on large plantations that use pesticides, herbicides, and fertilizers as well as significant amounts of water,” they wrote. Large resource-intensive plantations could also displace local farmers, the researchers say, edging them into marginal and vulnerable land.
For companies that want to use ethanol, George and McKay suggest producing it by farming blue-green algae, household waste, or the residues of coffee production instead. “There are far more sustainable sources of ethanol than sugarcane,” they wrote.
Currently, only between 1% and 2% of Lego products are made from polyethylene, which limits the amount of product that can ultimately be replaced with sugarcane plastic. Most Lego pieces continue to be made from oil-based plastic. The toy company says its bricks are designed to be reused and handed down through generations. For consumers, they emphasize donation and recycling unwanted pieces. Last month Lego joined the How2Recycle.
Despite their critique, George and McKay call plant-based plastic products like the ones Lego plans to produce a small step in the right direction.
“Truly green plastic needs more than sustainable raw materials and manufacturing techniques,” they wrote. “Sustainability must include the product’s whole life-cycle and the social conditions in which those raw materials are produced.”
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