Which plastics are really green? Confusion reigns
When Simon Upton came back to New Zealand last year after a long stint overseas, he was gobsmacked by the amount of plastic we use.
The new Parliamentary Commissioner for the Environment went to a supermarket and the first bag he picked up was labelled biodegradable.
‘‘I thought: What does that mean?’’ Upton said.
So the man with powers to investigate environmental concerns thought that if he didn’t know, other people probably didn’t either.
Upton had been working for the OECD in Paris as environment director since 2010.
Given the confusion around biodegradable and compostable plastics and growing concerns about the scale and lifetime of plastics, Upton has gone out to clear the air.
In a letter to Associate Minister for the Environment Eugenie Sage and Minister for the Environment David Parker, Upton said the combination of widespread single-use plastic in the retail sector and growing public concern were ‘‘a fertile climate for the promotion of plastics that are said to be biodegradable, degradable or compostable’’.
He said the terms ‘‘can become a serious source of confusion and even lead to worse environmental outcomes’’. ‘‘The results of my inquiry suggest that both businesses and consumers face a bewildering array of claims about plastic that can lead to misunderstandings on the part of even the most environmentally conscious citizens.’’
Upton also highlighted four areas regarding biodegradable plastics that needed ‘‘urgent attention’’: Sorting out the terminology, standards and labelling, end of life infrastructure – including recycling, composting, and landfill facilities, and clarity of environmental goals.
In order to avoid confusion on the issue, in his latest report he has laid out the details of biodegradability and compostability and how they work. While the original document is long, it is a one-stop shop for what you need to know. This is an extract:
What does it mean to say that a plastic is biodegradable?
Biodegradable means that an item can be broken down by the action of living organisms, typically microbes. In the case of biodegradable plastics, this process is enabled by enzymes that are produced by microbes that use the plastic as a source of energy – the microbes are essentially eating the plastic for food.
New Zealand does not have a standard for biodegradable or compostable plastics. However, some plastic manufacturers have voluntarily sought certification using some existing international standards so they can label their products accordingly. An industry working group has been set up to consider whether adoption of a standard in New Zealand would be useful.
What do biodegradable plastics break down into?
Ultimately, a biodegradable plastic will break down into small molecules, such as carbon dioxide, methane and water, as well as waste from microbial activity.
Plastics, including biodegradable ones, often have other components mixed in as ‘‘additives’’ for various reasons. These additives may be released when the plastics degrade.
What does it mean to say that a plastic is compostable?
Composting involves the breakdown of biological material such as green waste from garden clippings or food scraps into humus. Industrial compost facilities are designed to accelerate microbial growth by controlling moisture, airflow, microbial activity and the proportions of different organic wastes. As the microbes consume the waste, they generate heat, which accelerates the breakdown. The resulting product, compost, is then used to return organic matter to the soil. Home composting involves a similar process but on a much smaller scale, so it may not generate as much heat and will likely result in a slower breakdown process