Community Scoop

SMC: How biodegradable are bags?

Press Release – Science Media Centre

How biodegradable are bags? Plastic bags are currently public enemy number one, but are biodegradable bags any better?How biodegradable are bags?
Plastic bags are currently public enemy number one, but are biodegradable bags any better?

Writing in the latest issue of Royal Society Open Science, European researchers have argued that the existing industry standards and testing methods are insufficient to predict the biodegradability of single-use plastic carrier bags within lakes, rivers and oceans.

AUT Professor of Engineering Thomas Neitzert said the research helped “destroy the thinking that a plastic bag with a label ‘biodegradable’ is safe for the environment”.

“The co-existence of conventional plastic bags and so-called biodegradable plastic bags of compostable materials is also upsetting current recycling operations and is confusing the general public.

“Biodegradable plastic bags are in many cases made from crude oil, requiring carbon-based production processes and are emitting CO2 or methane when degrading. On the way to a low carbon economy, we should, therefore, carry a reusable bag made from cloth or jute, like our parents did.”

University of Auckland senior lecturer Dr Ivanhoe Leung, co-deputy director of the Centre for Green Chemical Science, said plastic pollution was “one of the most challenging environmental issues that is facing the world today”.

The science behind biodegradable or compostable bags had gone a long way since they were first developed, he said, and given the right conditions they can break down into harmless materials within a few months.

“The challenge, however, is to separate these biodegradable plastic materials from the waste stream so that they can be broken down under the right conditions.

“For example, undesirable substances like acids or methane gas can be produced from biodegradable plastics if they are broken down in places that lack oxygen. These could be landfill sites, or anaerobic marine habitats like saltmarshes or brackish waters.”

University of Waikato’s Professor Kim Pickering said it was important to assess how long things take to degrade in real life situations, and what they break into.

“If it is to be assumed that we cannot prevent some plastic products getting into the environment, then biodegradable plastics could be a step in the right direction (depending on the product), but it shows that there are great uncertainties regarding the impact these could have on the environment and so we should still assume responsibility of waste plastic and consider its disposal, whether biodegradable or not.”

The SMC gathered expert comments on the paper.

Quoted: NZ Herald
“If western science is to become relevant to indigenous cultures, one way forward is through the language of that culture.”

AUT ecologist and mātauranga Māori expert Dr John Perrott
after an international journal featured a research paper summarised in te reo Māori, as well as English.

SMC’s new media advisor
The Science Media Centre welcomes a new staff member this week — Rachel Thomas.
Rachel joins us from Stuff and the Dominion Post where was senior health reporter and an acting news director.
Prior to this, she reported for the Waikato Times, the Piako Post and the Franklin County News, scooping several awards over the years, including a Nib health scholarship to investigate the impact of sugar taxes in the US.
Rachel studied journalism at Wintec, graduating in 2011. She brings a wealth of relevant experience covering health, science and environment news, and we are very pleased to welcome her to the SMC.
Rachel joins fellow media advisor Dr Sarah-Jane O’Connor as a main point of contact for media queries and expert reaction comments and Q+As.

Policy news & developments

New guidelines on climate change: New recommendations from the Ministry for the Environment discuss the need for urgent, proactive planning in every organisation in response to climate change.

Nurses’ guidance panel results: The Government-commissioned panel has made a list of recommendations to address the nurses’ pay and working conditions claim, including a 3 per cent increase on all MECA wage rates from June 1.

Tax fairness bill reaches next step: The Taxation (Neutralising Base Erosion and Profit Shifting) Bill, aimed at preventing large multinationals from exploiting rules has passed through its second reading.

Cremation certificates: Nurse practitioners have been given the authority to issue cremation certificates.

Flu tracking: The Ministry of Health has adopted an Australian online tool which lets people log flu-like symptoms.

Algorithm stocktake: A project will assess how government agencies use algorithms to analyse people’s data, in an effort to ensure transparency.

Boosting gaming: NZTech will take a snapshot of New Zealand’s interactive media sector and look at how to grow our creative tech sector and digital economy.

New Director-General of Health: Dr Ashley Bloomfield replaces Chai Chuah as the new Director-General. Dr Bloomfield steps up from an interim chief executive role at Capital & Coast DHB.

Total Diet Study published: MPI has published its latest survey on common foods which measures exposure to certain chemicals, such as agricultural compounds, contaminants, and nutrients.
Adapting to climate change
The Climate Change Adaptation Technical Working Group has reported back to Government with recommendations on what New Zealand needs to do to adapt to the effects of climate change.
The report’s 21 recommendations include developing a national adaptation action plan and a national climate change risk assessment, alongside reviewing existing legislation to better align with adaptation considerations. The group also called for funding mechanisms for climate change adaptation and work into reflecting the future costs of climate change adaptation within investment and planning decisions.
Co-chair of the working group Dr Judy Lawrence said the report came at a time “when New Zealand is waking up to the reality that climate change affects what we do, how we do it, and where we live” and that the recommendations challenged the status quo of reacting to climate events as they occurred.
Climate Change Minister James Shaw said New Zealand tended to have “point-in-time assessment of risks, rather than one where you are constantly assessing risks and adapting as you go”.
Local Government New Zealand President Dave Cull said councils were caught in a lose-lose scenario where they were left liable if they didn’t make new buyers and residents aware of the dangers, but vulnerable if those warnings affected property prices.

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