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SMC: How biodegradable are bags?
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.
Science Media Centre NZ
Our aim is to promote accurate, evidence-based reporting on science and technology by helping the media work more closely with the scientific community.
The Science Media Centre is New Zealand's only trusted, independent source of information for the media on all issues related to science. Thousands of news stories providing context from and quoting New Zealand researchers have been published as a direct result of our work.
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