Issue 02/2019

Opinion
No solution for pollution?
Will PLA solve the plastic pollution problem in island
countries like Singapore?
Global concern over single-use plastics escalated
recently after the European parliament
- in a bid to stop pollution of the
oceans - voted in October 2018 to ban the use of
these plastics in products such as straws and
cutlery [1].
In southeast Asia, Bee Yin Yeo, Malaysia’s
new science and environmental minister, was
selected as one of Nature’s top 10 “people who
mattered” in 2018 , in acknowledgment of her
strong stance against plastics pollution [2]. A
heated discussion about the very low plastics
recycling rate (6% according to the latest data
released [3]) was unleashed in newspapers
in Singapore; and a new non-profit and nongovernmental
organisation (Zero Waste SG) [4]
was established in 2018 dedicated to helping
Singapore eliminate waste, including plastics
waste, and to accelerate the shift towards zero
waste and the circular economy. Unsurprisingly,
the idea of biodegradable plastics, as an alternative to
single-use plastics, has become a highly popular one, not
only in scientific research, but also among policymakers.
PLA is widely regarded as the most promising, because of
its unique properties and relatively low price. PLA accounted
for 24% of the global production capacity for biodegradable
polymers, just after starch blends (44%). Yet while PLA
has indeed passed the standardized biodegradation tests
required by ASTM and OECD, the fact that its biodegradation
rates are highly dependent on humidity, temperature as well
as concentrations of microorganisms was largely ignored.
Recently, Frederik R. Wurm, head of the research
group “Functional Polymers” at Germany’s Max Planck
Institute for Polymer Research, examined the impact of
biodegradable polymers, including PLA, on the environment
and on society. In his critical review [5], he pointed out
that PLA is non-degradable in water or in seawater. I fully
agree with his view that it is our duty as scientists to take
part in the general discussion and to inform the public in
a responsible and honest way about the possibilities and
limitations of biodegradable plastics. To that end, I extracted
the information about PLA degradation from this review
and conducted a search on Google Scholar for the term of
“biodegradation of PLA” or “biodegradation in seawater”,
in order to ascertain whether PLA can solve the problem
of plastics pollution in island countries like Singapore (with
Singapore as an example for analysis).
End up environment of plastics waste in
Singapore
According to local media reports [6,7], only 6 % of the
locally produced plastic waste is currently recycled. The
remainder, for the most part, is incinerated. However,
By:
Liuqun Gu
Department of
Biomedical Engineering
Jinan University
Guangzhou, China
whatever is left is either exported or is leaked into
the environment, ending up in the ocean and causing
plastic waste pollution. Hence it is easy to conclude
that the problem of plastic pollution in Singapore is
the plastic polluting the ocean.
If the problem of ocean waste plastic is to
be solved, the plastics used in the future
must be biodegradable in seawater and
marine environment.
PLA was shown to degrade quickly under industrial
composting conditions and was degradable at a
slower rate in soil conditions or landfill. However, it
is not degradable at all in fresh water or seawater
(in test conditions varying from several month to one
year) according to three academic studies [8,9,10]
and a research report by the state of California [11].
Although the artificial seawater used in a few of the
tests might not be exactly the same as the seawater
near Singapore or other island countries, the inertness
of PLA is still a point that is well worth special consideration.
In summary, replacing single-use commodity plastics with PLA
is unlikely to solve the problem of waste plastic pollution in island
countries like Singapore, because PLA will not degrade in fresh
water or seawater. In addition, the label of “biodegradable” or
“disposable” might encourage irresponsible disposal by members
of the public, as most people believe that “bioplastics” are
biodegradable under any conditions.
linkedin.com/in/liuqun-gu-b1401472/
References
[1] Single-use plastics ban approved by European Parliament, BBC news on 24 Oct.
2018; www.bbc.com/news/world-europe-45965605
[2] Bee Yin Yeo: force for the environment; www.nature.com/immersive/d41586- 017-
07763-y/index.html
[3] www.nea.gov.sg/our-services/waste-management/waste-statistics-and-overallrecycling
[4] http://www.zerowastesg.com/
[5] T. P. Haider, C. Volker, J. Kramm, K. Landfester, and F. R. Wurm, Plastics of the
Future? The Impact of Biodegradable Polymers on the Environment and on
Society Angew., Chem. Int. Ed. 2019, 58, 50–62.
[6] Have our recycling efforts in Singapore gone to waste?
https://thepeakmagazine.com.sg/lifestyle/have-our-recycling-efforts-insingapore-gone-
to-waste/.
[7] Plastics still pose a problem for Singapore; www.businesstimes.com.sg/
consumer/plastics-still-pose-a-problem-for-singapore
[8] J. Greene, Biodegradation of Biodegradable and Compostable Plastics under
Industrial Compost, Marine and Anaerobic Digestion, SciEnvironm, 2018, 1, 13-
18.
[9] A. R. Bagheri, C. Laforsch, A. Greiner, and S. Agarwal, Fate of So-Called
Biodegradable Polymers in Seawater and Freshwater, Global Challenges, 2017, 1,
1700048.
[10] R. T. Martin, L. P. Camargo and S. A. Miller, Marine-degradable polylactic acid,
Green Chem. 2014, 16, 1768.
[11] Report Topic: PLA and PHA Biodegradation in the Marine Environment by
Department of Resources Recycling and Recovery, State of California, March 5,
2012.
bioplastics MAGAZINE [02/19] Vol. 14 43