Page 16 - Plastics News May 2020

Single-use plastic bags and their alternatives Recommendations from Life Cycle Assessments
Summary from all studies (by different environmental impact categories
Biodegradable bags decompose and contribute less to makes the age of these data less critical. However, new
the impacts of littering, compared to conventional and innovative plastics, including bio-based
SUPBs; however, the LCA results indicate they might be alternatives, are still at the beginning of their
the worst option when it comes to climate impacts, improvement curve, therefore recent data are
acidification, eutrophication, and toxic emissions. important as the technology and scale of production
A plastic bag with a prodegradant additive (oxo- might change significantly over time.
degradable bag) has almost identical impacts compared
to the conventional SUPB. It has less visual impact as Recommendations for policy makers and other
litter, because it degrades into small fragments. strategic decision-makers:
However, the problem of microplastics might still Selecting bag types:
remain, and the prodegradant can cause problems in
recycling processes.

When using these findings for decisions, it should be
noted that the production processes of innovative
materials such as bio-based or degradable plastic bags
are relatively new and might improve significantly over
time. Most of the seven LCAs are 5-10 years old and some
of the input data used in the studies are significantly
older.

It can be concluded that reducing environmental
impacts of bags is not just about choosing, banning,
recommending or prescribing specific materials or bags,
but also about changing consumer behaviour to increase
the reuse rate and to avoid littering. The shopping bag
that has the least impact on the environment is the bag
the consumer already has at home. Bags that are designed for multiple uses (reuse) have
lower impacts than SUPBs in most environmental impact
categories, if they are actually used a sufficient number
In addition to the above summarised findings, the review of times (50-150 times for cotton bags, 4-8 times for
provided some general findings, which are presented paper bags, 5-10 times for reusable LDPE bags for, and
below.
10-20 times for durable, non-woven PP bags). These
numbers might not be reached, depending on consumer
Critical parameters influencing the results:
behaviour etc.
The number of uses greatly influences LCA results: Banning single-use plastic bags while favouring other
increased number of uses (for shopping and eventually as
single-use alternatives results in environmental trade-
bin liner) will reduce the impacts of all products.
offs. For example, single-use paper bags have less
impact of littering, compared to SUPBs, but often have
The final waste-management option is decisive:
incineration or efficient sorting including recovery can higher impact on most other environmental categories
(Climate Change, Acidification, Eutrophication, Ozone
positively influence the environmental impacts of cotton
Depletion, Land use change). When defining policies on
and paper bags. The LCAs indicate that landfilling is the bags, these trade-offs should be evaluated in the specific
least preferred option for cotton, paper and geographical context.
biodegradable bags as degradation releases methane,
which has a strong impact on the climate.
In countries with under-developed waste-management
systems and poor infrastructure for collection and
The age of the data and of the technology being assessed recycling, the arguments against SUPBs are stronger
needs to be considered. The production of conventional because littering and its associated environmental
plastics is a mature and large-scale technology, which

MAY 2020 16 Plastics News