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Context - The global production of plastics is increasing, and that increase is accompanied by an increase in plastic waste.
Part of this waste makes its way into the marine environment in the form of micro-plastics, small particles of plastic that can either be produced as plastic pellets, or result from the degradation of plastic objects such as bags, clothes, household items as well as building materials and fishing and aquaculture gear that has been discarded or lost.
What do we know about the extent of this problem?
You can also read a recent highlight on the topic: Sources, fate & effects of micro-plastics in the marine environment.
1. Introduction: plastic waste and micro-plastics in the oceans.
The amount of plastic waste is increasing
Global production of plastics is increasing every year (245 million
metric tonnes in 2008) and the amount of plastic litter that is finding
its way into the environment and into the oceans is also increasing,
especially in the areas of the world where waste management practices
are not keeping up with this rapid increase.
Although it is known that the amount of plastic waste is increasing,
there is a general lack of information on how much of this plastic
debris finds its way to the oceans and on how much of it there already
is in the oceans. Once micro-plastics are in the oceans, this transport
and deterioration process is not possible to influence. The only point
of control is on the amount of waste that enters the oceans.
The widespread occurrence of large plastic fragments in the sea and
the direct impact this can have both on marine fauna and on legitimate
uses of the environment has been well documented. In recent years the
existence of smaller plastic particles referred to as micro-plastics and
their potential impact has received increasing attention. This concerns
particles smaller than 5 mm, and there is increasing evidence that such
particles can be ingested by marine
organisms, and could harm them, although the effect of micro-plastic
fragments on the health of animals
is still largely unknown.
2. What kind of plastic waste ends up in the marine environment?
Truly biodegradable plastics tend to be expensive and are not suitable for all applications.
The term plastic encompasses a wide range of
polymers, including rubbers,
elastomers, textiles, and thermoplastics. The global production of
plastics has increased from 1.5 million metric tonnes in 1950 to reach
245 million metric tonnes in 2008. Plastics are produced all around the
globe, and the continuing growth of the demand will be met with
In Europe in 2009, of the 45 million metric tonnes of plastics
consumed, 11 million ended up in landfills or in the environment. It is
acknowledged by industry and Government alike that recovery and
recycling of plastics need to increase dramatically.
There are some newer plastic types on the market, for instance used in
carrier bags or packaging, that are often assumed to be biodegradable.
These include so called “Bio-plastics” that do come from renewable
resources but are not necessarily biodegradable. To be called
“biodegradable” a material needs to be broken down by living organisms
in specific conditions into its constituent parts: carbon dioxide,
water, inorganic compounds and biomass. These conditions may occur in
industrial composters but not in the ocean, and thus many
“biodegradable” plastics will not break down in the oceans any faster
then other plastics. Truly biodegradable plastics, such as polylactic
acid (PLA), tend to be more expensive and are not suitable for many
applications requiring durability.
The majority of plastic waste entering the seas and oceans originates
from land-based sources, but there are also sources in the oceans such
as ships, oil platforms, and fishing or
3. What are micro-plastics and how do they enter the marine environment?
Pellets used in plastics manufacturing
Micro-plastic particles, defined here as particles of less than 5mm in
size, can arise through four separate processes:
- deterioration of larger plastic fragments;
- direct release of micro particles into waterways and via
- accidental loss of industrial raw materials during transport
or trans-shipment, at sea or into surface waterways;
- discharge of sewage.
It is likely that the amount of plastic waste in the ocean will
continue to increase, driven primarily by the inexorable rise in
plastics consumption and the continued inadequacy of re-use, recycling
and waste management practices in many parts of the world.
Lethal interactions of large plastic items with animals such as
seabirds, marine mammals and turtles through entanglement or
ingestion are relatively well
known, but the non-lethal impacts on individuals and populations are
unclear. Even less is known about the potential impacts of
micro-plastics on a wide range of smaller organisms, exposed to various
particle sizes and chemical constituents.
4. Can micro-plastics transport contaminants into the marine environment?
Persistent, bioaccumulating and
toxic compounds can be present in the
atmosphere or in water.
Plastics found in the ocean contain some of these contaminants, either
as additives added to the plastics during their production or as
compounds that attach to plastics once they are in the environment.
The fate of those contaminants attached to plastics is unclear. The
way contaminants are attached to micro-plastics, by
absorption into the
polymer, is reversible, and
plastics can act as transporters from one area to another,
semi-permanent ‘sinks’ or potential additional sources if
ingested. Another possibility
is that for some contaminants the transport through plastics would be
minor compared to the transport of these contaminants through the
5. What is the impact of micro plastics on the marine environment?
While the effect of large debris is well documented, the effect of small particles is less well known.
Ingestion of plastics by animals
can already be considered an undesirable exposure, no matter what other
implications it might have. This ingestion could have detrimental
effects on the health of animals
either directly through the presence of plastics in their digestive
system, or through the release of chemicals.
While these chemicals and their potential effects on organisms in the
environment are well known, the way they interact with plastics once
they are in the gut of animals is less known. The fact that such
chemicals have been identified in plastics in the open ocean could on
its own indicate that there is the potential for harm. However, this
should be balanced by the knowledge that even in the absence of
plastics, these contaminants are present in the environment and
accumulate within the food chain.
The real unknown is to what extent plastics increase exposure of
organisms to contaminants.
One interesting approach to dealing with management of the coastal
zone is to integrate the concepts of
ecosystem services and their
valuation which might make tackling the problem more attractive when
considering the cost for action. It is however very difficult to apply
cost-benefit analysis to ecosystems.
6. What is currently being done in the world about the marine litter?
Here are examples of different initiatives that have been undertaken
in the world by different
stakeholders. Click on ‘more’ to
have more information.
Land-based sources: achievements within the UN system at a
Ship- and platform-based plastic litter – MARPOL 73/78 Annex V
UN global assessment processes
Examples of Regional Assessments
European Commission initiatives
USA, National initiatives
Coastal municipalities and local authorities
Chemical industry policies regarding marine litter
7. Is a global assessment of micro-plastics in the marine environment necessary?
A global assessment of micro-plastics could be beneficial at this time
and there is both sufficient public concern and a need to provide
further objective information on the topic to enable policy makers to
act. This assessment would need to take into account not just micro
plastics but also marine debris in general, in order to understand the
general context and processes involved.
- There is a need to identify and develop global environmental
standards, as well as broadly applicable indicators, with which to
benchmark these standards.
- There is a need for better understanding of the dynamics of
persistant, bioaccumulative and toxic compounds (PBTs) in relation
- Methods need to be developed to measure and to limit the
quantities of plastics entering the oceans.
The main conclusion is that there is still very limited information on
micro-plastics in the oceans. We do not know how much of it makes its
way to the ocean and how it behaves once it is in the ocean, both in
terms of movement in the ocean and in terms of degradation,
fragmentation, and modification of properties due to weathering. In
addition, very little is known on the possibility for micro plastics to
carry contaminants and on the effect on the environment of plastic