2Microplastic Pollution
Sources of microplastic pollution
7.Most of the world’s ocean plastics by weight are large pieces of debris (e.g. fishing equipment, bottles and plastic bags). However, the dominant type of debris by quantity is microplastics.9 Microplastics have been reported at the sea surface and on shorelines worldwide. They are also present in remote locations including deep sea sediments and in arctic sea ice.10 The 5 Gyres Institute estimated that a total of 15-51 trillion microplastic particles have accumulated in the ocean, weighing between 93 and 236 thousand metric tonnes.11 The large variations in the estimates are because of scarcity of data, differences in models, and fundamental knowledge gaps.12
8.One source of microplastics arises from the breakdown of larger plastics. This happens due to the action of catalysing factors such as ultraviolet light, which can alter bonds in the plastic polymers.13 Dr van Sebille, Imperial College London, argued that “degradation is always happening and big plastics become smaller and, […], small plastics have bigger impacts.” He added that microplastic are “more damaging in general than larger plastics that break up as they move through the ocean.”14 Similarly, Professor Galloway, University of Exeter, said:
I think the issue is that as you break things down into smaller and smaller particles you increase the surface area. The surface area is where plastics can interact with chemicals and other things in the ocean and it is also the surface area from which things can leach out into the environment. […] One other thing to say is that microplastics overlap with the size range of food items for a lot of the creatures and animals that are at the base of the marine food web and that is the issue. It means that the plastics can be ingested.15
9.One of plastics’ greatest properties, its durability, is also one of the main reasons that it presents a threat to the marine environment when it becomes waste.16 The release of plastic into the marine environment has resulted in the rapid accumulation of persistent marine plastic debris in the world’s oceans.17 A 2014 report by the Norwegian Environment Agency estimated that the largest source of microplastic pollution was abrasion from tyres and road markings.18 Another major source was synthetic fibres from clothing, which are released into the wastewater environment from the effluent of washing machines in numbers as great as 1900 fibres per garment.19 Professor Kelly, King’s College London, said a lot of fibres “will contain various additional chemicals to give them additional properties and it will depend on what they have been mixed up with and what the components are on the fibres, so that will influence their degradability […].”20 Dr van Sebille, also suggested that fibres were going to be a very difficult problem to address as “garments have a use and are there because they work very well.”21 He further stated:
I feel that solving the fibre problem might mean engineering solutions, where it is about better filtering of wastewater treatment plants. […] civil engineering can do something at some point about taking these fibres out in a better way.22
In Europe, the Environment Investigation Agency estimates that there are between 68,500 and 275,000 tonnes of larger plastics (with the potential to fragment into microplastics) annually entering the marine environment.23 According to the Grantham Institute, Imperial College London, the total amount of plastic floating on the ocean surface is between 7,000 and 236,000 metric tonnes, whilst the amount of plastic entering the ocean in the year 2010 alone was 4.8 to 12.7 million tonnes.24 Dr Erik van Sebille, highlighted this discrepancy:
The large gap between the amount of plastic entering the ocean and the amount floating is because more than 99% of all ocean plastic is in reservoirs other than on the surface–the water column and ocean floor, [and] beaches.25
10.The majority of witnesses agreed that a significant proportion of marine litter was originally lost or disposed of on land before being blown or washed into the marine environment. DEFRA estimated this could be around 80%.26 There is also uncertainty over the identity of the major sources of microplastic pollution. A report by the Marine Conservation Society on beach litter showed that the source of 44% of litter items could not be categorised.27 In addition, UN GESAMP found that research on the potential ecological risks of microplastics was relatively new and that there was “a large degree of uncertainty surrounding this issue.”28
11.Different sizes of larger plastic objects can also lead to different impacts on the marine environments.29 There is limited information on the extent to which impacts vary according to the source or type of microplastic. Professor Richard Thompson, Plymouth University, states:
Discharges from point sources such as sewage plants, plastic processing factories and rivers can be identified. However, once in the environment it would appear that microplastics can move substantial distances, and accumulate in remote locations.30
DEFRA argues that “disentangling the effects of microplastics from the effects of these other factors is unlikely to be possible in the marine environment.”31 They state:
For larger items, it is frequently possible to identify what type of plastic (eg polyethylene, polypropylene) a particular piece of ocean debris is made of. However, when pieces become small and fragmented they are almost impossible to trace to their original source.32
12.Witnesses agreed that microplastic pollution in the marine environment originated from both land and marine-based sources. Although academic witnesses highlighted that microplastics are a transnational issue, Professor Richard Thompson, Plymouth University, states that “there is also evidence that substantial quantities of litter can remain on coastlines close to points of entry to the sea.”33
13.There is significant public concern around microbeads, however, they make up a small proportion of total microplastic pollution. The wider issue of microplastic pollution cannot be set aside once microbeads have been dealt with. We recognise the research is still relatively new and subject to uncertainties. We recommend that the Government work towards a systematic strategy for researching and mitigating sources of microplastic pollution. We suggest that synthetic fibres and tyres are two sources that should be examined at an early stage.
Microplastic environmental and health impact
Marine environment pollution
14.The small size of microplastics means that they can be ingested by marine life. It is difficult to make predictions about the risks of ingesting microplastics due to the variety of composition, shape and size.34 Toxicity could be caused by the plastic polymer itself, the additives it contains, or by other chemicals that associate with microplastics when they are in the ocean.35 UN GESAMP list the potential effects of microplastics on marine organisms as follows: physical effects such as obstruction; chemical effects due to transportation of toxic chemicals; impaired health; impacts on population and ecosystems; and dispersal of damaging pathogens.36
15.There have been experiments into the effect of plastic ingestion for marine species, although some of these experiments expose animals to a higher concentration of microplastics than has been reported in marine ecosystems.37 The magnitude of effects and life stages at which they are affected varies between species.38 There are also many other marine environmental pressures which make it difficult to isolate the sole effect of microplastics upon marine species.39
16.Microplastics are ingested by a wide range of wild life, and also commercially farmed species. According to Fidra, an environmental charity, some microplastics pellets in the range of 2-3mm can be mistaken for fish eggs by marine wildlife and seabirds, such as puffins.40 Plastic particles can be trapped in the stomach for several months and lead to weight loss and malnutrition.41 Over 280 marine species have been found to ingest microplastics, including many with important roles in food chains and the functioning of marine ecosystems.42 Microplastics can be ingested by mussels, crabs, zooplankton, and sea squirts.43 There is evidence that ingestion of microplastics can lead to reduced feeding rates, less energy for growth and lower reproduction. The magnitude of effects varies between species, and some animals appear only to be affected at certain stages of their lifecycle.44 In an experiment conducted by Dr Dannielle Senga Green, University of Warwick, repeated exposure to a sedimentary habitat associated with flat oysters found that there was a reduction in important grazing organisms, such as juvenile periwinkles and isopods.45 A reduction in these organisms could have knock-on effects on marine ecosystems.
17.Professor Richard Thompson, Plymouth University, in a study of 504 fish from the English Channel, found that over one-third of the fish examined had plastic in their digestive tract.46 He also found that some species of seabirds had ingested larger quantities. Dr van Sebille, Imperial College London, also conducted a study on the effect of plastics on birds and seabirds. He said:
We found that 80% of seabird species ingest plastic into their stomach, and that if you weigh that plastic, the amount of plastic that a typical seabird now carries around can be up to 10% of their body weight.47
18.There are other environmental concerns which are not related to ingestion of microplastics. For example, microplastics can provide a surface for marine insects to lay their eggs.48 This could lead to an increase in certain species and a potential disruption in ecosystems.49 According to Brunel University, microplastics can also host microbial communities and can transport pathogens such as the Vibrio strain of bacteria, which could have an impact on wildlife health.50 The community of microbes associated with plastic fragments is different to that normally found in seawater, which could have ecological consequences.51 Professor Tamara Galloway argues:
We know very little about the transfer of plastics from surface waters to the rest of the marine environment. […] Little is known of the transfer of microplastics across the gut into tissues and the transfer of associated chemicals. We need to understand the pathways, mechanisms and effects.52
19.Although some studies have shown that plastics can transfer chemicals to organisms upon ingestion, is not known to what extent this could result in harmful effects.53 DEFRA state:
The evidence base on the effects of micro-plastics in the marine environment is limited. However, they do not biodegrade, they accumulate in the marine environment, they can absorb toxic chemicals and pathogens, and their small size means they have the potential to be ingested by marine organisms.54
20.The impacts on the marine environment are still being researched. However, there is evidence that there is scope for significant harm to the marine environment. Microplastic pollution is potentially more environmentally damaging than larger pieces of plastic because small pieces of plastic are more likely to be eaten by wildlife and have a greater surface area which can transfer chemicals to and from the marine environment.
Impact on human health
21.It is uncertain whether microplastics that are ingested by humans can be transported into tissues. Microplastics are widely used as carriers for medicines, and can transfer into tissues in humans. Thomas Maes, CEFAS told us:
There is lots of research available from the other side - the medicine side. They use microplastics as carriers for medicines… as vectors for delivering medicines to those areas where they want them to be active.55
He went on to say:
[The evidence] shows it could transfer to several layers of the human body, in simple layman’s terms. [..] If [microplastics used in medicine] can transfer to certain tissues to deliver the medicine, then it could also transfer to the tissues without the medicine, I would assume.56
22.Microplastics are present in seafood sold for human consumption, such as mussels from the North Sea.57 It is possible that the gut wall could stop microplastics from entering tissues, but very small particles could potentially pass through.58 Evidence submitted by DEFRA said that the smallest particles, known as nanoplastics, can even permeate cell membranes, as well as gut tissues.59 Once inside tissues, it is theoretically possible for microplastics to interact with biological tissues in a toxic manner, but this has not been tested.60
23.An essential factor determining whether microplastics present a physical threat and/or act as a vector for transferring chemicals is the ability for these particles to be absorbed. Smaller particles are more readily absorbed.61 Dr Stephanie Wright and Professor Frank Kelly, King’s College London, states:
Given the novelty of this research area, there is a lack of information concerning the post-ingestion particle and chemical toxicity of micro and nanoplastics in humans. If micro and nanoplastics are capable of bioaccumulating, they present a long-term source of chemicals to tissues and fluids. This is of concern as some additives […] have human health effects.62
24.Microplastics are typically reported in the gut of marine organisms. In many food uses the gut is removed prior to consumption.63 Shellfish are exceptions and one recent study by Van Cauwenberghe et al., (2015) suggested that consumption of large quantities of mussels could present an exposure pathway.64 However, these studies have not yet shown measurable harm.65 DEFRA highlighted that no studies have investigated whether microplastics can be unintentionally ingested by humans and subsequently transported into tissues.66 They further state:
Even for high level consumers of seafoods that are most likely to be relatively highly contaminated with marine microplastics, such as mussels or crab, dietary exposure to microplastic particles is likely to be relatively low compared with inhalation of microplastics.67
We heard that if someone eats six oysters, it is likely they will have eaten 50 particles of microplastics.68
25.Several NGOs told us a precautionary approach should be applied to reduce the risks to human health arising from microplastics.69 The EIA state:
There is a clear risk that marine microplastics in seafood could pose a threat to human health, however the complexity of estimating microplastic toxicity means that quantification of the risks is not yet possible. […] Future studies should focus on assessing the fate and toxicity of microplastics in humans and assessing dietary exposure across a range of foods.”70
26.There is little evidence on potential human health impacts of microplastic pollution. What evidence there is suggests that dietary exposure is likely to be low. Further research in this area is underway and is clearly required. The Government should set out a timescale within which it will publish an assessment of the potential health impacts and any measures it intends as a response.
Economic consequences of microplastic pollution
27.There have been wide ranging estimates to the economic impacts of microplastics to the UK and EU. The MCS highlighted that marine litter can cause “serious economic damage that manifests itself as direct losses for coastal communities, tourism, shipping and fishing.”71 They state:
Potential costs across the EU for coastal and beach cleaning was assessed at almost €630 million per year, while the cost to the fishing industry could amount to almost €60 million, which would represent approximately 1% of total revenues of the EU fishing fleet in 2010.72
They add:
Sector costs could also be incurred if ingested microplastics affect commercial fish and shell fish stocks, or sales as the public become more aware of the issue and express concern through their shopping habits.73
These costs include the cost of clean-ups, loss of fisheries and wildlife, reductions in tourism, damage to vessels and the rescue costs and human health risks associated with damaged vessels.74 In the UK, World Animal Protection UK stated:
Municipalities spend approximately €18 million each year removing beach litter and in 2008 there were 286 rescues in UK water of vessels with fouled propellers; incurring a total cost of between €830,000 and €2,189,000.75
The EIA highlighted that estimates of the overall financial damage of plastics, without extrapolating the impact of microplastics, to marine ecosystems stand at US$13 billion each year.76 Dr Foster, Marine Conservation Society, highlighted that the large range of economic costs comes from including impacts on the shellfish and tourism industry.77 However, there are benefits to tackling microplastic pollution in the marine environment. The MCS estimated that £250 million pounds could be saved if microplastics were not present in the marine environment.78
28.CEFAS cited the MICRO project as the first attempt at defining economic impacts of microplastics on UK aquaculture (oyster) industry in the Channel region reported that it cost between £1,5M - £500M.79 The Government said:
There has been little assessment of the potential economic consequences of increased microplastics in the ocean. However an economic analysis demonstrated that there are potential costs associated with microplastics to the aquaculture sector in the UK. Removal of microplastics from the marine environment is currently considered to be prohibitively expensive and technically infeasible.80
The Government adds:
There is widespread agreement that the most effective way to reduce microplastic pollution is to focus on preventing plastic from entering the marine environment in the first place (both microplastics and larger pieces of debris that will eventually fragment into microplastics).81
Professor Richard Thompson highlighted the need for policy prioritisation. He stated:
There is limited information on the extent to which impacts vary according to the source or type of microplastic. […] more work would be needed to establish a risk assessment based on microplastic type, size or shape.82
He added:
On the basis of current knowledge it would be difficult to prioritise policy measures according to differences in the severity impacts according to microplastic type.83
29.The Committee heard that studies estimating the economic costs of microplastic pollution vary widely. As with the health impacts, the Government should set out a timescale in which it intends to produce a more accurate assessment. It should also ensure that microplastics are treated as an economic issue - within the scope of its food and farming strategy - as well as an environmental one.
International cooperation and future trends
30.The United Nations Sustainable Development Goal 14.1 is focused on ocean pollution.84 The Goals challenge countries over the next 15 years to take action to address critical issues including ocean plastic. International cooperation on tackling marine litter is also managed through a range of groups, conventions and legal instruments.85 According to DEFRA, the main ones are:
a)The EU Marine Strategy Framework Directive (MSFD): This is the overarching policy framework for addressing marine litter. A Technical Group on Marine Litter (TG-ML) provides guidance on targets, monitoring and measures.
b)MARPOL (the International Convention for the Prevention of Pollution from Ships): Annex 5 of the convention specifically deals with marine litter and prohibits the disposal at sea of all forms of plastic.
c)The Oslo and Paris Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR): A regional seas convention facilitating cooperation between contracting parties.
d)The G7 group: The UK also works with the other G7 countries to address marine litter.86
Thomas Maes, CEFAS, also highlighted ongoing research through the Joint Programming Initiative Oceans, which is European-led. He said:
They look at degradation of microplastics and plastics—how that happens. They also look at standardisation of techniques across the world and they look at impacts on animals.87
31.However, FFI argue that the non-governmental sector has taken the lead on international co-operation around microplastic pollution. They state:
The collection and public dissemination of microplastic data has been effective in driving corporate change and mitigating one of the most unnecessary inputs of microplastics to freshwater and marine environments.88
They also believe that an agreed monitoring framework for the mitigation of this source of microplastic is key to driving further industrial innovation in preventing microplastic emission.89 However, they add:
The NGO monitoring of these products and the companies that produce them–and the non-statutory funding that pays for this monitoring–are not sustainable in the long-term.90
32.Academic witnesses said a huge amount of research is currently taking place to try and ascertain the dangers of microplastics.91 This is a complicated and difficult task given the inherent complexities in biological systems and their interactions with the environment.92 However, they argued that there was progress. Dr van Sebille said, “even though there are lots of things we don’t know, we are very much on track to understanding this.”93 Similarly, Professor Kelly said, “I think it is a gradual accumulation of evidence and a realisation that [microplastics are] another thing we are doing to our environment that we really should not be doing.”94
33.It is important to address microplastic pollution as a transnational problem and to understand that plastic in the ocean is in constant motion. The Government should continue international cooperation despite uncertainties arising from the EU referendum. It is clear that international action is needed. We recommend the Government maintain existing cooperation with international partners in tackling microplastic pollution. Up to now, NGOs have taken the lead role in addressing this issue. However, this is unsustainable given the increasing costs and demands relating to microplastic pollution. As more evidence emerges about the impact of microplastic pollution, the Government must take on that role.
10 Plymouth Marine Laboratory (EIM0008), Royal Society of Chemistry (EIM0019), Environmental Investigation Agency (EIM0022), Brunel University (EIM0028), Professor Richard Thompson (EIM0053)
12 Marine Microplastic Pollution, POST Note 528, Parliamentary Office of Science and Technology, June 2016
13 Dr Natalie Welden (EIM0003), Plymouth Marine Laboratory (EIM0008), 5 Gyres Institute (EIM0017), Grantham Institute, Imperial College (EIM0027), Richard Shirres (EIM0031)
14 Q23
15 Q18
17 Marine Microplastic Pollution, POST Note 528, Parliamentary Office of Science and Technology, June 2016
19 Plymouth Marine Laboratory (EIM0008), University of Exeter (EIM0009), Marine Conservation Society (EIM0025), Brunel University, London (EIM0028), Thomas Stanton (EIM0033)
20 Q6
21 Q13
22 As above
25 As above
28 ‘Sources, fate and effects of microplastics in the marine environment: a global assessment’, GESAMP, 2015.
32 As above
35 Marine Microplastic Pollution, POST Note 528, Parliamentary Office of Science and Technology, June 2016
36 ‘Sources, fate and effects of microplastics in the marine environment: a global assessment’, GESAMP, 2015.
43 University of Exeter (EIM0009), Fauna & Flora International (EIM0016), Environmental Investigation Agency (EIM0022), Marine Conservation Society (EIM0025), Brunel University, London (EIM0028), DEFRA (EIM0034
44 Marine Microplastic Pollution, POST Note 528, Parliamentary Office of Science and Technology, June 2016
47 Q41
49 Marine Microplastic Pollution, POST Note 528, Parliamentary Office of Science and Technology, June 2016
51 Marine Microplastic Pollution, POST Note 528, Parliamentary Office of Science and Technology, June 2016
53 Fauna & Flora International (EIM0016), Royal Society of Chemistry (EIM0019), Brunel University, London (EIM0028)
55 Q349
56 Q361
57 King’s College London (EIM0014), 5 Gyres Institute (EIM0017), Environmental Investigation Agency (EIM0022), Marine Conservation Society (EIM0025), DEFRA (EIM0034)
60 Marine Microplastic Pollution, POST Note 528, Parliamentary Office of Science and Technology, June 2016
62 As above
67 As above
68 Q51
69 Q87, Q102, Q107, Q108, Q110
72 As above
73 As above
77 Q118
81 As above
83 As above
87 Q357
89 As above
90 As above
91 Q28, Q32, Q37, Q60
92 Q6
93 Q32
94 Q1
© Parliamentary copyright 2015
26 July 2016