Oct 27, 2019 | Global Documents |
Plastic Waste: Ecological and Human Health Impacts November 2011 Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 Contents Executive Summary 1 Introduction 3 1.0 Plastic Waste: Drivers and Pressures 4 2.0 State of Plastic Waste in the Environment 8 3.0 Impacts of Plastics Waste on the Health of Ecosystems 16 4.0 Responses 28 References 37 Figures 1. World Plastics Production 1950-2008. From Plastic Waste in the 4 Environment. 2. Continued decoupling of plastic waste and landfill 5 3. Main sources and movement pathways for plastic in the marine environment. 6 4. Proportion of post-consumer waste in EU-27, Norway and Switzerland according to function, 2008. 7 5. Composition and numbers of marine litter items found on beaches within OSPAR network. 8 6. Changes in composition of marine items found on beaches within OSPAR network 9 7. Algalita Research Centre monitoring 10 8. Litter ( items/ hectare) on the sea bed in the channel (x) and the gulf of Lion (y) 1998 -2010 11 9. Trends in the average number of marine litter items collected on reference beaches over three time periods 12 10. Identity and compostition of plastic debris collected from the strandline of the Tamar Estuary (UK) 12 11. Amount of user and industrial plastic in Fulmar stomachs in Netherlands over time 14 12. EcoQO performance in North Sea regions 2005-2009 and preliminary trends. Trend shown by connecting running average 5 year data 15 13. Trends in EcoQO performance in different regions of the North Sea since 2002 (by running 5-year average data) 15 14. Number and percentage of marine species with documented entanglement and ingestion records 16 Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 15. Relationship between BPA concentrations in leachate and per capita GDP of Asian countries 20 16. Illustration of additional effects of plastics in transport of phenanthrene 22 17. Concentrations of PCBS in beached plastic pellets 23 Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 Plastic waste is a growing concern and the drivers behind it look set to continue. Although recently there has been a slight decrease in plastic production, this is unlikely to be maintained. Plastic is a highly useful material and its applications are expected to increase as more new products and plastics are developed to meet demands. The increased use and production of plastic in developing and emerging countries is a particular concern, as the sophistication of their waste management infrastructure may not be developing at an appropriate rate to deal with their increasing levels of plastic waste. Management of waste in the EU has been improving in terms of recycling and energy recovery, but there is still much to be done. At the heart of the problem is one of plastic’s most valued properties: its durability. Combined with the throwaway culture that has grown up around plastic products, this means that we are using materials that are designed to last, but for short-term purposes. The state of plastic waste is notoriously hard to measure. It is estimated that in 2008 EU-27, Norway and Switzerland produced about 24.9 megatonnes of plastic waste (Mudgal et al., 2011) but its distribution is difficult to ascertain. This is especially so in the marine environment where the constant movement of the oceans, both horizontally on the surface and vertically within the water column, make it difficult to develop an accurate picture. Since the discovery of the Northern Pacific Garbage Patch, research has explored the gyres as areas of plastic waste accumulation, as well as beaches and river estuaries. There are a number of methods used to survey marine litter and currently there are initiatives to harmonise these. Several standardised surveillance guidelines have been developed, for example, those produced by the Oslo Paris Convention for Protection of the Marine Environment of the North-East Atlantic (OSPAR) and the United Nations Environmental Programme (UNEP). On land, there are few figures on the level of plastic waste and there is a need for more information on sources and possible pathways into the environment. There has been increasing concern about the presence of microplastics, which are generally defined as plastic fragments less than 5mm in size. These are produced either from the weathering of larger plastics or deposited directly as pre-consumer plastic or from use in abrasives, such as those used in some cosmetics. Microplastics are particularly difficult to monitor and they may also have more influential impacts than larger plastics. The impacts of plastic waste on our health and the environment are only just becoming apparent. Most of our knowledge is around plastic waste in the marine environment, although there is research that indicates that plastic waste in landfill and in badly managed recycling systems could be having an impact, mainly from the chemicals contained in plastic. In the marine environment, the most well documented impacts are entanglement and ingestion by wildlife. Other lesser- known effects are the alteration of habitats and the transport of alien species. Perhaps one of the most difficult impacts to fully understand, but also potentially one of the most concerning, is the impact of chemicals associated with plastic waste. There are several chemicals within plastic material itself that have been added to give it certain properties such as Bisphenol A, phthalates and flame retardants. These all have known negative effects on human and animal health, mainly affecting the endocrine system. There are also toxic monomers, which have been linked to cancer and reproductive problems. The actual role of plastic waste in causing these health impacts is uncertain. This is partly because it is not clear what level of exposure is caused by plastic waste, and partly because the mechanisms by which the chemicals from plastic may have an impact on humans and animals are not fully established. The most likely pathway is through ingestion, after which chemicals could bioaccumulate up the food chain, meaning that those at the top could be exposed to greater levels of chemicals. Plastic waste also has the ability to attract contaminants, such as persistent organic pollutants (POPs). This is particularly so in the marine environment since many of these contaminants are hydrophobic, which means they do not mix or bind with water. Again, the role of plastic waste in the impact of these toxic chemicals is unclear. Plastic could potentially transport these chemicals to otherwise clean environments and, when ingested by wildlife, plastic could cause the transfer of chemicals into the organism’s system. However, in some conditions plastic could potentially act as a sink for contaminants, making them less available to wildlife, particularly if they are buried on the seafloor. With their large surface area-to-volume ratio, microplastics may have the capacity to make chemicals more available to wildlife and the environment in comparison to larger sized plastics. However, once ingested, microplastics may pass through the digestive system more quickly than larger plastics, potentially providing less opportunity for chemicals to be absorbed into the circulatory system. Although plastic waste may not always cause detectable harm or death as an isolated factor, when combined with other impacts, such as uncontrolled fishing or oil spills, it may contribute cumulatively to serious impacts. These sub-lethal effects are difficult to monitor, but are nonetheless important to recognise. Research has indicated that some species or developmental stages are more vulnerable to ingestion of plastic waste and the toxic effects of the chemicals associated with it. Policy responses to plastic waste come in many forms and EXECUTIVE SUMMARY 1 Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 work on many levels, ranging from beach clean-ups to bans on plastic waste disposal at sea, to targets for waste management and recycling. Several market-based instruments have been explored such as deposit schemes to encourage the return and multi-use of plastics, and taxation on single-use plastics that do not fit into deposit return systems. However there has been little widespread application of these instruments and more research is needed to maximise their effectiveness and ensure they do not have secondary effects other than those intended. Plastic waste has the additional complication of spanning many policy areas, such as marine management, coastal management, waste management and the regulation of chemicals. This range of responses is necessary for such a global problem with such local variation, but to ensure plastic waste does not fall through the holes in the net of responsibility, there is a need to harmonise efforts and co- ordinate between different policy areas. A number of reports have called for better implementation of existing policy. The Marine Strategy Framework Directive has specified ‘marine litter’ as one of its descriptors of good environmental status and four indicators of this have been identified which can be applied to plastic waste. However, there may also be room for policy that is more specifically related to plastic waste, while still allowing for its connection to different policy areas. Lastly, there are a number of research gaps that need to be addressed to provide a stronger evidence-base on which to develop policy. Some of these are at the detailed level of impact, such as the actual levels of chemical exposure caused by plastic waste. Others are more action-orientated, for example, identifying potential hotspots where plastic waste is problematic, identifying high-risk products that use plastic or identifying wildlife and human groups that are more vulnerable to the impacts of plastic waste. However, the very nature of plastic waste as a fluctuating and mobile issue means that science is unlikely to be able to answer all the questions. It may be preferable to take policy action before waiting for a completely clear research picture to emerge so as to avoid the risk of impacts worsening and becoming more difficult to manage in the future. 2 Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 In the last 60 years, plastic has become a useful and versatile material with a wide range of applications. Its uses are likely to increase with ongoing developments in the plastic industry. In the future, plastic could help address some of the world’s most pressing problems, such as climate change and food shortages. For example, plastics are used in the manufacture of rotors for wind turbines and tunnels made from polyethylene can help crops grow in otherwise unfavourable conditions. As demand for materials with certain qualities increases, the plastics industry will aim to supply them. Meanwhile, increasing plastic production and use in emerging economies looks set to continue, and waste management infrastructure will have to develop accordingly. Unfortunately, the properties of plastic that make it so valuable also make its disposal problematic, such as its durability, light weight and low cost. In many cases plastics are thrown away after one use, especially packaging and sheeting, but because they are durable, they persist in the environment. If plastic reaches the sea, its low density means it tends to remain on the surface. Increasing attention has been paid to plastic waste by policymakers, scientists and the media and probably one of the most influential factors was the discovery of the Great Pacific Garbage Patch by Charles Moore in the late 1990s. This is a layer of rubbish floating between California and Hawaii that has been estimated to span about 3.43 million km2 (the size of Europe). It is mostly plastic and contains everything from large abandoned fishing nets to plastic bottles to tiny particles of plastic (or ‘microplastics’). This type of mass in the seas can be known as ‘plastic soup’ and there are concerns that Europe hosts similar patches, in areas such as the Mediterranean and the North Sea. As such, marine litter and plastic waste is a priority on the EU policy agenda. Plastic is still a relatively new material, which means the problem of plastic waste has only recently been realised, as has knowledge about its environmental persistence (Barnes et al., 2009). Even more recent is the discovery of possible health and environmental effects, such as the impacts of the chemicals contained in plastics. The monitoring of plastic waste and research into its impacts are still in their infancy, but so far the implications are worrying. The complexity of the issue is enhanced by the global nature of plastic waste and its constant movement, particularly at sea. This makes it difficult to confidently identify sources and scale up impacts from a specific location to create a global picture. The content of plastic waste can differ according to the location and time of year, while its impacts can vary between species and human life stages. So far, research has been somewhat piecemeal in documenting plastic waste’s distribution and impacts. To effectively inform policy, there needs to be more collation of existing data and greater harmonisation of research methods. This is also necessary to implement and monitor policy. This Science for Environment Policy In-depth Report on the human health and ecological impacts of plastic waste summarises and collates current research in this area. Using the Drivers Pressures State Impact Response (DPSIR) framework, it highlights major issues and concerns, as well as outlining questions around existing responses and possible strategies for the future. With the global nature of plastic waste, it is difficult to be precise about the Drivers and Pressures that bear influence and Section 1 combines the two and concentrates on measurement and monitoring. The sections covering State and Impacts concentrate on human health and ecological impacts. Finally, Section 4 deals with Responses to Plastic Waste and highlights current and future issues that need to be addressed, as well as knowledge gaps where more research is required to inform policy responses. 3 INTRODUCTION Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 In 2009, around 230 million tonnes of plastic were produced and around 25 per cent of these plastics were used in the EU (Mudgal et al., 2011). This global figure has been increasing by an average rate of 9 per cent since 1950 to a peak of 245 million tonnes in 2008, after which there was a slight drop in production. The financial recession may be responsible for this slight decline in plastic production, (PlasticsEurope, 2010 see Figure 1). About 50 per cent of plastic is used for single-use disposable applications, such as packaging, agricultural films and disposable consumer items (Hopewell et al., 2009). The drivers for plastic use are its improved physical and chemical properties compared to alternatives, its low cost and the possibility of mass production. Drivers for its reduction lie in a desire to minimise the use of resources (Kershaw et al., 2011). A life cycle analysis study has indicated that the use of plastics leads to significantly less energy consumption and emissions of greenhouse gases than the use of alternative materials (Pilz et al., 2010). In other words, plastic has surpassed other materials for certain functions and its comparative advantages may be increasing as technology improves. In addition, the increasingly short lifetime of products that use plastic, especially electronic goods, means that more plastic waste is being produced in today’s upgrade-and-dispose culture. A key example of this is the mobile phone: its plastic components contain several toxic substances (Nnorom & Osibanjo, 2009). Although these substances are not at levels to cause immediate risk, if quantities increase and end-of- life management is inadequate, such as the open burning often practised in developing countries, there is potential for environmental pollution and human health impacts. Production of plastic has levelled off in recent years, however, it is not declining and may well increase in the future as applications for plastic increase and its use continues to grow in developing and emerging economies (Global Industry Analysts, 2011). Without appropriate waste management, this will lead to increased plastic waste, which will add to the ‘back log’ of plastic waste already in existence. There is no agreed figure on the time that plastic takes to degrade, but it could be hundreds or thousands of years (Kershaw et al., 2011). Most types of plastic are not biodegradable. Some plastics are designed to be biodegradable and can be broken down in a controlled environment, such as landfill, but it is uncertain if this will occur under other conditions, especially in oceans where the temperature is colder (Song et al., 2009; O’Brine & Thompson, 2010). Even if plastic does eventually biodegrade, it will temporarily break into smaller fragments, which then produce so-called ‘microplastics’. These have a specific and significant set of impacts (see sections 3.4, 3.7 and 3.9). 4 1.0 PLASTIC WASTE: DRIVERS AND PRESSURES Figure 1. World Plastics Production 1950-2008. FromThe Compelling Facts about Plastic, PlasticsEurope (2009), p33. Box 1 Examples of the distribution of plastic waste • In 1992, a container ship lost 30,000 rubber ducks off the coast of China. Fifteen years later, some of these turned up on the shores of the UK (Maggs et al., 2010). • In 2005 a piece of plastic found in an albatross stomach bore a serial number traced to a World War II seaplane shot down in 1944. Computer models re-creating the object’s journey showed it spent a decade the Western Garbage Patch, just south of Japan, and then drifted 6,000 miles to the Eastern Garbage Patch off the West Coast of the U.S., where it spun in circles for the next 50 years (Weiss et al., 2006) • Van Franeker (2011) estimated that North Sea fulmars annually reshape and redistribute about six tons of plastic through ingestion of plastic waste. Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 1.1 Sources of plastic waste Plastic waste is a global problem, but with regional variability. This is particularly true of plastic waste in the marine environment, which can travel long distances, carried by currents or transported by wildlife, which ingest or become entangled in plastic. The EU’s Waste Framework Directive prioritises prevention in waste management. To develop effective prevention strategies, it is useful for policymakers to know the major sources of plastic waste and, if possible, which of these represent the greatest risk. Furthermore, to implement prevention-orientated policy effectively, meaningful monitoring of plastic waste is needed to assess the impact of policy. An example of this is the EU’s Marine Strategy Framework Directive (MFSD), which has established that Member States should take necessary measures to achieve or maintain good environmental status of marine waters by the year 2020. This requires monitoring and therefore the development of indicators of good environmental status. The MFSD has outlined 11 descriptors of environmental status, one of which is marine litter and identified four indicators for marine litter which, by default, also apply to plastic waste in the marine environment (see Box 2). A significant issue is that, while there is an abundance of data on debris in the marine environment, there is a comparative shortage of data on plastic waste on land. This is despite the estimate that 80 per cent of plastic waste in the sea is from land-based sources (Sheavly, 2005). The main land- based sources of marine plastic waste include storm water discharge, combined sewer overflows, tourism related litter, illegal dumping, industrial activities e.g. plastic resin pellets, losses from accidents and transport, and blowing from landfill sites (Allsopp et al., 2006). The ocean-based sources tend to be commercial fishing, recreational boaters, merchant/military/ research vessels, losses from transport, offshore oil and gas platforms (Sheavly, 2005). A disproportionate amount of waste in the marine environment is plastic. Plastics make up an estimated 10 per cent of household waste, most of which is disposed in landfill (Barnes, 2009; Hopewell et al., 2009). However, 60- 80 per cent of the waste found on beaches, floating on the ocean or on the seabed is plastic (Derraik, 2002; Barnes, 2005). Waste management varies from country to country. One of the most instrumental EU waste management regulations is the Landfill Directive (1999), which sets targets for the diversion of biodegradable municipal waste from landfill, allowing Member States to choose their own strategies for meeting these targets. However, there are no specific targets for diversion of plastic waste. An EEA review (Herczeg et al., 2009) of the Directive in five EU countries and one sub-national area (Estonia, Finland, the Flemish Region of Belgium, Germany, Hungary and Italy), indicates that there has generally been a drop in the amount of waste going to landfill from 1999-2006. Separate data from a PlasticsEurope report (PlasticsEurope, 2009) indicate that, despite a 3 per cent annual growth in the past decade for post-consumer plastic waste in EU15, landfill amounts have increased by only 1.1 per cent per year (see Figure 2), thanks to increases in recycling and energy recovery. Sources of plastic waste vary by region, for example, shipping and fisheries are significant contributors in the East Asian Seas region and the southern North Sea (Kershaw et al., 2011), whereas tourism is a major source in the Mediterranean. Plastic waste accumulates in certain areas of the sea, such as gyres, which are large rotating currents, which have lower sea levels near their centres. There are five major gyres in the world: the North Pacific, the South Pacific, the Indian Ocean, the North Atlantic and the South Atlantic. These act as accumulation zones for marine debris, which is forced into the centre where winds and currents are weaker (Moore et al., 2001). Currents, wave action, and the nature of the continental shelf and seafloor also affect the distribution of plastic waste. Harbours and estuaries near urban areas tend to attract large amounts of plastic waste from recreation and land-based sources, while more remote beaches tend to be littered with fishing debris (Derraik, 2002). This is supported by findings from a study in a conservation area in north-eastern Brazil (Ivar 5 Figure 2. Continued decoupling of plastic waste and landfill. From The Compelling Facts about Plastic, PlasticsEurope (2009) p11. Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 do Sul et al., 2011) which indicated that 70 per cent of debris on populated beaches comes from local sources, mainly tourism activities, while on unpopulated beaches, non-local sources account for 70 per cent of plastic waste, mainly from fishing and domestic activities, such as household waste from rivers and onshore, as well as waste from transiting ships. Although it is important to try and determine sources of plastic waste for developing and monitoring policy, it should be remembered that the distinction between land-based and sea-based sources is irrelevant for prevention, as all plastic is produced on land. If we are to reduce overall amounts of plastic waste, the land is where the greatest efforts need to be made. 1.2 Categories of plastic waste Categorisation can help us understand plastic waste and identify sources. However, most classifications have a purpose and waste is often categorised with a specific goal in mind. For example, a waste classification designed to support a recycling programme would identify commonly recycled plastics (Barnes et al., 2009). Classification can also depend on policy, for example, Moore et al. (2011) conducted a study on plastic debris in two Californian rivers that categorised pieces as below or above 4.5mm, because Californian law defines rubbish as being 5mm or greater. One of the most fundamental categorisations is into pre- and post-consumer plastic waste. Pre-consumer plastic waste is produced during manufacturing or converting processes, while post-consumer plastic waste is produced after a product is consumed or used. Pre-consumer plastic waste often consists of small pellets that are used to make larger plastic objects. Many statistics are concerned with post-consumer plastic waste. In 2008, the EU-27, Norway and Switzerland were estimated to generate a total of 24.9 megatonnes of post-consumer plastic waste (PlasticsEurope, 2009). This was further categorised according to function. (See fig. 4) At sea, plastic waste is often categorised into macro- (over 20mm diameter), meso- (5-20mm diameter) and micro- (under 5mm diameter) plastics. Very small microplastics are barely detectable, and for practical purposes, microplastics are usually defined as those that range from 5mm to 333 micrometres (µm). Practically, this is the lower limit because 333µm mesh nets (‘Neuston nets’) are commonly used for sampling (Arthur et al., 2009). However, methods, such as ‘Fourier Transform infrared spectroscopy’, can detect particles less than 1.6µm. Macroplastics can be further categorised according to type of object, for example, bottle, bag or lid. 1.3 Microplastics: sources and categories Microplastics are a significant issue in plastic waste, partly because they are more difficult to monitor, and partly because they may have greater impacts at a chemical and physical level on ecosystems and human health, owing to their size and large volume-to-surface area ratio. In the ocean as well as on land, plastics tend to fragment into smaller particles. This can be aided by the action of ultraviolet (UV) radiation, waves and wind. In landfills, leachate acidity and chemicals can break down plastics. In the sea, water absorbs and scatters UV so plastics floating near the surface will break down more rapidly than those at depth. For those on the seabed, breakdown is significantly slower since there is no UV radiation and temperatures are colder. 6 Box 2 MSFD indicators of marine debris to measure good environmental status: 1. Trends in the amount, distribution and composition of marine debris on coastlines. 2. Trends in marine debris in the column and deposited on seafloor. 3. Trends in the amount, distribution and composition of micro particles (mainly microplastics) 4. Trends in the amount and composition of marine debris ingested by wildlife. Figure 3. Main sources and movement pathways for plastic in the ma- rine environment. (from UNEP Year Book, Kershaw et al., 2011) Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 Plastic fragments can also come from the use of plastic particles as abrasives in ‘sandblasting’ and exfoliants in cosmetics (Barnes et al., 2009; Andrady, 2011), from spillage of pre-production plastic pellets and powders used for moulding plastic objects, as well as from plastic items deliberately shredded on board ships to conceal plastic waste in food waste (Barnes et al., 2009). These sources are known as primary microplastic sources, whereas secondary microplastics are those formed from breakdown of larger plastic material (Arthur et al., 2009). The relative importance of primary and secondary sources of microplastics to the environment is unknown and addressing this gap could help inform measures to mitigate and prevent microplastic pollution (Arthur et al., 2009). Andrady (2011) provides a comprehensive review of the degradation processes of plastics under marine conditions and the origin of microplastics. The review raises the concept of nanoplastics. These are engineered plastic nanoparticles derived from post-consumer waste via degradation. Although they have not been quantified yet the review suggests there is little doubt that weathering of plastic can produce nanoscale particles, which could potentially be easily absorbed by phytoplankton and zooplankton (Andrady, 2011). Another potential secondary source of degradation into microplastic is through digestion by wildlife, which also transport plastic waste. Van Franeker (2011) suggest that fulmars (a type of seabird) reduce the size of plastic particles in their muscular stomach and excrete them back into the environment in the form of microplastics. They estimate that fulmars reshape and redistribute about 630 million plastic particles every year, representing about six tons in plastic mass. 7 Figure 4. Proportion of post-consumer waste in EU-27, Norway and Switzerland according to function, 2008. From Plastic Waste in the Envi- ronment, Mudgal et al.(2011) Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 As production and use of plastic has increased over the years, a large amount of plastic waste has accumulated in the environment. As a durable material, it is also persistent. Recycling and recovery rates may be improving, but the actual amount of plastic waste produced remains roughly the same and adds to existing waste. There is little information on the amounts, rates, fate or impacts of plastic waste on land, whereas there has been a major effort to quantify impacts on shorelines and sea (Barnes et al., 2009). If it is not recycled or recovered, most plastic waste is disposed of in landfill sites where, although not visible, it may still come to the surface as ‘debris’. In addition, the conditions within landfill may cause the chemicals contained within plastic to become more readily available to the environment (see section 3.6). This is a particular concern in developing countries where landfill management is not as closely monitored as in the EU. 2.1 Between land and sea - Monitoring plastic waste on coastlines Although it is difficult to determine source and type of plastic at sea, particularly if it is weathered or partially degraded by sunlight, there are several methods to monitor plastic waste in the marine environment, including beach surveys, surveys at sea and monitoring species affected by plastic waste. Beach surveys vary in their sampling protocols. For example, they can record the number of items and/or the mass of waste, and can differ in the areas covered and whether they include buried litter. There is debate on whether standing ‘stocks’ of plastic waste should be recorded, i.e. snapshots of plastic waste at points in time, or rates of accumulation, i.e. how much plastic waste accumulates per unit of time. The latter requires an initial clean-up of the area, which is difficult, particularly for microplastics. Plastic waste monitoring is usually embedded in the monitoring of general marine litter. The OSPAR (Oslo Paris Convention for Protection of the Marine Environment of the North-East Atlantic) Pilot Project on Monitoring Marine Beach Litter in the North Sea was one of the first region-wide projects in Europe to develop a standard method to monitor marine litter found on beaches. It identified the sources and quantitative trends in marine litter on the beaches of nine countries within the OSPAR network. This confirmed that the predominant type of marine litter is plastic. On the Greater North Sea coast, plastic dominated with the highest levels in the north where it made up 80 per cent of beach litter; on average there were 900 items of litter per 100m of beach. Lower percentages of plastic were found further south, where it made up 75 per cent of items on the Southern North Sea coast (out of 400 items per 100m), 70 per cent on the Celtic Sea Coast (out of 650 items per 100m) and 62 per cent on the Iberian Coast and Bay of Biscay (out of 200 items per 100m) (OSPAR, 2007). These plastic items were classified according to type (see Figure 5), with plastic/polystyrene pieces smaller than 50cm dominating. Overall quantities of plastic waste on OSPAR beaches fluctuated between 2001 and 2006 with no discernible pattern. The composition of the plastic waste also changed, particularly for plastic/polystyrene (see Figure 6). It is difficult to find a consistent trend over time for plastic waste both on beaches and at sea. This lack of pattern is likely to be partly because plastic debris in the marine environment is always moving. Barnes and Milner (2005) found no consistent trend in general debris in northern hemisphere shores, but there were increasing densities throughout the 1980s, 1990s and early 2000s in the southern hemisphere with the highest increases at high southern latitudes. More recent data (Barnes et al., 2009) suggests that patterns of debris accumulation may be stabilising on islands (those considered were South Orkney, South Georgia and NW Hawaii). A relatively new survey method combines the use of aerial photography and in situ measurements. This calculates the mass 8 2.0 STATE OF PLASTIC WASTE IN THE ENVIRONMENT Figure 5. Composition and numbers of marine litter items found on beaches within OSPAR network. From Marine litter Preventing a Sea of Plastic (2009), OSPAR Convention Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 of litter per unit area using a sample and then combines it with balloon-assisted photography to define the area covered by litter. On an island beach surveyed in Japan, the mass of litter was calculated to be 716 kg, 74 per cent of which was plastic (Nakashima et al., 2011). Despite being measured by weight, 55 per cent of the plastic waste was light plastic. Polyethylene was the most common type found and the study suggested further research is needed to determine if lighter plastics, such as polyethylene, are more readily transported by winds and currents than heavier plastics, such as PVC which tends to sink and so is subject to different patterns of transportation than plastic on the surface. From -their pilot project, OSPAR have developed a set of guidelines for monitoring marine litter on beaches (OSPAR, 2010a) that sets out recommendations on selecting reference beaches, sampling, timing and identification of litter. As part of Cheshire et al.’s (2009) UNEP/ IOC Guidelines on Survey and Monitoring marine litter, there is also a set of operational guidelines for comprehensive beach litter assessment. More informally Ryan et al. (2009) have set out best practices for beach surveys (see Box 4). 2.2 The marine surface - monitoring plastic waste floating at sea Surveys at sea are more costly and challenging than beach surveys and can only assess standing (or floating) stocks rather than accumulation rates, because it is impossible to perform a complete clean-up. Amounts of floating debris can be estimated either by direct observation or by net trawls. Most observation surveys are conducted from ships or small boats. Aerial surveys have also been used which have the advantage of covering large areas but the disadvantage of only detecting large items of waste (Ryan et al., 2009). In 2008, an assessment prepared by MED POL (the marine pollution assessment and control component of the Mediterranean Action Plan) reported finding 2.1 items of general debris per km2 floating in the Mediterranean Sea (observation with binoculars) and 83 per cent of this waste was plastic (UNEP, 2009). All observation surveys suffer discrepancies between individual observers (inter-observer variability), but variability can also occur for other reasons, such as meteorological conditions, ocean currents and the constant movement of plastic waste. For example, in a visual survey of general debris conducted in the northwestern Mediterranean 15-25 items per km2 were reported in 1997, and just 1.5-3 items per km2 were reported in 2000 (Aliani et al., 2003). In general, net-based surveys tend to be less subjective. Most research has been done using Neuston or Manta trawl nets, which have a small mesh (usually 0.3mm, and small net opening and thus focus on microplastics). Manta trawls have been used to sample and characterise the large gyre systems in the oceans with elevated amounts of clustered marine litter (Pichel et al., 2007). One of the most well known research programmes that use this method is the Algalita Centre, which regularly monitors the North Pacific Subtropical Gyre (see Figure 7). In 1999, they reported just under 335,000 items of plastic per km2, weighing 5.1 kg per km2 (Moore et al., 2001). 9 Figure 6. Changes in composition of marine items found on beaches within OSPAR network. Diagram from Marine Litter Preventing a Sea of Plastic (2009) OSPAR Commission Box 3 Local variability in plastic waste A study in Portugal (Frias et al., 2011) researched plastic debris on mainland coasts. This found that out of 9655 plastic items identified from 10 beaches, about 85 per cent were plastic fragments, plastic pellets and styrofoam. There was a decrease in volume of plastics from north to south, probably because north-south main currents carry and deposit plastic debris from both land-based and sea-based sources. Box 4 Best practices for beach surveys of plastic waste, Ryan et al (2009) • Record litter from the sea-edge to the highest area at the top of the beach where debris is deposited (strandline) • Record both the mass and the number of items of plastic waste • Categorise according to composition and function • Ideally sample across a network of sites • Sampling of meso-debris should be done with a combination of methods Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 Investigation into the physical and chemical composition of plastic waste is limited, although there has been a recent study of the composition of plastic debris in the western North Atlantic Ocean (Moret-Fergusson et al., 2010). This found that more than 88 per cent of particles were less than 10 mm in length and 69 per cent measuring between 2 and 6 mm. Over time the percentage of smaller sized particles has increased. In the 1990s, 16 per cent of plastic particles were 10mm or larger, while in a more recent study period, only 6 per cent were 10 mm or larger. This could indicate that mechanical abrasion and photochemical breakdown are causing plastic particles to decrease in size. Secondly, the study indicated that the density of plastic particles on coastlines was similar to that of virgin plastics i.e. the plastic had changed little from its original form, whereas at sea the density of plastic particles were greater, indicating a change from its time at sea. This was thought to be due to biomass accumulation on the plastic or biofouling, which is likely to increase the density of the plastic. The researchers suggest that data on particle density could help us understand what types of plastics are sinking or floating and the potential impact of plastics on wildlife. Methods to ascertain composition of plastics tend to rely on ‘Fourier transform infrared spectroscopy’. However, Moret-Fergusson et al. (2010) suggest that this technology is scarce and expensive, and propose a simpler alternative for establishing composition, which analyses the amount of carbon, hydrogen and nitrogen in plastic. This method may be cheaper, but it is not as accurate and requires combusting samples of plastic. Infrared spectroscopy methods are under further development and may become cheaper in the future. 2.3 Monitoring plastic debris in rivers and estuaries Studying plastic waste in rivers and estuaries could prove useful in trying to identify sources. Browne et al. (2010) investigated the composition of plastic debris on the banks of a UK estuary from both the surface and the underlying 3cm of sediment. Out of the 952 items found, microplastic (less than 1mm) accounted for 65 per cent of debris and mainly (80 per cent) consisted of the denser plastics such as PVC, polyester and polyamide. Macroplastics tended to be less dense. There are a number of possible explanations for this. For example, it could be that denser plastics are more likely to suffer weathering as they are in contact with abrasive particles in sediment, or it could be that denser microplastics are easier to distinguish from the sediment so appear to be more abundant. The research found a larger amount of microplastics at the more exposed sites towards the mouth of the estuary where debris is likely to experience strong wave- action and abrasion. Another possible source is the discharge from sewage treatment, as domestic laundry may act a source of fibres or microplastics. Galgani et al. (2000) suggest that strong currents in large rivers may transport litter offshore while in the smaller rivers, where currents are weaker, the litter tends to become beached in the estuaries. As existing research indicates, there is much speculation about the reasons for the composition and distribution of plastic debris and much still needs to be done on the major influences to identify where policy can be effective. Moore et al. (2011) studied quantity and type of plastic debris from two urban rivers to coastal waters and beaches in Southern California. Using nets in the rivers they found 2.3 billion pieces over 72 hours, which weighed 30,500 kg. The majority were foams, such as polystyrene (71 per cent), followed by ‘miscellaneous fragments’ (14 per cent), pre-production pellets (10 per cent) and whole items (1 per cent). 81 per cent of all plastics were between 1 and 4.75 mm (the size above which California officially classifies them as rubbish). The study suggests more systemic monitoring could provide a picture of how much debris is being transported by rivers, which in turn could provide a baseline to support decisions by policymakers on how to prevent plastic entering rivers. 2.4 Monitoring plastic waste in the water column and on the seafloor Most studies tend to sample floating plastic debris, but it is also important to monitor suspended plastic and plastic on the sea bottom. Bongo nets can be used to sample suspended debris, while trawl surveys, scuba diver surveys, and submarine vehicles can be used to sample plastic waste on the sea bottom. Data from the KIMO (Kommunenes Internasjonale Miljøorganisasjon) ‘Fishing for Litter’ activities organised by national governments in the Netherlands, Scotland and the United Kingdom found that plastic made up a large percentage of marine litter on the seabed. For example, in Scotland 55 per cent of the 3464 items of marine litter recovered (which made up 117 tonnes in weight) were plastic (KIMO, 2008). In their study of benthic marine litter, Galgani et al. (2000) found relatively lower percentages of plastic in the Celtic Sea, the Baltic Sea and the North Sea (30 per cent, 36 per cent and 49 per cent, respectively) while 10 Figure 7. Algalita Research Centre monitoring. Weight density refers to the total weight of plastic particles found per cubic metre of water. The larger the circle on the map, the greater the weight of plastic particles found at that particular site. Plastic Waste: Ecological and Human Health Impacts Science for Environment Policy | In-depth Reports | Plastic Waste: Ecological and Human Health Impacts November 2011 in the north-western Mediterranean, the East English Channel and Bay of Seine, the percentages were higher (77 per cent, 85 per cent and 89 per cent, respectively). The figures are most concerning for the north-western Mediterranean where the level of litter is much higher than other regions at just under 20 items per hectare (ranging between 0 and 78 items), which means there are, on average, 15 items of plastic waste per hectare, most of which are plastic bags. Other regions had between 1 and 6 items of marine litter per hectare. As well as regional variability, there was also seasonal variability, for example, in the Bay of Biscay there are approximately two items of marine litter per hectare during the summer and 14 items per hectare in winter. Most of the items were plastic (92 per cent) and out of those, the majority (94 per cent) were plastic bags. The densely populated coastline, shipping and limited tidal flow or water circulation which traps the bottom debris may be responsible for the large amounts of plastic waste in Mediterranean sites. High sediment accumulation also tends to trap plastic. Large rivers are responsible for inputs of plastic debris to the seabed and collections are often found around the river mouth. At a smaller scale, there is a high concentration of plastic around rocks and in channels or canyons, particularly on the continental shelf (Galgani et al., 1996). As most polymers degrade through exposure to UV radiation, it is likely that plastic on the sea floor will be even more persistent than that on the surface or on the beach. Just as plastic waste moves on the surface of the sea and from the sea to the coast, it can also move vertically. So-called ‘biofouling’ or accumulation of micro-organisms, plants or algae onto plastic debris causes it to become heavier and eventually sink. In their sample of plastic debris in the western North Atlantic Ocean, Morét-Ferguson et al. (2010) found that the range in specific gravities (specific gravity is the ratio of the plastic density to the density of water) was 0.808 to 1.24 grams per milliliter. This range was greater than most virgin plastics and indicated that the plastics had been subject to fouling. They also found that the plastic in the sea had a different specific gravity to plastic debris found at the beach, suggesting that plastic undergoes changes when it is at sea. Lobelle and Cunliffe (2011) investigated the formation of films of micro-organisms (biofilms) on plastic waste in the sea and found that films developed rapidly and were visibly apparent after one week. By three weeks, the plastic started to sink below the surface. These data could help identify what types of plastic are floating or sinking, and which are therefore potential hazards for either surface-feeding or seafloor-feeding wildlife. Establishing the size, mass and composition of plastics that persist in the ocean is important for understanding the impacts of plastics (Morét-Ferguson et al., 2010) 2.5 Trends in plastic waste over time It is difficult to find any clear patterns in the quantities of plastic waste over time. In some regions, and over some timescales, there appears to be an increase, whereas in others there may be a short-term decline and then stabilisation. This is evidenced by the findings from the OSPAR survey (see Figure 9). As yet, no studies have found evidence of a continuing decline in the quantity of plastic debris in the oceans over time and the majority of studies show considerable variability between sampling dates and therefore give little evidence of temporal trends. The monitoring data we have is mostly from beaches or surface waters. There is evidence that plastics are sinking from the sea surface to the seabed with substantial quantities observed by submersibles, there are also reports of plastic debris accumulating beneath the surface in beach sediments. Hence movement of debris away from the compartments that have traditionally been monitored will also influence our ability to detect underlyi
While plastic has many valuable uses, we have become addicted to single-use or disposable plastic — with severe environmental consequences. Around the world, one million plastic drinking bottles are purchased every minute, while up to 5 trillion single-use plastic bags are used worldwide every year. In total, half of all plastic produced is designed to be used only once — and then thrown away. Researchers estimate that more than 8.3 billion tonnes of plastic has been produced since the early 1950s. About 60% of that plastic has ended up in either a landfill or the natural environment.
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