Scientific Knowledge

General Explanation

 

There is still a lack of reliable data and short of scientific knowledge on marine plastic debris. Although we should take some actions, based on the precautionary principle, we also need to enrich scientific knowledge in various fields, such as monitoring method, flow of macro- and microplastics in the ocean, impact of to ecosystem and human health, material flow analysis, life cycle assessment, and others. RKC-MPD is planning to organise some seminars and working groups to review the current status of relevant research and to facilitate future research in the region.

Life Cycle Assessment

 

Life Cycle Assessment (LCA) is a tool to assess the potential environmental impacts of any stage in life cycle of products or services, from extraction of resources, production, consumption, to reuse, recycling, or final disposal. In the context of combatting marine plastic debris, reducing the use of plastic is essential to prevent leakage from the source. However, some LCA research on plastics and plastic products indicate that replacing plastics with alternative materials is not always an environmentally friendly choice, at least when it comes to climate change impact.

Ayudhaya (2014) compiled some comparisons that emphasise that plastics are still essential to address climate change. Chaffee and Yaros (2014) found that conventional polyethylene bags are more environmentally friendly than paper bags and compostable bags, especially in terms of fossil fuel use, municipal solid waste, greenhouse gas (GHG) emission, and freshwater use. Huang and Ma (2004) revealed that almost all kinds of plastic packaging have significantly less environmental impact than aluminium, glass, steel, and cardboard packaging. The ban on plastic bags was not effective in reducing GHG emission, especially in municipalities where they have been reused and recycled (Nishijima and Nakatani, 2016). Municipalities should find alternative products or materials for disposing of their waste or provide materials for recycling instead of plastic bags.

The Plastic Circulation Cooperation in Japan found that the use of plastic packaging in distributing fruit (peaches and strawberries) is efficient in reducing the amount of fruit damaged as a result of vibration in distribution trucks (Plastic Circulation Cooperation, 2017). Plastic packaging reduces food loss and environmental loads (GHG emission and energy consumption). For example, in an average distribution distance of 324 km, food loss from plastic-packaged fruit was only 0.1%, compared with 73.4% of fruit without plastic packaging. As for impacts, plastic-packaged fruit reduced 69% of GHG emissions and 66% energy consumption.  

Future studies should assess more comprehensive impacts along the life cycle of plastics, focusing not only on GHG emissions and energy consumption but also end-of-life impacts, such as littering potential, human toxicity, and aquatic ecotoxicity. To promote such research, national LCI database should be well established and developed to reduce any bias and ensure accuracy and applicability of assessment. Thailand has been developing its LCI database for 20 years: introducing life cycle thinking (since 1990), capacity building on human resources (since 2002), establishing the database and its master plan (since 2004), promoting its application (since 2010), improving data quality (since 2013), and developing a software (since 2015) (Gheewala, 2018).

Globally, studies have been conducted to better utilise LCA, especially to tackle the emerging marine plastic debris issue. As LCA was originally developed for impact assessment of land-based industries on mainly terrestrial and freshwater ecosystems, impact indicators for major drivers of marine ecology (i.e. sensitivity of marine biota with plastic debris at community and ecosystems scales) are less developed (Woods et al., 2016). To fill the gap, a specific framework to assess marine plastic debris impact was developed (Verones et al., 2020) (Figure 1). The framework considers three categories of plastic: macro (>5 mm), micro (<5 mm), and nano (<1 µm). Each category can end up in air, terrestrial, freshwater, or marine compartments, and possibly move between compartments. Different compartments will generate different exposure pathways and cause varied effects depending on the receptors. Nano-plastics could be toxic to humans if inhaled. Together with micro-plastics, nano-plastics could be ingested by invertebrates and vertebrates in terrestrial and freshwater compartments, which could be toxic to humans if they ingest such animals, create ecotoxicity, have physical effects on biota, and affect invasive species. In the marine compartment, macro-plastics are exposed through entanglement and accumulation that could disrupt socio-economic as well as natural and cultural values of tourism sites such as beaches, coral reefs, or landscapes. The framework clearly indicates the damaging impacts of marine plastic debris, not only on ecosystem quality but also on human health as well as on socio-economic and cultural values.

Figure 1. Framework for Marine Plastic Debris Assessment in LCA

Source: Verones et al. (2020).

Sonnemann (2018) highlighted the integration of holistic life cycle thinking into business practices. Current businesses create products based on the exclusive consideration of environmental impacts. For instance, businesses often end up choosing plastic bottles instead of steel cans or glass bottles for packaging, based on limited environmental indicators. Adopting the comprehensive LCA in the entire business will show the wider environmental impacts and a truly environment-friendly product. Vázquez-Rowe (2018) discussed the unmapped marine debris impacts during LCA of the marine ecosystem conducted by Langlois et al. (2014). Vázquez-Rowe (2018) mentioned the urgent need to consider micro-plastics impacts due to direct littering in the marine ecosystem, including human toxicity from seafood, ecosystem quality impacts on the different trophic levels such as seabirds, and loss of resources and revenue.

Such global efforts will inspire similar efforts to better utilise LCA in combatting marine plastic debris, especially in ASEAN countries. Such efforts will consider plastics in their entire life cycles in a more holistic way, rather than exclusively measuring the indicators of GHG emissions and energy consumption. Considering the damaging impacts of plastic on human health as well as on socio-economic and cultural values will enrich the state of understanding on the LCA of plastics. In the future, such holistic life cycle thinking will be applied to business at all levels.

References

Chemical Impacts of Plastics on the Marine Ecosystem

 

In 2015, global plastic production reached 322 million metric tonnes. Light, durable, and flexible, plastic has become popular over time due to its low production cost. With increased production and consumption of plastic, concerns about its effects on the marine environment started to emerge due to its long-term chemical stability in the oceans (Andrady and Rajapakse, 2017). Plastic in the oceans is fragmented into smaller pieces by UV radiation, which, in turn, are ingested by marine organisms, causing wounds, ulcerating sores, blockage of digestive systems, and, in extreme circumstances, ruptured bladders of marine species such as turtles. Ingestion of large amounts of plastic can create a false sense of fullness while slowing the rate of digestion (Ryan, 2016).

Three types of toxicity from plastic pose threats to the environment: additives mixed during processing and fabrication of products, residual monomers or catalysts trapped in the resin, and chemicals picked up by plastics from the environment. Of the three, additives are found to have the highest concentrations in plastic products. These include fillers, plasticisers, flame retardants, colorants, UV stabilisers, thermal stabilisers, and processing aids (Table 1).

Table 1. Types of Additives in Common Plastic

Class of additives

Functions

Examples

Fillers

Reinforcement; reduce cost

Clays, silica, glass, chalk, alumina, asbestos, rutile

Plasticisers

Soften polymer to make it flexible and extensible

Di-n-octyl phthalate, other phthalates

Flame retardants

Prevent ignition and/or flame propagation

Poly (bromo diphenyl ethers), alumina, phosphites

Colorants

Impart desired colour to product

Cadmium, chromium, lead, cobalt compounds

UV stabilisers

Control degradation of plastic regularly exposed to solar radiation

Hindered amine light stabilisers, benzo-phenone light-absorbing compounds

Thermal stabilisers

Control degradation during processing

Diakyl maleates, diakyl marcaptides

Processing aids

Ease processing of polymer

Waxes, oils, long-chain esters of polymeric alcohols

Others (anti-statics, biocides, odorants)

Obtain desired property in product

 

Source: Andrady and Rajapakse (2017).

Plastic in oceans retains additives, which are then directly transferred to marine organisms through prey ingestion. Indirect toxicity results when additives not chemically bound to the plastic are released into the environment and become available to organisms (Hermabessiere et al., 2017).

The most common additives found in marine debris are brominated flame retardants (BFRs) , phthalates, nonylphenols, bisphenol A (BPA), and antioxidants.

1. BFRs

Generally, BFRs are potential endocrine disruptors. Organisms exposed to endocrine disruptors will suffer in multiple developmental, reproductive, neurological, immune, and metabolic diseases (Ingre-Khans, Ågerstrand, and Rudén, 2017). BFRs are used in plastic products such as electronic devices and insulation foams to reduce flammability. The additives cover a range of chemicals, including the most commonly used additives in plastic industry, such as polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane, and tetrabromobisphenol A. Research shows that some types of BFRs are not chemically bound to polymer matrix, thus causing them to leach into the environment. Some commercial formulations of BFRs, called penta-, octa-, and deca-brominated diphenyl ethers (BDEs), are ubiquitous, harmful, stable, and bioaccumulate in the environment, with detrimental impacts on human health. Penta- and octa-BDEs have been banned in the European Union (EU) since 2004. The EU also banned deca-BDE for electronic and electrical applications in 2009 (European Commission, 2003; European Council Decision, 2009). Japan has  banned production and importation of tetra- and hepta-BDEs since 1995 (Covaci et al., 2008).

Besides being regulated under the European Council Decision in 2009, several types of BDEs have also been controlled by the Stockholm Convention since 2004. The convention prohibits persistent organic pollutants, which include deca-, hexa-, hepta-, tetra-, and penta-BDEs. Many countries in Southeast Asia and East Asia, including Japan, China, the Republic of Korea, Cambodia, Indonesia, the Lao People's Democratic Republic, Myanmar, the Philippines, Singapore, and Thailand, have ratified the convention (Stockholm Convention, 2019a). Under the regulation, deca-BDEs in plastic housing and parts used for heating home appliances are allowed at concentrations lower than 10% by weight (Stockholm Convention, 2019b). Although the convention does not set allowances for hexa-, hepta-, tetra-, and penta-BDEs, these have to be recycled through an environmentally sound mechanism, they are not allowed to be exported if their concentrations exceed the standard in the territory of the involved party, and their use must be under control of relevant stakeholders (Stockholm Convention, 2019c; Stockholm Convention, 2019d).

In 2003, the EU adopted the Restriction of Hazardous Substances (RoHS) Directive 2002/95/EC, which restricts the use of hazardous substances in electrical and electronic equipment. PBDEs are amongst the prohibited substances. The directive notes that PBDEs can be used only at 0.1% concentration by weight since they affect the endocrine system (RoHS Guide, 2020). Some Southeast Asian and East Asian countries have adopted a similar approach regarding PBDEs. For instance, China’s Requirements for Concentration Limits for Certain Restricted Substances in Electrical and Electronic Products SJ/T 11363-2006 states that PBDE concentration (deca-BDE not included) in products should not surpass 0.1% by weight. In general, China has regulations on PBDEs, such as the Ordinance on Management of Pollution and Control of Pollution from Electronic Information Products in 2007 and the Administrative Measures on Pollution Prevention of Waste from Electrical and Electronic Equipment in 2008 (revised in 2016) (Ni et al., 2012; Chem Safety Pro, 2019). Weak enforcement of those regulations, however, remains an issue (Ni et al., 2012). Viet Nam and Singapore allow the use of PBDEs with as much as 0.1% concentration by weight in electric or electronic products (Government of Viet Nam, 2011; Government of Singapore, 2020). As Thailand has no strong legal frameworks that control the use of PBDEs, they are found in some products, including electronics, furniture, and car seats. However, some types of BDEs (47, 99, 153, 175, and 183) will be added to the Thailand Hazardous Substances List, which is annexed to the Notification of Ministry of Industry on List of Hazardous Substances (No. 4) (Muenhor and Harrad, 2018). Malaysia also prohibits the use of PBDEs in parts of lighting equipment based on MS 2237:2009, which restricts certain hazardous substances in electrical and electronic devices (SCP Malaysia, 2014). In Indonesia, a recommendation on industrial waste management is still being formulated by the Ministry of Industry and the United Nations Development Programme. This recommendation will aim to reduce or eliminate substances, including PBDEs, that can endanger the environment (Pusat Penelitian Kimia LIPI, 2017).

2. Phthalates

Phthalates or phthalic acid esters (PAEs),  found mostly in polyvinyl chloride (PVC), are plasticisers that can take 10%–60% concentration by weight of PVC. Since these additives are not bounded to polymer matrix,  they can easily leach into the environment during their manufacture, use, and disposal. A big concern is that phthalates can serve as endocrine disruptors even in small concentrations (Hermabessiere et al., 2017). 

3. Bisphenol A (BPA)

As one of the most commonly and globally produced chemicals, BPA is primarily used as monomer of the main component of the lining of aluminium cans. Humans are exposed to BPA  once it is released from food and drink packaging. Like phthalates, BPA is a significant endocrine disruptor. Other types of bisphenol, including bisphenol B, F, and S, may also pose threats to the environment (Hermabessiere et al., 2017).

4. Nonylphenols (NPs)

NPs are widely used as antioxidants and plasticisers in plastic production. They leach out of plastic bottles. Effluents from wastewater treatment plants are also a major source of NPs. These additives disrupt the endocrine system and can have adverse impacts on human health and the environment. NPs are banned in the EU. NPs can be found in seafood, including oysters, mussels, and fish (Hermabessiere et al., 2017).

5. Antioxidants

Antioxidants help prevent ageing of plastic and delay oxidation but can leach out of plastic packaging and into food. The use of antioxidants in plastic can be harmful because they are oestrogen mimics (Hermabessiere et al., 2017). One of the classes of endocrine disruptors, an oestrogen mimic is an artificial hormone that biologically behaves as oestrogen but has a different chemical structure. Excessive amounts of estrogen in the marine environment can impact marine animals by delaying their sexual maturity, decreasing the size of male reproductive anatomy, and making eggs thinner (UWEC, 2020). 

These additives can be found in marine water, sediment, and microplastic. As the final stop of all wastewater, marine water receives huge volumes of additives. PBDEs, di (2-ethylexyl) phthalate (DEHP), and NP are mostly detected in marine water. Additives can also be found in sediments affected by anthropogenic discharge through wastewater, atmospheric deposition, and sewage sludge. Plastic additives are found in microplastics since they are added in the manufacture of polyethylene and polypropylene (Hermabessiere et al., 2017).

Several studies on the chemical impacts of plastic have been conducted in Southeast Asian and East Asian countries. A study in the Mekong River Delta in Viet Nam revealed PBDE contamination in catfish, posing risks to people who eat them. This study showed that runoffs from dumping sites during floods and rains are the possible drivers that bring additives to surrounding areas. In this case, municipal wastes in dumping sites, consisting of household goods and electrical equipment, might contain PBDEs. Research in informal e-waste recycling sites in Viet Nam found high PBDE contamination in surrounding sediment and in fish, particularly mud carp. This was attributed to the high level of PBDEs in plastic parts in obsolete electronic equipment in e-waste recycling sites. Liu et al (2011) discovered PBDE contamination in tissues of marine fish from the South China Sea, the Bohai Sea, the East China Sea, and the Yellow Sea, while Ilyas et al. (2013) indicated that a high level of PBDEs was observed in municipal dumpsites. Seabirds are also vulnerable to the impacts of chemicals in plastic. A study in the northern Pacific Ocean discovered oceanic seabirds ingesting plastic debris due to the growing amount of plastic entering the ocean. PBDEs were found in the abdominal adipose tissue of the species.

References