After reading a recently published journal article (Koushal et al. 2014), I realised we haven’t actually explained the plastic issue on our blog in great detail. I guess we were assuming everyone has a similar knowledge and understanding about marine litter.
With reference to Koushal et al. (2014) I am going to give a quick overview of plastics and why they are an environmental issue.
If you want to read the paper yourself you can find it in the International Journal of Waste Resources. An online Open Access and peer-reviewed journal: plastics: issues, challenges and remediation.
Fantastic plastic? Plastics have become a fundamental part of our day to day lives. They are inexpensive, durable, convenient and have multiple uses. Having a look at the desk in front of me, my computer, mouse, keyboard, phone, stapler, scissors, pens and ruler are all made of plastic. We use plastic every day to carry out simple tasks. Food items are more often than not packages in plastic. This functionality provided by plastic has made our lives simpler. They have replaced metals, glass, paper and cardboard, offering benefits over these alternative materials. Cost is reduced because plastics can be mass produced. They are robust and can probably last hundreds of years. Our use of plastics is expected to continue to rise to meet consumer demands.
So what’s wrong with plastic? Over the years research and technological advancement has led to new, safer forms of plastics, but this comes at a cost, both to human health and the environment. Plastics are non-biodegradable, they build up in the environment adding to the ever growing rubbish piles and land-fills. As plastics do not break down naturally, they will remain in the environment as waste for a very long time. As more plastics are made to replace old and discarded plastic, there is a never ending cycle of plastic production and disposal.
But we recycle plastic: Yes, this is a convenient and easy way to reduce the amount of plastics that end up in land fill. This requires smart sorting, and efficient ways to separate the different types of plastic. The picture below lists the different types of plastic that can be recycled. Often if you look on the bottom of plastic products, you can see the triangle with a number indication the main constituent polymer in the plastic.
What about biodegradable plastics? These are very similar to conventional plastics, however they have the natural ability to decompose, breaking into natural and safe byproducts. Bio-plastics, which are naturally derived plastics, come from biological sources including cellulose. They degrade in open air, or compost using fungi, bacteria and enzymes.
What are the impact of plastic on the environment? As there is no “safe” way to dispose of plastic, there are several ways it can have an effect on the environment.
1. During plastic production chemicals additives are incorporated into the polymer matrix to give plastics their desirable qualities. These chemicals, can also be released during the manufacture process, adding another significant source of environmental pollution.
- carcinpogenic chemicals
- neurotoxic chemicals
- hormone (endocrine) disrupting chemicals
Many of these chemical additives are classed as persistent organic pollutants or POPs, which are a consider harmful under the Stockholm Convention. For example: PVC often contains vinyl chloride, dioxins, phalates and other plasticisers; Polystyrene contains benzene; formaldehyde and Bisphenol-A are found in poly-carbonates.
2. Plastic can also affect the environment during their use. An example of this is through the release of toxic gases or dust, during installation and use.
3. Plastic disposal is possibly the most problematic area, and where the environment is most at risk. Plastics’ durability and resistance to degradation is one of the reasons it poses a large environmental threat. If plastics are not recycled (even then only 10% is recycled effectively) they are sent to land fill. Synthetic polymers do not break down and as a result plastic will persist in the environment. Plastics are also sent to incinerators where toxic compounds are released into the atmosphere where they can accumulate in the ecosystem. If plastics are lucky, they might escape land-fill and find themselves in one of the many waterways leading to the sea. The density of plastics is often less than seawater, and plastics can float around on currents and accumulate in areas such as the Great Pacific Garbage Patch in the North Pacific Ocean. This is not the only area plastic accumulates, there are similar gyres in all of the worlds oceans
Over time plastics can break down into smaller and smaller pieces through the process of fragmentation and UV exposure, but the tiny pieces or microplastic will never full break down and disappear (out of sight, but not out of mind).
What are the impact of plastic on organisms? Many reports of plastic debris in the environment have focused on larger items known as macroplastics. infact most of the information we have on plastic debris comes from the marine environment. Numerous reviews have commented on the impacts and effects of their presence in the marine environment so I wont go into great detail here (e.g. Derraik 2002, Gregory 2009). Macroplastic is commonly reported due to large size and visible implications which are regularly depicted in reports such as those by the United Nations Environment Programme (UNEP 2011).Birds, sea turtles and marine mammals are among the groups of organisms known to be affected by entanglement and ingestion of macroplastic. The consequences of this interaction includes impaired movement, reduced feeding ability, decreased reproductive output, lacerations and ulcerations, and death. Below is a video that I find really interesting, photogrpaher Chris Jordan discusses his Midway Project; which documents the ingestion of plastic and subsequent death of albatross.
The Marine Strategy Framework Directive has identified understanding the ecological implications of plastics to monitor the environmental status of the marine environment. Plastic size will play a key part in the effects it will have on different marine species and as it breaks down into smaller and smaller pieces the effects are still being determined.
Plastic can contain a number of chemicals that are toxic, and have been used to give the polymers specific properties. An example of one such chemical is Bisphenol-A. It is a plasticiser which is known to have negative effects on the endocrine system of humans and animals. Toxic monomers have also been linked to caner and reproductive problems.
Plastics can also attract chemicals, such as POPs from surrounding sea water. As a result plastics could act as transport vectors of contaminants to “clean” environments, or marine organisms.
The most likely route of exposure to these chemicals is through ingestion of contaminated chemicals. Studies have been conducted to understand how chemicals could transfer from plastics to organisms, and the current level of understanding (based on models) may indicate that the chemical transfer from plastics might not be significant as first thought.
A quick note on single use plastics (and reasons why I have given them up for a 6 weeks)
Toxicity is an issue for single use plastics. Phthalates and Bisphenol-A can leach form plastics into food and water. This type of plastic, when discarded can end up in waterways where they can continue to leach chemicals into the environment. Bisphenol A used to be found in a lot of polycarbonate food grade plastics, but has a strong oestorogenic effect. To put things bluntly, it make things more feminine and has been linked to effects on pregnancy.
Koushal et al. conclude stating that it’s not the plastics to blame, but the misuse of plastics. Maybe with a little at source reduction (reduce and reuse of plastic) and by altering the design, manufacture and use of plastic we might be able to start reducing the effects plastic debris can have on the environment.
I am interested to hear your opinions on the topic. If you have an comments or want to add further to this, please feel free to leave a comment, or contact me on our email: email@example.com