Plastic pollution, where does it come from? After the discovery of various plastics in the first half of the 20th century, mass production really lifted off in the 1960s. From just 15 million tons in 1964 to 311 million tons in 2014. The western world developed its system of mass consumerism because of the low production price and many positive aspects of various plastics (waterproof, non-conductive to electricity, highly durable). This allowed the general public to obtain things like cars and televisions at affordable prices. But it also led to the economic profitability of single use items such as cutlery, food and drink containers, and plastic bags which in turn led to a vast increase in our general waste production.

You might expect human activity on and near the oceans to be the main source of plastic pollution. However, it is estimated that over 80% of plastics in the oceans come from land based-sources through wind and waterways. You might think that that discarded bag in your inland city will be cleaned up by someone later on, but it may well be that it is blown into a stream or river before then and transported downstream to the sea. The choices we make in cleaning up after ourselves are key, even if we live hundreds of miles from the coast.

Precisely the properties which make plastics great in their day to day use make them very persistent when they enter the environment. Their weather resistance and durability mean that they do not break down completely for vast periods of time(possibly up to hundreds of years). The vast majority of the plastics that we have released into the seas and have not retrieved in some way is still there. As marine plastic pollution is increasing dramatically, we are adding more and more to this amount every day.

Although plastics cannot break down completely (known as mineralization) due to their durable nature, a combination of UV radiation, wave activity, and animal consumption does fragment them to ever smaller particles. These particles dubbed micro-plastics (smaller than 5 millimeter) or even nano-plastics (smaller than 1 micrometer) form an omnipresent plastic soup in the oceans which may well affect marine life in unforeseen ways.

As plastics flow around the oceans, they are mistaken for food items by many marine animals ranging from tiny krill to the largest whales. It was recently found that this is in part due to the algae growing on the plastics which release a sulphurous smell as they break down. Since these algae form the basis of all life in the oceans, animals have learned to link this smell to food as it attracts small shrimps like krill which attract small fish , which attract larger fish etc. Currently more than 200 animal species have been documented as consuming plastic pollution with for example many turtle and seabird species as dramatic examples. It is of course important to remember that there is a research bias towards species that are interesting to us. There is a severe lack of data on the multitude of fish species as well as the vast array of invertebrates which form the majority of marine life. The consumption of plastics can lead to a blockage of the digestive system leading to starvation as has been found in many seabirds, but it may also lead to the leaching of toxic chemicals from the plastics into the animals since plastic particles take up vast amounts of other chemicals which can then be released as the animal attempts to digest the plastic particles.

Due to their chemical properties, plastics can easily bind other chemicals to them. Together with plastics, we have released a multitude of chemicals into the seas ranging for example from pesticides to heavy metals to flame retardants. As these toxins bind themselves to plastic particles, their concentration increases strongly compared to that in the general ocean. As the plastic particles are eaten by marine life, these toxins enter the ocean’s food webs including the fish we like to eat. These chemicals may well have detrimental effects on basic biological processes regulated through genes and hormones.

Although there are currently initiatives underway to develop technologies for the removal of plastics from the ocean surface, we should not expect a complete solution in the foreseeable future. The sheer enormity of the world’s oceans and the amount of plastics in them will make even partial removal a monumental task and designs large enough to potentially make a significant impact which are currently proposed face feasibility criticisms. We should of course continue to develop techniques on which we can build in the future, but the projects currently under development should not be seen as a miracle cure. One major issue with projects aimed at scooping plastic from the ocean surface is that they will be scooping many types of marine life with it, for example algae and zooplankton. These small forms of life form the basis of all life in the open ocean and any technique should make sure they are not significantly impacted. Next to that, there are estimates that the majority of plastics in the oceans are not present at the open ocean surface, but are eaten by animals, or sink down to deeper levels due to growth of plants and animals on them, or just because they are types of plastics with less buoyancy. Next to the development of new technologies for removing the plastics from the oceans it is key that we act first and foremost on the continued release of our plastic waste into the oceans. Reducing the gigantic amount of plastics being released into the oceans every year begins with each of us at home, or outdoors thinking about how we are using and disposing of plastics.

Even if we would have technologies available which would allow us to remove the plastic pollution from the oceans, the cost will be enormous due to the sheer size of both the oceans and the amount and nature of plastics already present. However, we can reduce these future costs by acting now in reducing plastic pollution in our day to day lives. Developing a circular economy and reducing our everyday use of especially single use plastics will take some effort, but the costs to society will be a fraction of what will be needed to clean our oceans when we remain on our current trajectory. Many changes you can make in your own life do not even need to cost anything, or will earn themselves back as your investment in re-usables allows you to stop buying single use containers.