ocean plastic impact

Plastic waste kills up to 1 million seabirds, 100,000 marine mammals and countless fish and other marine organisms each year. An estimated 40% of marine mammals and 44% of seabird species are currently affected by marine debris. By ingesting macroplastics such as plastic bags (which can easily be mistaken for a squid or jellyfish, a delicacy for turtles), the digestive tract and intestine can be filled, causing inflammation and eventual death. Macroplastic such as ghost gear can entangle marine life, strangling it, cutting into it or even drowning it, or sink to the ocean floor where it can destroy marine habitats like coral reefs or mangroves, limiting their natural development and limiting their capacity to support marine life.

While the tragic impact of macroplastics is clear, we are only just beginning to explore the effect of microplastics on marine life, the marine food chain and on humans.

High levels of microplastics have been measured in the air we breathe, in the soil in which we grow our crops, in the ice at both poles, in the snow which falls on the highest mountains, in clouds at altitudes of up to 3.5 km, in rain, in drinking water and in our bodies, our hearts and lungs, even in breast milk and in the placentas of unborn babies. Over time plastic breaks up into smaller and smaller particles, small enough to be swallowed by the tiniest of zooplankton and light enough to be transported by wind or water over large distances. About a third of all plastic waste ends up in either soil or freshwater, often through the use of sewage sludge as fertilizer on agricultural land. This contains high levels of microfibres from washing cycles, meaning that thousands of tonnes of microplastics are being added to the soil and taken up by crops each year.

The microplastics in the ocean are clearly being taken up by marine life which may well be attracted to them by their odour or colour. They may be swallowed or even enter via the gills. Consumption of microplastics in place of food clearly has a negative impact on the growth, feeding capability and reproduction rates of all marine life. Microplastics may just pass straight through the digestive tract and be expelled with little effect but it is more likely that they accumulate and begin to fill up and clog the digestive system. The effect of the toxic elements that are either already inherent within microplastics or have become attached to them is still unknown. Many of the microplastics already contain toxins - microfibres from clothes for example often carry chemicals such as plasticizers for increased flexibility, flame retardants and antimicrobial agents, car tyres contain numerous toxins such as benzene and mercury, and paint is high in copper and other biocides.

Exacerbating the problem is the fact that the microplastic particles act like a sponge in the water, attracting, absorbing and storing chemicals already present in the water such as pesticides, contaminants or bacteria. These endocrine disrupting chemicals pose a huge threat to marine life. When ingested these contaminants are released, altering oxygen levels in cells, reducing energy levels and causing a variety of health problems, from tissue damage, impaired reproduction or embryonic development to cancer. 

The marine food chain passes the microplastics and their chemicals on from plankton to fish to humans. Adding together all the microplastics we breathe, drink and eat, it is thought that children and adults might ingest an average 5 grammes of plastic every week, equivalent to the weight of a credit card, which, according to the WWF comes to about 100,000 pieces of microplastic every year.

One further aspect of marine plastic is the fact that floating litter can transport so-called rafters, microorganisms, algae or invertebrates, over extensive distances from one area of the ocean to another, allowing non-indigenous species to enter new areas, affecting local ecosystems in the same invasive manner as biofouling from a ship’s hull or marine life released with ballast water. While natural flotsam has always existed in the form of macroalgae, broken off wood, ice or volcanic pumice, anthropogenic flotsam in the form of marine debris far outnumbers it and therefore intensifies the problem. 

Of greater concern is the fact that plastic pollution is effecting the ocean's inherent ability to mitigate climate change. The biological carbon pump, in which phytoplankton and zooplankton capture carbon at the ocean surface and transport it down to the mesopelagic or twilight zone, enables the ocean to extract such high levels of carbon from the atmosphere - currently around 25% of the carbon emitted by humans since the industrial revolution. As ocean plastic breaks up into microplastics, plankton are attracted to it, mistaking it for food, eating it and thereby reducing their metabolic rates and levels of reproduction. As more and more plankton are impacted by plastic, so too is their ability to absorb carbon. Similarly, fish and marine life which ingest microplastics are less able to lock carbon into the deep ocean through their faecal pellets. Microplastic which makes its way through the digestive tract of marine life has a buoyant effect on the faeces produced, preventing them from sinking to the ocean floor where the carbon would normally be stored. 

Plastic production and the climate

Putting aside the impact of plastic on the environment after its useful life, the plastic production industry’s impact on our climate is also massive, accounting for about 8% of the total amount of oil consumed worldwide (4% as a feedstock and 4% as a fuel in the refining process), an amount which is expected to reach 20% by 2050. The extraction and distillation of this oil emits high levels of greenhouse gases, with production and incineration of plastic adding more than 850 million tonnes of greenhouse gases a year to our atmosphere. It is the production phase which has the most significant impact: thermal cracking and polymerization use extremely high levels of energy and emit high levels of carbon dioxide, one ethane cracker alone can emit up to 2.25 million tonnes of carbon dioxide a year. Projections for 2050 put emissions at 2.8 billion tonnes, equivalent to 15% of the carbon budget - as pressure grows on governments to move away from extracting fossil fuels and to invest in renewable energy sources, fossil fuel companies are ramping up their production of plastic, expanding or constructing new petrochemical facilities and investing in increasing production levels despite the fact that the plastic market already has more plastic than we can use. 

Once used and then discarded, we are looking at yet further emissions. Plastic that ends up in landfill or in the environment slowly degrades and releases methane in the process. The growing use of incineration in plastic waste management as a source of waste energy means that even more concentrated greenhouse gases are emitted.

It is high time that attention is brought to the impact of plastic production on the climate and in particular on the ocean. Significant steps need to be taken in order to do so, including putting a cap on the production of virgin plastic, ending the subsidies provided by governments around the world to the fossil fuel industry and stopping the development of further plastic production facilities. 

What do microplastics do to us?

The truth is that we are yet to find out. While research is ongoing into the effects of microplastics on the human body, it is known that microplastics bring a host of problems with them. The chemicals added during the manufacture of plastic products to enhance their various properties, to make them more flexible, more heat resistant, maybe just to add a colour, are released as the plastics break up into these tiny pieces. Plasticizers and phthalates, the chemical additives used to make plastics soft and flexible or durable, are oily liquid chemicals which are colourless and odourless and they do not evaporate easily. 

Microplastic particles act as magnets, attracting toxic pollutants that already exist in the soil or ocean, such as those from insecticides or pesticides. As these pollutants enter the food chain through crops or fish stocks, or are absorbed in our bodies via the lungs, the  chemicals are absorbed into cells and interact with each other, potentially leading to a range of health conditions from allergies, diabetes and obesity, to infertility and the development of cancer and heart disease. While adults are much less sensitive, the uptake of the same number of plastic particles and their chemical compounds can lead to serious health problems in foetuses or young children.

Plastic pollution has yet to be blamed for a single human death and research into the effect of microplastics on human health is still in its infancy. What has been found, however, is that about 20 tiny pieces of plastic are present in every 10 grams of stool which, when scaled up, means that around 800 microplastics pass through our digestive systems every day. As long as these simply pass through the gastrointestinal tract and are flushed out as waste this may not pose a problem (at least in terms of our health, the microplastics do of course then need to be caught by a water filtration system before they enter the ocean). 

Research published in 2022 proved that microplastics can also enter the bloodstream and from there our internal organs, where the toxic chemicals they carry with them can disrupt our hormone balance, earning them the name endocrine disruptors. These can cause an imbalance in the hormones which regulate our metabolism, growth and development, tissue function, reproduction, sleep, and mood and may be responsible for hormone-related forms of cancer such as breast and testicular cancer.