From the ‘material of 1,000 applications’ to a waste product, the history of plastic is a journey through innovation, change and growing challenges. The first products consisting partly or exclusively of artificial raw materials were developed as early as the 19th century. Plastics have been produced commercially since the beginning of the 20th century. Fuelled by the shortage of natural materials during the Second World War, the demand for plastic alternatives increased rapidly. Because they were cheap to produce and versatile, they soon replaced products made of wood, metal, cotton, ivory or glass.

These figures can be explained by the use of plastic by the economy and society: producing new plastic from fossil components is cheaper than collecting, cleaning, reprocessing and reusing reusable products. The chemicals used in plastic production, such as flame retardants, plasticisers, fillers and dyes, make the recycling process even more difficult. 

In most cases, only items made from a single type of polymer can be effectively recycled. The additives they contain play a crucial role in determining the quality of the recycled material. But the sheer variety of these substances often results in what’s known as “downcycling” – where recycled products are of lower quality and limited use compared to the original.

The wide range of chemical additives comes with another serious drawback: of the more than 16,000 different substances used in plastics, over 4,000 are known or suspected to be harmful, and for the vast majority, their effects remain unknown.⁽⁵⁾ In addition, unintended reactions during the manufacturing process can produce unknown compounds, known as non-intentionally added substances (NIAS). 

This chemical complexity poses a major challenge to creating a successful circular economy for plastics. The consequences are tangible. The diversity in chemical composition directly affects recycling and has a clear impact on the environment. Around 11 per cent of plastic waste ends up polluting waterways across the globe.⁽⁶⁾ 

Plastic makes up a large proportion of marine litter, with around three quarters of waste consisting of plastic. Unlike many other substances, plastic does not break down naturally. Its durability is seen as a benefit during use - but once discarded, that same quality becomes a curse. Plastic doesn't simply go away. Not even in the ocean.

Common sources of plastic waste are:

• Illegal or unmanaged rubbish dumps
• Tyre wear from road traffic, which contributes microplastics
• Wastewater treatment plants, which often fail to fully filter out microplastics from household sources such as cosmetics and synthetic clothing
• Shipping and maritime transport. For example, through lost cargo from freighters and container ships, the erosion of paint on ship hulls (a source of microplastics), or illegal dumping of waste at sea
• Fishing, due to lost or deliberately discarded nets and lines
• Agriculture, where plastic sheeting is used to cover fields
• The plastics industry through the loss of plastic pellets even before they are processed into plastic products. 

Only rough estimates can be made of how much plastic waste is added each year. This is because the routes and time spans by which plastics are transported from the hinterland to the coast, and ultimately into the ocean, are too varied. In dynamic coastal environments characterised by tides or seasonal weather phenomena, the amount of plastic in the marine environment can fluctuate greatly over short periods. Additionally, some coastal plastic waste is transported back and forth by tides and changing wind directions. This makes it difficult to estimate exact quantities. The proportion of plastic waste that is deliberately or accidentally disposed of in the sea can also only be estimated.

No matter where humans look in the world’s oceans: plastic is already there. Every marine environment studied so far has been found to contain plastic waste. Much of it floats on the surface, but many fragments sink into deeper waters and eventually settle on the seafloor.

Plastic has even been discovered in the Mariana Trench, the deepest known point in the ocean, nearly 11,000 metres below the surface. And it hasn’t stopped there: plastic pollution has reached remote coastal areas and even the distant, uninhabited marine regions of the Arctic and Antarctic.

Basically, plastic is designed not to break down. Its durability is intentional and useful during its period of use - even if, in the case of packaging, that period is very short. However, this strength becomes a curse afterwards, because plastic does not rot. At the same time, it doesn’t keep its original shape. Over time, plastic becomes smaller and smaller. This isn’t due to the material breaking down chemically, but rather to its breaking apart or more accurately: fragmenting. This means that larger plastic items such as bags, fishing nets or packaging gradually break down into ever smaller pieces through exposure to UV rays, friction and the salt in seawater.

At some point, these particles become so small that they measure less than a millimetre and are classified as microplastics. But the process doesn’t stop there: even then, the particles continue to get smaller and more numerous, because they do not disappear, they persist. As fragmentation continues in the ocean, a single plastic fragment measuring one centimetre could theoretically break down into a quadrillion (1,000,000,000,000,000) tiny particles at the nanometre scale.

As the size of the plastic particles shrink, their chances of interacting with marine life increase. This is because ever more tiny fragments accumulate within marine ecosystems. As a result, a larger number of organisms come into contact with and ingest these particles, either because they adhere to algae or are present in the water, or because they are already in smaller marine organisms that are consumed by larger ones. Microplastics can be consumed by far more species than larger plastic debris, ranging from tiny zooplankton to massive whale sharks. Many of these creatures form the foundation of the food web, which means plastic can potentially travel up through different levels of the food chain and end up on our plates.

The first reports of marine fish encountering plastic waste date back nearly 100 years. As early as the 1920s, researchers observed mackerel and other fish with rubber bands embedded in their bodies.⁽¹⁾ Since then, scientists have continuously gathered evidence of marine life coming into contact with plastic debris.

• Entanglement – Marine animals often get caught in discarded fishing nets, balloon strings, or long plastic bags. The plastic wraps around their bodies, trapping them or causing injuries. If fish or invertebrates remain entangled for too long, they may starve or become easy prey. Marine mammals can suffocate because they cannot reach the surface quickly enough to breathe.
• Covering: Plastic bags or tarpaulins can lie on the seabed, for example, or cover plants and animals. The longer a piece of plastic covers an area, the less oxygen there is under or in the plastic, which can lead to the death of organisms or plants.

• Other interactions – This category includes, for example, birds or other animals using plastic pieces to build their nests. It also covers cases where animals get trapped inside plastic containers and cannot escape, or where bottom-dwelling creatures bury plastic fragments deeper into the seabed. Additionally, this includes the breakdown of plastic into smaller pieces caused by marine animals.

The impact of plastic on a living organism depends on many different factors. The type of interaction largely determines the possible effects on the organism. In addition, the size relationship between the organism and the plastic piece, as well as its shape and flexibility, play an important role. The duration of the interaction and the amount of plastic involved are also significant.

Possible effects on the organism are influenced by the type and properties of the plastic’s chemical components, additives such as plasticisers, pollutants, and the biological communities that develop on the plastic over time in the ocean, also known as the ‘plastisphere’. The plastisphere can host microorganisms, animals and plants that may serve as food for other organisms but can also have harmful effects. Factors such as the developmental stage, sex, health condition and overall resilience of a marine creature also shape the potential consequences of interacting with plastic debris.

The effects of plastics and the chemicals they contain on individual organisms can vary greatly. In laboratory and field studies, researchers have demonstrated a range of effects, from minor or temporary health impairments to serious injuries, blockages of the digestive system, reduced growth, developmental and reproductive disorders, physiological changes, inflammatory reactions, organ damage and even death. However, some studies have not been able to prove any negative consequences of interaction with plastic for living organisms, and others have shown that organisms have adapted to increased exposure at a given site.

These varying results can partly be explained by the factors already mentioned (see infographic) and the wide range of possible effects from interactions. Additionally, plastics and their additives impact multiple levels of biological organisation, ranging from individual molecules to entire ecosystems. This complexity makes it harder to detect and compare results across different studies. On top of that, marine ecosystems are under pressure from many other stressors, such as changes in temperature and pH, the release of pharmaceutical substances, and more. As a result, the overall combination of factors is highly relevant and calls into question analyses that focus only on individual factors.

The consequences of plastic pollution for animals, plants and marine biodiversity, as well as marine ecosystems and the diversity of effects, must therefore continue to be researched intensively. Only by basing our understanding on reliable findings from German and international marine research can we assess and address the ecological and economic consequences of plastic pollution through political initiatives, technical innovations and international legislation.

Plastic pollution in the oceans not only has mostly negative ecological consequences—it also leads to economic losses. Direct costs arise when potential damage needs to be prevented or actual damage repaired. Examples include beach clean-ups in tourist areas and the removal of ghost nets blocking ship propellers.

Indirect costs arise from losses in production or income, for example when fishermen catch less fish or fish of lower quality due to marine pollution, leading to a drop in market prices. So-called ‘welfare costs’ are also part of these indirect costs. These include damages caused by plastic waste to human health or the loss of ecosystem services.

Calculating the precise amount of indirect costs caused by reduced ecosystem services due to plastic pollution is a major challenge. It is estimated that every tonne of plastic in the oceans causes a loss of profits of between 3,300 and 33,000 US dollars.⁽¹⁾ Extrapolating this figure to the total amount of plastic waste in the oceans would result in an annual loss of between 500 and 2,500 billion US dollars due to reduced marine ecosystem services.

According to the Food and Agriculture Organization, more than 3.3 billion people worldwide obtain at least one-fifth of their basic animal protein needs from consuming fish.⁽²⁾ In poorer countries such as Bangladesh, Cambodia, or Gambia, the reliance on fish as a protein source is typically even greater. Fish is not only an essential and affordable part of many diets but also an important source of income: up to 820 million people worldwide depend directly or indirectly on fisheries and aquaculture.⁽³⁾

Nonetheless, smaller plastics - along with the chemicals and environmental pollutants they carry - can enter the edible parts of fish and seafood, and ultimately the human body. The resulting health risk is also the subject of current research.⁽⁵⁾ Although studies on the extent and effects of microplastic exposure in humans are still in their early stages, tiny plastic particles have already been detected inside the human body. Researchers have found plastic fragments in the digestive tract, blood and blood vessels, lungs, heart, placenta, and even in breast milk. Laboratory tests with human cell lines suggest inflammatory reactions, for example in inflammatory bowel disease, blood cells and brain cells, with reactions including cell death.⁽⁶⁾ Recent findings also indicate a possible link between nanoplastic particles and Parkinson's disease or dementia.⁽⁷⁾ 

Plastic pollution is a global and rapidly growing problem that urgently needs to be addressed. This is well understood by politicians and has been recognised at the highest levels of international cooperation - a crucial step given the global scale of the issue. For example, the United Nations has embedded the goal of maintaining clean ecosystems on land and in the sea within several of its Sustainable Development Goals (SDGs):

Problem identified, problem solved? Not quite. But progress is underway. Currently, 175 member states of the United Nations are working together on a global plastics treaty. At the European Union level, there are also promising initiatives, particularly in the areas of recycling and reuse.

In March 2022, the United Nations Environment Assembly met in Nairobi, Kenya, to address the growing global plastic crisis. At the summit, 175 countries voted in favour of drafting a legally binding agreement to combat plastic pollution. A timeline was agreed with the aim of implementing the treaty by the mid-2020s.

The agreement will bind countries to strict standards for plastic consumption, providing a clear path to a future without plastic pollution. The idea is that a common standard will create a level playing field for all and provide the necessary incentives and support for national measures.

To contain and prevent further discharges of plastic into the world's oceans, all stages of the plastic life cycle and the stakeholders involved must be addressed, from the extraction of raw materials to production, use and disposal.

An often cited positive example of such a global environmental agreement is the Montreal Protocol for the protection of the ozone layer. Since its introduction in 1987, more than 99 per cent of ozone-depleting substances have been phased out through uniform global bans and the ozone layer has been put on a gradual path to recovery.

There is also movement at the European level. Following the 2019 Single-Use Plastics Directive, which banned the sale of certain disposable plastic products such as cutlery and drinking straws, the focus has now shifted to improving plastic recycling – with the aim of keeping plastics out of the environment. But recycling is far from straightforward.

Since the beginning of industrial plastic production, the vast majority of plastics have been made from non-renewable raw materials. According to figures from the plastics industry association Plastics Europe (2022), over 90 per cent of all plastic products manufactured in 2021 were derived from fossil resources such as crude oil. That leaves the global share of plastics from circular or bio-based production chains at less than ten per cent.

There are several reasons why recycled plastic – known as recyclate – still accounts for such a small share of production:⁽²⁾

• the wide variety of plastic compositions makes recycling more difficult
• the quality of plastic degrades with each recycling cycle
• recycled material is often more expensive than virgin plastic
• fresh (virgin) plastic must often be added to maintain performance standards
• the level of contamination in recycled plastics is rising

As part of the European Green Deal, the Circular Economy Action Plan has been renewed, outlining key conditions and possible solutions to tackle plastic pollution more effectively.⁽³⁾ Among the priorities identified are the following:

• a robust legal framework for sustainable product policy
• focus on key value chains across sectors and industries – including electronics, ICT, batteries and vehicles, packaging, plastics, textiles, construction, food, water and nutrients
• technological advancement of existing recycling plants, waste collection systems and sorting infrastructure
• deposit-return schemes for high-quality plastics and a general shift from single-use to reusable products
• innovative product design – for example, the development of alternatives to plastic fishing gear such as Dolly Ropes (see info box)
• “design for recycling” principles, with incentives to use high-quality, single-grade plastics that can be more easily reused

There is no quick fix; the solution must lie in addressing the problem at its root. This means reducing plastic use, especially single-use plastics and packaging, and maximising the recycling of existing plastics. Achieving this will require cooperation from the international community, not only at the governmental level but also across scientific, economic, and civil society sectors.

While the production of plastics has significantly advanced the fisheries and aquaculture sector, it has also become a major contributor to marine pollution. It is estimated that between 17 and 22 per cent of plastic debris found on the seabed or suspended in the water column can be traced back to fishing and aquaculture activities.⁽⁴⁾ This sector is thus a significant source of marine plastic waste, yet it is also directly affected by the adverse ecological and economic impacts of both micro- and macroplastic pollution. Consequently, there are initiatives aimed at reducing plastic waste in this area through innovation.

One notable example is the so-called Dolly Ropes. These are fishing lines composed of numerous individual orange or blue plastic fibres, which are attached to bottom trawl nets as a form of chafing gear. However, they begin to fray after just a few days of use and frequently end up in the environment. Dolly Ropes are particularly common on the seabed and beaches of the North Sea, for instance.

To address this problem, experts from the fishing industry collaborated with researchers from the Thünen Institute of Baltic Sea Fisheries. Their solution was the development of a buoyancy device that eliminates the need for Dolly Ropes altogether. Many German crab fishers have already adopted this cost-effective and more sustainable alternative.

Es gibt auch Ideen, den Müll aus dem Meer abzusammeln. Schwimmende Reinigungsgeräte (sogenannte Clean-Up-Geräte) können in begrenztem Ausmaß Kunststoffteile an der Wasseroberfläche einsammeln, allerdings handelt es sich dabei nur um die sprichwörtliche Spitze des Eisberges. Der an der Oberfläche treibende Kunststoffmüll ist nur ein Bruchteil der im Meer befindlichen Menge. Der weitaus größere Teil des Kunststoffmülls verbreitet sich in den darunter liegenden Wassermassen oder lagert sich am Meeresboden ab und kann nicht in großen Mengen geborgen werden. Zudem fangen die meisten Sammel-Technologien ungewollt Meeresorganismen mit ein, was ihren ökologischen Nutzen infrage stellt. Viele Wissenschaftler und Wissenschaftlerinnen fordern daher global geltende Kriterien zur Prüfung der Umweltverträglichkeit und Wirksamkeit solcher Technologien. Ferner sollen die Geräte nur zur Renaturierung von äußerst stark belasteten Lebensräumen zum Einsatz kommen und dürfen nicht zu Greenwashing führen. Das heißt: keine Plastik Offset Programme.