Sign up to access the complete lesson and track your progress!
Unlock This CoursePlastic is everywhere. It wraps your food, holds your drinks, makes up your phone case and lines the inside of your trainers. Since the 1950s, humans have produced over 9 billion tonnes of plastic. The problem? Most of it never truly disappears. It breaks into smaller and smaller pieces, polluting oceans, soils, rivers and even the air we breathe. Plastic pollution is now one of the most serious environmental problems on the planet.
Key Definitions:
These plastics are designed to break down naturally. They are made from plant-based materials like corn starch, sugarcane or potato starch. Bacteria and fungi can digest them over weeks or months. Examples include PLA (polylactic acid) used in some coffee cups and food packaging. However, many biodegradable plastics only break down properly in industrial composting conditions not in your garden or the ocean!
These are the most common plastics and the biggest problem. Made from petrochemicals (oil and gas), they can last hundreds to thousands of years in the environment. Examples include PET (drinks bottles), HDPE (milk jugs), PVC (pipes and packaging) and polystyrene (foam cups). They don't disappear they just break into smaller and smaller pieces called microplastics.
Not all plastics are the same. Scientists use a numbering system (1–7) to identify different types. Some are easier to recycle than others and some are far more dangerous to the environment. Here's what you need to know:
Used in drinks bottles and food trays. Takes around 450 years to decompose. Widely recycled but huge amounts still end up in landfill and oceans.
Used in milk bottles, shampoo bottles and plastic bags. Takes hundreds of years to break down. One of the more recyclable plastics.
Used in foam cups, takeaway boxes and packaging. Takes over 500 years to decompose. Breaks into tiny beads easily, which wildlife often mistakes for food.
Single-use plastics items designed to be used once and thrown away are the fastest-growing source of plastic pollution. Think plastic straws, cutlery, bags and coffee cup lids. The UK used around 2.5 billion disposable coffee cups per year before restrictions were introduced.
A plastic bottle thrown into the ocean today will still be there in the year 2475. A plastic fishing line could last until 3024. Meanwhile, a banana skin biodegrades in just 2–5 weeks. The difference is enormous.
Plastic waste travels through rivers to the sea
Plastic doesn't stay where it's dropped. Wind, rain and rivers carry it into the ocean. Ocean currents then move it thousands of kilometres from where it started. This is why plastic pollution is truly a global problem plastic dropped in a city in Asia can end up on a beach in Scotland.
Plastic enters the environment through several routes:
The Great Pacific Garbage Patch is the world's largest accumulation of ocean plastic. It sits between Hawaii and California and covers an area roughly twice the size of Texas (about 1.6 million km²). It contains an estimated 80,000 tonnes of plastic, with 94% of it being microplastics. Ocean currents (called gyres) trap floating plastic in this zone. It's not a solid island of rubbish it's more like a thick plastic soup. Marine animals, seabirds and fish in this area regularly ingest plastic, often with fatal results.
Plastic pollution causes serious harm to animals, plants and entire ecosystems. The damage happens in several ways:
Sea turtles mistake plastic bags for jellyfish and eat them, causing blockages and death. Seabirds like albatrosses feed plastic to their chicks, who then starve with full stomachs. Whales have been found dead with hundreds of plastic items in their stomachs. Dolphins and seals get tangled in plastic netting and drown.
Microplastics are eaten by tiny zooplankton at the bottom of the food chain. These are eaten by small fish, which are eaten by larger fish, which are eaten by humans. This process is called bioaccumulation. Toxic chemicals attached to microplastics build up in concentration as they move up the food chain a process called biomagnification.
Microplastics have now been found in human blood, lungs, placentas and even breast milk. Scientists are still studying the full health effects, but early research suggests links to hormone disruption, inflammation and potentially cancer. The chemicals used to make plastics flexible or fire-resistant like BPA (bisphenol A) and phthalates are known to interfere with the human hormonal system.
Indonesia is the world's second largest contributor to ocean plastic pollution, after China. With over 17,000 islands and a rapidly growing population, waste management infrastructure has struggled to keep up. Rivers like the Citarum River in Java became so polluted with plastic and industrial waste that the water turned black and fish populations collapsed. The Indonesian government launched a major clean-up programme in 2018, deploying the military to help clear the river. However, without tackling the root causes poor waste collection and cheap single-use plastics the problem keeps returning.
Biodegradable plastics sound like the perfect solution plastic that disappears! But the reality is more complicated. There are two main types:
The key problem is that even genuinely biodegradable plastics require the right conditions to break down. If they end up in landfill (where there's little oxygen) or in the ocean (where it's cold), they can persist for decades.
In your iGCSE exam, make sure you can explain the difference between biodegradable and non-biodegradable plastics, give examples of each and discuss why biodegradable plastics are not a complete solution to plastic pollution. Examiners love it when you show you understand the limitations of solutions, not just the benefits!
Solving plastic pollution requires action at every level from individuals to governments to international agreements. Here are the main strategies:
The most effective strategy. Say no to single-use plastics. Buy less. Use reusable bags, bottles and containers. Reducing plastic use at the source means less pollution overall.
Use items multiple times before disposing of them. Refillable water bottles, reusable coffee cups and cloth shopping bags all help reduce plastic waste significantly.
Recycling keeps plastic out of landfill and the environment. However, only about 9% of all plastic ever produced has been recycled. Many plastics are too contaminated or too complex to recycle economically.
Rwanda became one of the first countries in the world to implement a total ban on plastic bags in 2008. The ban is strictly enforced tourists arriving at Kigali airport have plastic bags confiscated. The result? Rwanda is now considered one of the cleanest countries in Africa, with visibly cleaner streets, rivers and ecosystems. The ban shows that strong government action can make a real difference, though it works best when combined with affordable alternatives for people to use.