Properties of plastics

1. Plastics are used for packaging, bottles, bags and toys because of a set of very useful properties.
2. Unreactive: most plastics do not react with water, air, acids or the food and drink they hold.
3. Durable: plastics are strong, hard-wearing and do not rot or rust, so they last for a very long time.
4. Low density: plastics are light for their size, and many plastic items float on water.
5. Non-biodegradable: bacteria and fungi cannot break plastics down, so plastics do not decay in the environment.
   1. Plastics are non-biodegradable because their long chains of carbon atoms, held together by strong covalent bonds, cannot be digested by microorganisms.
6. Cheap: plastics are cheap to make in huge amounts, so many items, such as drinks bottles and carrier bags, are used once and thrown away.

Why disposal is a problem

1. The same properties that make plastics useful make plastic waste hard to get rid of.
2. Because plastics are unreactive and non-biodegradable, discarded plastic does not rot away, so it persists in the environment for hundreds of years.
3. Because plastics are durable, every item ever thrown away is still waste, so the total amount of plastic waste keeps building up.
4. Because plastics have a low density, light waste such as bags and wrappers is easily blown by the wind or carried by water, spreading litter far from where it was dropped.
5. Because plastics are cheap and often used only once, very large amounts of plastic waste are produced every day.
6. Most plastic waste ends up in one of three places, and each one causes its own environmental challenge.
   1. It is buried in a landfill site.
   2. It escapes as litter and accumulates in the oceans.
   3. It is burned, which can release toxic gases.

Landfill sites

1. A landfill site is a large hole in the ground where waste is tipped and then buried.
2. Plastic waste in landfill does not biodegrade, so it takes up space for hundreds of years instead of breaking down.
3. Plastic items are bulky for their mass, because of their low density, so they fill landfill sites quickly.
4. As existing sites fill up, new land has to be found for more landfill sites.
   1. This land can no longer be used for farming, housing or wildlife habitats.
   2. Digging new sites destroys the habitats of plants and animals.
5. Some of the chemicals added to plastics can slowly leak out of buried waste into the soil and groundwater.

Plastics in the oceans

1. Plastic litter that is not collected is washed into drains and rivers, or blown by the wind, and much of it ends up in the sea.
2. Because many plastics have a low density, they float and are carried long distances by ocean currents.
3. Currents sweep the floating waste together, so huge amounts accumulate in certain areas of the oceans.
4. The plastic does not biodegrade, so the amount in the oceans keeps increasing year after year.
5. Sunlight and waves break large items into smaller and smaller pieces called microplastics, but these pieces do not disappear.
6. Ocean plastic harms marine animals in several ways.
   1. Animals such as seals, turtles and seabirds become trapped or tangled in plastic nets, rings and bags, which can injure or drown them.
   2. Animals mistake plastic for food, for example turtles swallow floating bags that look like jellyfish.
   3. Swallowed plastic fills an animal's stomach but cannot be digested, so the animal may starve.
   4. Microplastics are eaten by small sea creatures and pass along food chains, including into fish that people eat.

Burning plastics

1. Burning plastic waste, called incineration, reduces the amount of solid waste that has to go to landfill.
2. The thermal energy released by burning can be used to generate electricity.
3. However, burning plastics produces toxic gases that pollute the air.
   1. Carbon monoxide forms when plastics burn in a limited supply of air, by incomplete combustion.
   2. Carbon monoxide is toxic because it combines with haemoglobin in red blood cells and stops the blood carrying oxygen.
   3. Plastics that contain chlorine, such as PVC, release hydrogen chloride, a toxic and acidic gas.
   4. Burning also releases soot (carbon particles), which damages the lungs.
4. Burning plastics also releases large amounts of carbon dioxide, a greenhouse gas that adds to climate change.