The starting materials come from crude oil

1. Most polymers are made from alkenes such as ethene and propene.
2. Those alkenes come from cracking the heavier fractions of crude oil.
3. Crude oil is finite, so the supply of starting material is limited.
4. Demand for polymers competes with demand for fuels from the same oil.
5. As oil becomes scarcer, the cost of making polymers rises.

Polymers persist in landfill

1. Most polymers are not biodegradable, so microorganisms cannot break them down.
2. A polymer buried in landfill therefore persists for a very long time.
3. Landfill sites fill up, and new sites take up land.
4. Polymers that reach rivers and the sea remain there, harming wildlife.
5. The unreactivity that makes a polymer useful is what makes it persist.

Burning polymers releases harmful gases

1. Burning a polymer releases carbon dioxide, which is a greenhouse gas.
2. Incomplete combustion releases carbon monoxide, which is toxic.
3. Burning PVC releases hydrogen chloride, which is acidic and corrosive.
4. Those gases must be removed from the exhaust before it reaches the air.
5. Burning does at least release energy that can be used, and it takes up no land.

Recycling requires sorting

1. Different polymers must be melted separately to be reused.
2. A mixture of polymers gives a material of poor quality.
3. Sorting is therefore needed before anything can be reformed.
4. Sorting by hand is slow and costly, and automatic sorting needs expensive equipment.
5. Items are often labelled with a code to make sorting possible.

Weighing the case for recycling

1. Recycling saves crude oil, since less new polymer has to be made.
2. It uses less energy than making the polymer from oil.
3. It reduces landfill and the litter that escapes from it.
4. Against that, collecting and sorting cost money and energy of their own.
5. A recycled polymer is often of lower quality, so it cannot always replace new material.