Plastics — from oil to waste

Raw material, additives, manufacturing, use, collection and real end destinations.

An extraordinary material we use as if it disappeared

From an oil molecule to an object that lasts decades

The vast majority of plastics begin their story in oil or natural gas. In a refinery or a petrochemical plant, these fossil raw materials are transformed into relatively simple base molecules, which are then chained together through a process called polymerization to form the long molecular chains that give plastic its characteristic properties. Additives, pigments and stabilizers are then added to those base chains, adjusting the final material's flexibility, color, light resistance or flammability, and a moulding process gives each object its specific shape. The result is an extraordinarily useful material: lightweight, durable, a thermal and electrical insulator, and cheap to produce in large quantities. That same usefulness has made it possible to reduce the weight of vehicles and aircraft, keep fresh food edible for much longer, and manufacture disposable medical equipment that prevents infections. The underlying problem is not that plastic is a bad material: it is that, in a huge fraction of its uses, the material's physical durability far exceeds the actual duration of the use it is put to, often minutes or hours against centuries of potential persistence.

What happens after it's thrown away, step by step

Once discarded, a plastic object can follow several different paths, and each one recovers a very different fraction of its original value. Reusing it directly, with no transformation at all, is the option that preserves the most value, because it keeps both the material and the already-manufactured shape intact. Mechanical recycling — washing, shredding into small pieces and re-melting the material — recovers the material but not the original shape, and its final quality is limited by the mixture of different plastic types, residual dirt, incorporated additives, and the progressive degradation of the molecular chains with each melting cycle. Chemical recycling tries to go further, breaking the plastic back down into simpler molecules that can be used as new raw material, but that process has its own energy cost, its own yield — never one hundred percent — and its own economic cost, which still limits its use at large scale. Incinerating plastic recovers part of the chemical energy stored in it as electricity or heat, but emits carbon dioxide and leaves ash that also requires management. Depositing it in a controlled landfill physically contains it, but occupies space indefinitely and requires ongoing control to prevent leaks into the environment. Abandoning it outside any management system disperses it and lets it fragment with no control whatsoever — the worst of all possible fates.

The words on the packaging don't always mean what they seem to

The "biodegradable" label on a package depends critically on the specific conditions under which that material breaks down — temperature, humidity, the presence of certain microorganisms — and in practice, many plastics labeled biodegradable only truly degrade in specific industrial facilities, not in a conventional landfill or in the open natural environment; that label, in no case, authorizes abandoning the object outside a waste-management system. Similarly, the "recyclable" label describes a technical possibility of the material, not a guarantee that the specific municipality where that person lives will collect it separately, nor that an industrial buyer actually exists willing to process that recycled material. A multilayer package, which combines several sheets of different materials to better protect a specific food and extend its shelf life, can perform that protective function extraordinarily well and, at the same time, turn out to be practically impossible to separate into its individual components for effective recycling — two properties of the same object competing with each other, not canceling each other out.

The hierarchy begins long before reaching the bin

The decision with the greatest real effect does not happen at the moment of throwing away the packaging, but much earlier: avoiding genuinely unnecessary plastic uses, reusing objects with a design specifically intended for that purpose, simplifying the materials used in a product to make later separation easier, correctly depositing what is discarded into the appropriate collection circuit, and truly recycling only what has a real industrial circuit capable of processing it. Replacing plastic with paper, glass or metal, without first comparing the package's total mass, the energy cost of transporting it, and the real conditions of use, can shift the environmental problem onto another material rather than solving it: a glass container, for instance, usually weighs and takes up considerably more space than its plastic equivalent, which can increase the energy cost of transporting it the same distance.

The hierarchy before the bin

  1. Avoid genuinely unnecessary plastic uses, rather than automatically replacing them with another material without comparing the real outcome.
  2. Reuse objects with a design intended for it; it preserves both the material and the already-manufactured shape.
  3. Simplify a product's materials when you can choose: a single-material package separates and recycles much better than a multilayer one.
  4. Dispose of it correctly into the right collection circuit; badly sorted plastic lowers the quality of the whole recycled batch.
  5. Recycle only what has a real circuit: "recyclable" describes a technical possibility, not a guarantee that an industrial buyer exists for that material in your municipality.

Don't swap one problem for another without comparing

Switching plastic for glass, paper or metal without comparing mass, transport and real conditions of use can shift the environmental impact onto another material rather than eliminating it. "Biodegradable" does not authorize abandoning an object outside the waste-management system: it almost always requires specific industrial conditions to truly break down.

The numbers, with their source

From 2 to 400 million tonnes a year in seventy years

Global plastic production has grown at a rate of 8.4% a year from just 2 million tonnes in 1950 to about 400 million tonnes in 2022. Without significant restrictions, the OECD projects global production could reach 1.2 billion tonnes a year by 2060, triple today's production.

Sources: EcoWatch — Global Plastic Recycling Rate 'Stagnant' at 9%; OECD — Plastic pollution is growing relentlessly.

Only about 9% of the world's discarded plastic is actually recycled

The global plastic recycling rate remains "stagnant" at around 9%, a figure that has barely changed in recent years despite total production continuing to grow. Of the rest of discarded plastic, around 40% ends up in controlled landfill and 34% is incinerated; the remaining share is lost outside any formal management system.

Source: EcoWatch / study cited on phys.org — Global plastic recycling rates 'stagnant' at under 10%.

What this table is missing

These percentages are global averages that hide enormous differences between countries and between specific plastic types: PET from beverage bottles, for instance, is recycled in many regions at a rate far above the global average, while multilayer packaging or mixed plastics are barely recycled anywhere in the world.

Sources

  • UNEP analyses the global plastics crisis and proposes solutions in Turning off the Tap.
  • The OECD documents global plastic waste production, use and management in its Global Plastics Outlook report.
  • Our World in Data and UC Santa Barbara (Bren School) compile statistics on global plastic production and recycling rates.