Conventional plastic
Low-density polyethylene (LDPE)
LDPE is the soft, flexible plastic of carrier bags, bread bags, freezer bags and most cling film. It's rarely collected at the kerbside yet, but supermarket collection points take most clean plastic film.
By PlasticFreeHome Research Team · Not yet reviewed by an editor · Updated 21 October 2026
- Also called
- LDPE 4, plastic 4, polythene, PE film
- Recycling code
- 4 (LDPE)
- Type
- Conventional plastic
- Found in
- carrier bags, bread and freezer bags, cling film, produce bags, squeezy bottles, the lining of some paper cups and cartons
- Heat
- Softens at low temperatures. Keep it away from hot food, ovens and the microwave.
- Recycling in the UK
- Most councils don't collect film yet. Clean bags and wrapping can go in supermarket front-of-store collections.
What it is
Low-density polyethylene is the soft, stretchy form of polythene. It carries the number 4 in the recycling triangle, when it's marked at all. Most of the plastic film in a UK kitchen is LDPE or a close relative: carrier bags, bread bags, freezer bags, produce bags and most household cling film.
Polyethylene also hides in places you might not expect: it's the thin waterproof lining in many paper coffee cups and in drinks cartons.
Cling film: PE or PVC?
Household cling film is often polyethylene. Some, especially catering film, is PVC, which contains plasticisers to make it cling. Neither should touch hot food. If the box doesn't say, assume it's plastic either way, and use a plate, a lid or a beeswax wrap instead. See cling film → lids.
Where it touches food
- Freezer and sandwich bags: cold contact, mostly low exposure, but a lot of single-use waste. Jars and steel tubs replace most of them: freezer bags → jars.
- Reheating in bags or under film: avoid it. A 2023 study found polyethylene food pouches, like polypropylene tubs, released large numbers of particles when heated.
- Produce bags: buying loose cuts them out completely: packaged produce → loose.
How to use it more safely
- Keep film and bags for cold, dry storage.
- Never microwave food in a bag or under cling film.
- Reuse sturdy bags many times; a bag for life only beats a thin bag if you actually reuse it. See carrier bags → tote.
Recycling
Plastic film is recyclable, but most councils don't collect it yet. Many large supermarkets have front-of-store collection points that take clean, dry bags and wrapping, including bread bags and the film from multipacks. Compostable bags must not go in.
Related guides
Sources
- Hussain et al. (2023), Environmental Science & Technology — microwaving polypropylene containers and polyethylene pouches released millions of microplastics and billions of nanoplastics per cm²
- WRAP (2022), Polymer choice and recyclability guidance — which plastics are recyclable in the UK, and why PVC and polystyrene are not
Swaps involving LDPE
Cling film → lidded containers or beeswax wraps
Cling film is single-use plastic in direct contact with food. A plate on a bowl does the same job for free.
High priority · about 400 g of plastic a year
Freezer and sandwich bags → jars and tins
Single-use bags add up fast. Jars, tins and paper handle nearly every job.
Worth doing · about 500 g of plastic a year
Plastic-wrapped fruit and veg → loose produce
Loose produce lets you buy exactly what you need, cutting both plastic and food waste.
Worth doing · about 2.0 kg of plastic a year
Plastic carrier bags → a tote you keep using
Worth doing, but lower priority than you might think: bags don't touch your food, and a new tote must be reused many times to pay off.
Lower priority · about 400 g of plastic a year