Should You Microwave Food in Plastic? What the research Says

What people claim

You will see two opposite claims online. One says microwaving any plastic leaches dangerous chemicals into your food. The other says that if a tub carries a microwave symbol, there is nothing to worry about. Both go further than the evidence.

What the evidence shows

The 2023 Nebraska study

Researchers at the University of Nebraska-Lincoln tested polypropylene tubs and a polyethylene food pouch filled with water or a mild acid (to mimic acidic foods like tomato sauce). Microwaving released the most particles of any use they tested. Some containers released up to 4.22 million microplastic and 2.11 billion nanoplastic particles from one square centimetre of plastic in three minutes. Storing food in the fridge or at room temperature for six months also released particles, but less.

They then modelled exposure and estimated the highest daily intake at about 20 to 22 nanograms per kilogram of body weight for infants and toddlers eating microwaved food from polypropylene. In a lab dish, very high doses of the extracted particles killed many human kidney cells. That cell test used doses far above what anyone would eat, so it does not show harm at real-world levels. Other scientists have written in the same journal questioning parts of the method, which is normal for new research.

What UK regulators say

In the UK, plastics meant to touch food fall under retained Regulation 10/2011, which sets limits on how much of certain substances can move from plastic into food. Makers must state the conditions their product is tested for, such as time and temperature, as Trading Standards' guidance explains. That is why a microwave symbol matters: it means the product was meant to be heated.

These rules were written mainly around chemical migration, not micro and nanoplastic particles. The Committee on Toxicity, which advises the Food Standards Agency, has said there is little data on how swallowed microplastics affect mammals, no human studies, and that a full risk assessment is not yet possible. So UK regulators have not said microwaving labelled plastic is harmful, and they have not said particle release is harmless either.

Who might reasonably switch to glass

• Anyone who reheats food in plastic most days, such as packed lunches at work.
• Parents of babies and toddlers, who eat more per kilogram of body weight. The NHS already says never to warm baby formula in a microwave, because it heats unevenly and can scald.
• People with old, scratched, cloudy or warped plastic tubs, which are worth replacing anyway.

Who should be careful

• Do not microwave takeaway tubs, margarine tubs or other packaging not marked for microwave use.
• Do not let cling film touch food in the microwave.
• Glass and ceramic get very hot; use oven gloves and let food stand, as microwaves heat unevenly.
• Never microwave a glass container with a metal-trimmed or clip lid on; take plastic lids off and cover with a plate instead.

If you want to switch: what to look for

• Borosilicate or tempered glass that the maker says can go in the microwave and oven.
• Glass lids if you want no plastic near hot food, or plan to take plastic lids off before heating.
• Sizes that suit you: one portion for lunches, larger for batch cooking.

Our picks below are glass containers we already recommend in our food storage guides.

Our picks at a glance

How we chose

We reused glass containers already verified for our food storage guides, chose ones that can go in the microwave, and favoured glass lids. We checked UK prices in October 2026.

Pyrex Zero Plastic Rectangular Storage Box

French-made borosilicate glass base and glass lid, so nothing plastic is near hot food. Reheat with the silicone seal removed. Caveat: heavier than plastic, and the glass lid can chip at the edges.

Pyrex Zero Plastic Set of 3

Three stackable glass dishes with glass lids, ideal for batch cooking and reheating. Caveat: Pyrex sells several Zero Plastic sets, so check capacities before buying.

Tatay Cook and Eat Glass Storage Set of 3

Three glass bases that go in the oven to 240°C, for under £13. Caveat: the lids are plastic, so lift them off before microwaving and cover with a plate instead.

Simple rules for reheating food

• Move it to glass or ceramic before reheating, especially fatty or acidic food such as curries, sauces and soups.
• Cover with a plate, not cling film, to stop splatters.
• Keep plastic for cold jobs: storing salad, cheese or dry goods in the fridge or cupboard involves no heat.
• Retire tired tubs: replace plastic that is scratched, cloudy, stained or warped, as worn surfaces are more likely to shed.
• Do not reheat in single-use packaging unless the label says it is designed for the microwave, as ready meal trays are.
• Stir and stand: microwaves heat unevenly, so stir halfway and let food stand before eating, especially for children.

None of this needs expensive kit. A couple of glass dishes and a dinner plate as a lid will cover most reheating.

Bottom line

Microwaving labelled plastic is legal and meets UK chemical migration rules. But lab work shows heat makes plastic shed many more tiny particles, and nobody yet knows what those do in the body. Switching to glass for reheating is cheap and easy, so it is a sensible precaution, not an emergency. Keep using plastic for cold storage if you like, and replace any tubs that are scratched, cloudy or warped.