Radiation, microwaves and cancer

This page tells you about microwave ovens and different types of radiation. There is information about

• Microwave ovens
• What radiation is and the different types
• Research into microwave ovens and cancer
• More information

Microwave ovens

Microwave ovens don’t make foods radioactive. They just heat them. Microwave ovens heat food by producing radiation which is absorbed by water molecules in the food. This makes the water molecules vibrate and produce heat, which cooks the food.

Any modern day microwave oven in good condition is perfectly safe as long as you follow the instructions for use. If you use a microwave oven in the correct way there is no known harmful effect on humans. But people still tend to worry. Understanding the different types of radiation may help to reassure you that cooking in a microwave is not dangerous and won’t cause cancer.

Although microwaves are safe to use it is important to point out that cooking in them can affect the nutritional value of some foods - for example, fruit and vegetables. But nutrients are lost when heating foods in any way - boiling, grilling, frying or even steaming. As long as you don't overcook foods, microwaving can actually be quite a healthy way to cook, as it uses only a little water. The best way to keep as many nutrients as possible in fruit and vegetables is to use as little water as you can and not overcook them.

What radiation is and the different types

Radiation is the release of energy from any source. There are many different sources of energy around us. For example, our bodies give off heat, which is a form of energy. Energy is also released from everyday things such as

• Household electrical appliances
• Heaters
• The sun
• X-ray machines

Not all radiation is harmful. It depends on the type of radiation and how much exposure to it you have. There are several types of radiation. All of which can be grouped under either

• Ionising radiation
• Non ionising radiation

Ionising radiation

Ionising radiation is what most people mean when they talk about radiation. This type of radiation is made of high energy waves. It is quite a complicated process. But the end result is the energy can get into cells and chemically change the way the cell works. This is called ionisation. As we know from medical tests, very small amounts of ionising radiation don’t do us too much harm. But too much can cause burns, radiation sickness, and cancer.

The genetic material of a cell (known as DNA) is very sensitive to ionising radiation. DNA is a code for all the genes that carry the instructions for how our body works and its characteristics. For example, there are genes to tell the body to have brown hair or blue eyes.

Ionising radiation can change a cell’s DNA. If this happens, then the cell’s in built instructions about how to live and grow are jumbled around. It is then possible for the cell to do something very different from what it is supposed to do. For example, it may become cancerous and keep reproducing in an uncontrolled way. This could take years to happen but it still means that a cancer may eventually develop.

There is more information about the cancer cell in the about cancer section.

Ionising radiation can damage any cell in the body. But it all depends on how much radiation the cell gets. There are 3 main types of ionising radiation that you may be exposed to. Too much of any of them can harm the body. They are

• Natural background radiation
• Medical radiation
• Non medical radiation

Natural background radiation

We are constantly being exposed to ionising radiation from natural sources. It comes from

• Radioactive substances in the soil
• Radioactive gases given off from the earth, such as radon
• Very small amounts of radioactivity in the body
• Cosmic rays from the solar system (the sun, stars and outer space)

Medical radiation

The use of radiation in medicine includes

• Diagnostic radiology, which includes using X-ray machines to get pictures of the inside of the body
• Nuclear medicine, which involves drinking a radioactive substance or injecting it into the body to help with diagnosing or treating diseases and
• Radiotherapy, which uses high energy rays to kill cancer cells

Non medical radiation

This includes nuclear radiation that comes from previous nuclear weapon explosions or accidents throughout the world, such as that at Chernobyl.

Non ionising radiation

Non ionising radiation has enough energy to move things around inside a cell but not enough to change cells chemically. The radiation from a microwave oven is non ionising. Other examples include

• Ultraviolet rays from the sun or sunbeds
• Electromagnetic fields
• Radio waves
• Radiation waves given off from household electrical appliances, heaters, mobile phones with or without headsets, and computers and their screens

The only type of non ionising radiation that we know can cause cancer is over exposure to ultraviolet rays, which causes skin cancer.

Research is going on into other types of non ionising radiation and any possible link to cancer. We have information about the investigation of cancer risk and electromagnetic fields, mobile phones andcomputer screens.

Research into microwave ovens and cancer

Studies have looked at the possible link between microwave ovens and cancer. Some results suggest there may be a link but other studies haven’t been able to prove this at all. Microwaves do produce a magnetic field while they are in use. This drops sharply the further you are from the oven and doesn't last long, as you tend to cook in microwaves for very short periods. Most experts say that microwave ovens don’t give off enough energy to damage the genetic material (DNA) in cells so they can’t cause cancer. Microwaves heat food, but do not make any changes to it that aren't made in any other cooking method. So they do not make food any more likely to cause cancer. 

More information

The Health Protection Agency Centre for Radiation, Chemical and Environmental Hazards is an independent body that advises the Government about health risks associated with radiation. They also have information for the public. Their website has a section about radiation.