Are Microwaves Safe? How Food Is Affected, Plus Safety Tips

February 10, 2020

Most of us have microwave ovens in our homes and use them several times a week. They’re convenient and allow us to reheat leftovers within minutes. But many people wonder: Are microwaves safe?

Like the recently popular air fryer, the microwave oven is valued by many because of its ease of use. It does make sense, however, that people are skeptical about its safety, considering the oven uses electromagnetic radiation to heat foods.

So what’s the deal with microwave ovens and should you avoid them altogether? Read on to find out what the studies show about microwaves.

How Do Microwaves Work?

Microwaves are high frequency radio waves that are part of the electromagnetic spectrum. The waves are absorbed by materials containing water, like your food, and the energy is converted into heat.

You can’t see it, but when you microwave food, the waves cause the molecules to vibrate and this energy creates heat.

Beyond home use for cooking and heating foods, microwaves are also used for TV broadcasting, telecommunications (including cell phones) and as radar for navigational tools. Although a microwave uses electromagnetic radiation, it’s a non-ionizing radiation, unlike X-rays.

Are Microwaves Safe?

A common concern is whether or not there are harmful effects of microwaves. Can the electromagnetic radiation produced by a microwave oven cause damage to your body or food?

Are There Microwave Health Risks?

The World Health Organization describes microwaves as “safe and convenient for heating and cooking a variety of foods” when used according to manufacturers’ instructions.

Microwaves are deemed safe because the radio waves are contained within the oven. For a microwave to work, the door needs to be shut, which limits wave exposure significantly. However, a damaged, malfunctioning or dirty microwave could allow the waves to leak.

What happens when you’re exposed to microwave energy? Think about what happens to a bowl of food. Similarly, the microwave energy can be absorbed by the body and produce heat in exposed tissues, according to the WHO. This can lead to heat damage, especially if the microwave energy is absorbed by areas that are more vulnerable to higher temperatures, such as the eyes.

A study published in Military Medical Research indicates that “electromagnetic radiation can be absorbed by organisms, in which it causes a series of physiological and functional changes.”

Studies show that microwave radiation can cause adverse reactions in the central nervous system, such as learning impairments, poor memory and sleep disorders. However, these microwave side effects occur after being exposed to a much higher frequency than what occurs in an at-home microwave oven.

For instance, industrial exposure to microwaves at a television transmitter station caused symptoms like headaches, fatigue and sleeplessness. But these people were exposed to much higher frequencies than you’d experience by standing next to a closed microwave oven.

A study published in the Journal of Radiological Protection found that although some surveyed microwave ovens leaked electromagnetic radiation, user exposure is much less than the general public exposure limit that’s set by international standards, and so they should not have a detrimental effect on a person’s health.

Based on the evidence, it appears that for thermal damage to occur from using a microwave oven, you’d have to be exposed to very high power levels for a long period of time. In general, these levels aren’t measured around standard microwave ovens.

Are Microwaves Safe for Food?

Any time you cook food at high temperatures, you are losing some of the nutrients. Microwaves, however, are generally heating foods quickly and at lower temperatures, so the idea, in theory, is that it may be retaining nutrients compared to boiling, frying or baking foods.

But there’s mixed evidence on this theory. Here’s a breakdown of what researchers have found over the years:

A 2003 study published in the Journal of the Science of Food and Agriculture evaluated phenolic compound content in broccoli after it was heated with high-pressure boiling, low-pressure boiling, steaming and microwaving. Clear disadvantages were found when broccoli was microwaved, as 97 percent of flavonoids were lost. On the other hand, steaming broccoli had minimal effects on its phenolic compounds.
A 2002 study conducted in Poland shows that both conventional and microwave heating did not reduce omega-3 fatty acid content in filets of herring.
A 2013 study published in PLos One suggests that when heating milk and orange juice, using a microwave was equivalent to conventional heating methods in most regards. However, researchers did find that the color of microwaved milk differed from control and conventional samples. This questions whether or not microwaving can alter a food’s properties in other ways.
A 2015 study published in the Journal of Food Science highlights that unlike X rays, microwaves are not able to create free radicals or disrupt molecular bonds in biological materials. Researchers point out that the only effects on foods are the results of thermal energy that’s converted from microwave energy. So the heat created from energy may alter the food’s compounds, but it’s not, according to this research, the microwaves themselves.

Clearly, there’s some mixed results from studies evaluating the effects of microwave ovens on foods, but it appears that for the most part, foods are not losing nutrients from microwaves. This is likely because microwave ovens heat foods quickly and the foods aren’t exposed to very high temperatures, unlike boiling or frying foods.

Safety Tips

Although using a microwave oven is generally considered safe, for your health and your food, there are some safety tips that may reduce your exposure to microwave radiation and changes in food compounds.

1. Make sure your microwave is in good, fully-functioning condition

Modern microwave ovens have a few elements that are meant to keep electromagnetic radiation from leaking. This includes door seals, a safety interlock device, metal shields and metal screens.

The point is to keep the waves inside the oven, but you need to ensure that these safety elements are working properly. If the microwave door doesn’t shut and lock correctly, for instance, do not use it.

2. Stand at least one foot away from the microwave

Research indicates that there’s a fast decay of radiated power density with distance. Because radiation decreases with distance, it’s best not to stand right next to the microwave or put your face up against the window.

3. Don’t microwave plastic containers

It’s best to avoid microwaving plastic because the compounds in these containers can leak into your food when heated. The two major culprits in plastic are phthalates and bisphenol A (BPA), which are known endocrine disruptors.

For a plastic container to be considered “microwave-safe,” it should not contain these chemicals. To be safe, heat foods in “microwave-safe” glass or ceramic dishware instead of plastic.

4. Be careful when heating liquids

When you are heating liquids in a microwave, be very careful handling the bowl or cup to prevent being burned. Because bubbles generally don’t escape from liquids heated in the microwave, they may boil suddenly when moved or even explode out of the cup unexpectedly, so be cautious.

Final Thoughts

Microwave ovens use electromagnetic waves to stimulate molecules in food, allowing them to vibrate and build heat.
Studies show that normal exposure to functioning microwave ovens is not dangerous to your health and will not negatively alter the compounds in food, for the most part.
It’s best to heat foods in the microwave in microwave-safe glass or ceramic dishware, stand at least one foot away from the microwave while it’s on and be careful of very hot microwaved liquids.