Microwave Oven Dangers: Real or Hoax?

A detailed look at the debate regarding the safety of microwave ovens which has raged for decades.

Online Claim

Microwave safety has been debated for decades. With the rise of the internet and social media, it is easier than ever for one side of the debate to promote their own slant on the issue. After seeing an image circulating which showed a list of 5 supposed dangers of operating microwave ovens, we decided it was time to take a closer look.

As shown in the graphic below, the image displays the “Top 5 Reasons Not To Use A Microwave” which include the following claims:

1. Microwaves were never thoroughly researched before adoption.
2. Microwaves destroy the nutrient value of your food.
3. Microwaves create carcinogenic compounds in certain foods.
4. Microwaves provide unnecessary daily exposure to radiation.
5. Microwaves can create severe health issues.

Two Sides

Before we get into each of the claims above, it should be noted that there are two sides to this debate. There is the anti-microwave camp, currently championed by Powerwatch and Dr. Joseph Mercola, and then there is pretty much everyone else who believes microwave ovens are safe. The list above appears to have origins in an article published by Dr. Mercola. The foundation of the anti-microwave school of thought presented by Dr. Mercoloa has its origins in claims made by William Kopp and Hans Hertel.

Though the merits of Dr. Mercola’s writings are fodder for a different article, it is safe to say his views are controversial and highly disputed. And not only in regard to microwave ovens, but also with such claims that HIV isn’t the cause of AIDS. Many of his ideas are not widely accepted or proven by the medical community.

Let’s take a look at this list of 5 reasons not to use a microwave.

Claim #1: Microwaves were never thoroughly researched before adoption.

The first microwave oven was unveiled in January 1947, 15 months after the filing of the US patent. There is little information about the testing and research that occurred prior to the introduction of microwave ovens. The FDA currently states:

Controlled, long-term studies involving large numbers of people have not been conducted to assess the impact of low level microwave energy on humans. Much research has been done with experimental animals, but it is difficult to translate the effects of microwaves on animals to possible effects on humans…The fact that many scientific questions about exposure to low-levels of microwaves are not yet answered require FDA to continue the enforcement of radiation protection requirements. Consumers should take certain common sense precautions.

It does appear that the testing phase wasn’t extensive from the filing of the patent until the first ovens were presented. The information available is sketchy. That, of course, was over 60 years ago. This means that microwave ovens have been in use for that long, and have been in wide use for 40 to 50 years.

A lack of thorough testing 60 years ago doesn’t necessarily mean there is danger present.

Claim #2: Microwaves destroy the nutrient value of your food.

This claim is actually true, but any form of cooking food will destroy some nutrients. This is not unique to microwave ovens. Consider the following:

Food scientist Barry Swanson remarked that microwaving can retain more nutrients than over forms of cooking.

Septuagenarian fitness expert Jim Morris states, “I microwave everything… because microwaving destroys less nutrients than any other way of cooking, including steaming and broiling.”

This abstract from 1995 concluded: “Several studies have shown that microwave cooking, if properly used, does not change the nutrient content of foods to a larger extent than conventional heating. In fact, suggests that there is a tendency towards greater retention of many micronutrients with microwaving, probably due to the shorter preparation time.”

The FDA writes, “Microwave cooking does not reduce the nutritional value of foods any more than conventional cooking. In fact, foods cooked in a microwave oven may keep more of their vitamins and minerals, because microwave ovens can cook more quickly and without adding water.”

Some point to a 2003 study in which broccoli was cooked in a microwave and lost 97% of its nutrients. As Dr. Andrew Weil points out, however, that study was flawed due to excessive use of water. A similar study using less water only showed an 11% loss, which is about the same as steaming.

Any amount of improper cooking – microwave or otherwise – can lead to a higher destruction of nutrients than proper cooking.

Claim #3: Microwaves create carcinogenic compounds in certain foods.

There are two claims regarding carcinogens in the anti-microwave camp. One is that microwaving food can create carcinogenic compounds, and the other claim is that carcinogenic toxins can be transferred when cooking food in plastic or paper wrappers.

Regarding the claim that microwaving food can create carcinogenic compounds, the Mercola camp cites Powerwatch here. Powerwatch summarizes Russian studies regarding this issue:

Carcinogens were formed in virtually all foods tested. No test food was subjected to more microwaving than necessary to accomplish the purpose, i.e., cooking, thawing, or heating to insure sanitary ingestion.

Microwaving prepared meats sufficiently to insure sanitary ingestion caused formation of d-Nitrosodienthanolamines, a well-known carcinogen. Microwaving milk and cereal grains converted some of their amino acids into carcinogens. Thawing frozen fruits converted their glucoside and galactoside containing fractions into carcinogenic substances. Extremely short exposure of raw, cooked or frozen vegetables converted their plant alkaloids into carcinogens. Carcinogenic free radicals were formed in microwaved plants, especially root vegetables.

Many experts believe that the amount of carcinogens generated is typically less from microwave use than baking or frying due to the elimination of tars and char which are created at higher temperatures.

A Cornell University study found that microwave bacon contained “significantly lower levels of carcinogenic nitrosamines than bacon that was cooked the usual way.”

A 1994 science study showed that microwaving meats and draining off the juices prior to grilling actually removed potential carcinogens by 95%:

Microwave pretreatment for 0, 1, 1.5, 2 or 3 min before frying at either 200 degrees C or 250 degrees C for 6 min per side reduced heterocyclic aromatic amine precursors (creatine, creatinine, amino acids, glucose), water, and fat up to 30%, in the patties and resulted in a decrease in mutagenic activity up to 95%.

Now let’s take a look at the second part of this argument, regarding the release of carcinogens by using plastic containers or plastic wrap:

Mercola writes, “Another problem with microwave ovens is that carcinogenic toxins can leach out of your plastic and paper containers/covers, and into your food…Microwaving fatty foods in plastic containers leads to the release of dioxins (known carcinogens) and other toxins into your food.”

The FDA states, “Some plastic containers should not be used in a microwave oven because they can be melted by the heat of the food inside.”

George Sadler of the National Center for Food Safety was quoted as saying, “It’s a chemical impossibility because the precursors for dioxin are not in the plastic wrap…I’ve seen another e-mail recently warning against using plastic wrap because of the phthalates it supposedly produces. Manufacturers quit using those many, many years ago.”

SC Johnson (manufacturer of Ziploc bags and other household products) also responded to this issue:

In 2002, we became aware of an email that was being widely circulated, which warned consumers about the alleged dangers of using plastics in the microwave. This email claimed that the combination of fat, high heat, and plastics releases dioxin into the food and ultimately into the cells of the body, thereby increasing the risk of producing cancerous cells. We researched these claims and it is clear that the information is misleading, and unnecessarily alarms consumers.

Ziploc® Brand products are 100% dioxin free. You also should be aware that dioxins can be formed only when chlorine is combined with extremely high temperatures, such as 1,500°F, which even the most powerful consumer microwave ovens are unable to produce.

Claim #4: Microwaves provide unnecessary daily exposure to radiation.

A 2000 Canadian study of 163 microwave ovens (60 new and 103 used) were inspected for microwave radiation leakage. All but a single 23-year old unit were found to be within safe limits.

According to the FDA, there have been no confirmed cases of injury from microwave radiation exposure. Further, regarding standard limits, they write:

A Federal standard limits the amount of microwaves that can leak from an oven throughout its lifetime to 5 milliwatts (mW) of microwave radiation per square centimeter at approximately 2 inches from the oven surface. This limit is far below the level known to harm people. Microwave energy also decreases dramatically as you move away from the source of radiation. A measurement made 20 inches from an oven would be approximately one one-hundredth of the value measured at 2 inches.

Microwaves rapidly lose intensity as they travel short distances, and by the time they would reach someone standing nearby, they are practically non-existent.

It is generally suggested that microwave ovens should be inspected regularly for faulty doors hinges, latches, or seals.

The Mercola camp tends to cite the opinion of a group called Powerwatch, rather than specific studies that have tested human exposure to radiation from microwave ovens.

Claim #5: Microwaves can create severe health issues.

This broad claim overlaps with the radiation and carcinogenic arguments above. Many adhering to these claims point to the findings of researcher Hans Hertel, who reported that consuming microwaved milk and vegetables could begin a process that leads to a cancerous condition. His study was never published or peer reviewed, and little is known about the specifics of his experiments. His studies have also not been duplicated.

Cancer Research UK states the following about microwaves and health:

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.

Certain Dangers

The FDA claims that the most common health hazard of microwave ovens includes burns from hot food, splattering grease, or being burned by steam. Dr. Weil also points out that the greatest dangers with microwaves are from uneven cooking, exploding/splattering food, and the use of plastic containers and plastic wrap transferring plastic molecules into food.

Bottom Line

It is best to consider the sources of each camp in this debate. The anti-microwave camp tends to rely on the Powerwatch summary of old Russian studies and reports by Kopp and Hertel that have not been peer-reviewed in legitimate scientific journals. Those claiming that microwaves are safe are backed by multiple federal agencies, university studies, and safety experts.

Although it appears that both sides of this issue can cite studies as proof that they are right, a vast majority of scholars, researchers, federal agencies, and those in the medical field have deemed microwave ovens to be safe.

Updated July 23, 2016
Originally published March 2013