Microwave ovens have been the norm for almost 50 years, but ever since they were first introduced, microwaves have been a source of controversy. While manufacturers and retailers maintain that microwaves are completely safe, many people still aren’t convinced.
Many of the original concerns about microwave safety, such as radiation leaks and pacemaker malfunctions, have been addressed by modern technology. However, there remain real, potentially serious, health issues that arise from microwave use. Leaks, burns, nutritional concerns are all good reasons why you may want to consider a different cooking method.
How Microwaves Work
Since microwaves were first available, the biggest concern people have had is the danger of keeping a household appliance designed specifically to create radiation. Microwaves cook food using microwave radiation, generated by a device called a magnetron. Microwave radiation is non-ionizing which means it’s relatively low energy. That may sound good, but low radiation is different from no radiation. The effects of long-term, low-dose, non-ionizing radiation are difficult to observe, and we don’t yet know the full consequences for the human body. Many Doctors in the Functional Medicine field, such as Dr. Mercola and Dr. Axe, recommend against their usage for this reason.
Something else we must consider is that even at peak efficiency, domestic microwaves do leak some heat. The US Food and Drug Administration allows for some leakage as long as radiation levels fall below what they consider harmful to humans.
A 2004 study found that small doses of ionizing radiation over the course of years may increase the risk of leukemia. However, this doesn’t tell us much about microwaves. That study focused on the effects of ionizing radiation — specifically the type found in medical scanners. Because microwaves produce non-ionizing, electromagnetic radiation, the study isn’t applicable. As of this writing, no long-term studies on the effects of microwave radiation on humans have been completed.
How Microwaves Affect Food Quality
Microwaves do alter the nutritional content of food; this fact is not in debate. The real question is if microwaving food alters its nutritional content differently than other forms of cooking. All cooking changes the chemical structure of food to some degree, but different types of heating alter the nutritional content in different ways. For example, broccoli loses about 74 to 97 percent of its antioxidants when boiled, but retains its nutrients when steamed.
So what nutrients are specifically affected by microwaving? Alliinase, found in garlic, is one. Alliinase is an enzyme with significant benefits for the immune and cardiovascular systems. Unfortunately, it’s sensitive to heat. Forty-five minutes in an oven will render alliinase inert. That’s bad, but there’s a lot you can cook in under 45 minutes. In a microwave, it takes just 60 seconds.
Do you have a breastfeeding infant? Never warm breastmilk in a microwave. Microwaving destroys the essential disease-fighting, baby-protecting agents in breast milk. In one study, breast milk microwaved for just 30 seconds destroyed natural antibodies, paving the way for the growth of potentially harmful bacteria. 
There are more examples of compromised nutrition. An Australian study showed that microwaves cause a higher degree of “protein unfolding” than conventional heating. If you have a choice, you want your proteins properly folded. Protein nutrition depends on its structure — when it unfolds, it becomes just a strand of amino acids. You lose the nutritional functionality of the protein. Microwaves are also capable of extensively fragmenting and destroying bacterial DNA, doing so to a far greater degree than heating alone.
Microwaving Food in Plastic
Another danger of microwaves comes from the type of cookware you use. If you heat food in a plastic container, some of the chemicals that make up the plastic can leak into your food. Toxic chemicals, like acetyltributylcitrate and dioctyladipate, are common components of plastic food containers. Whenever you heat plastic containers, utensils, or wrap, they release a small portion of these chemicals into your food.
The rate of chemical absorption depends on a number of factors. Temperature, duration of heat, plastic type, and food composition all affect chemical transfer. Old, scratched, or damaged containers are more likely to release harmful particles. Regular use, including cleaning, increases the rate at which the plastic degrades. Heating increases the rate of chemical transfer by 55x. While all methods of heating increase the leach rate, microwaves seem to cause a higher transfer rate than other methods.
Microwaving plastics that aren’t rated microwave-safe is an especially bad idea. Containers made out of polyethylene terephthalate (PET or PETE, or plastic #1), such as most soda bottles, can leach carcinogenic, hormone-disrupting phthalates after repeated use. Commercial-grade cling wrap (commonly found in delis) is made from polyvinyl chloride (PVC, or plastic #3). PVC can release cancer-causing dioxins. Polystyrene (PS, or plastic #6, Styrofoam) is another troublemaker. The base component, styrene, has been associated with skin, eye, and respiratory irritation, depression, fatigue, compromised kidney function, and central nervous system damage.
OK, so you’ll only use products labeled as microwave-safe. That should be fine, right? Unfortunately, no. “Microwave safe” is not a particularly strict term. For example, #7 polycarbonate is a durable plastic found in some Tupperware containers and baby bottles. It’s usually labeled as “microwave safe.” The National Institute Of Environmental Health Sciences, however, warns that microwaving causes polycarbonate plastic to break down. Polycarbonate releases hormone-disrupting bisphenol A (BPA), especially when heated.
The Milwaukee Journal Sentinel did an analysis on “microwave safe” products. The study found that products marketed for infants release toxic doses of bisphenol A when heated. In a lab, the containers were heated in a microwave or conventional oven. All of them released toxic amounts of BPA — enough to cause neurological damage in lab animals.
In another study, The Washington Post put hundreds of plastic products through “real world” scenarios, including microwave warming. Results showed that hormone-disrupting chemicals seeped from 95% of the products. Worse, that only accounts for the chemicals we already know are dangerous. As lead scientist Deborah Kurrasch, pointed out, “A lot of the alternative chemicals have not been adequately tested because they don’t have to be… A compound is considered safe (by the FDA) until proven otherwise.”
The truth is that there are better options. Even if you’re too busy to spend all day over a hot stove, there are simple, delicious, nutritious meals that can be prepared in about 10 minutes.
If you do still choose to use a microwave, follow the below guidance to help protect your health;
Read and follow the manufacturer’s instructions.
Do not stand directly in front of a microwave while in use.
Do not microwave plastic, especially plastic bags or wrap.
Make sure that the door seals are clean and free of debris.
Have all repairs done by a qualified service person only.
Never use any microwave if the seals are damaged or if the door is damaged in any way, especially if the door won’t close tightly or if the oven continues to operate with an open door.