Microwave Ovens—What’s Safe, What’s Not

Here’s a nice holiday gift—one less thing to worry about.  The December, 2010 issue of the Tufts University Health & Nutrition Letter assures readers that, if used properly, microwave ovens present no health risks.  The newsletter points out that the FDA tests microwave ovens to be sure that they meet safety standards and do not present any radiation hazard.  “The FDA has never received any reports of radiation injury as a direct result of microwave exposure,” says the Tufts publication, “and there is little cause for concern about radiation leakage unless the door latch, hinges or seals are damaged.”

BUT there can be microwave injuries if these ovens are misused. The Tufts article warns against mistakes that involve heating food either too little (not enough to kill pathogens) or too much (to cause “superheating.”)  The FDA has received reports of injuries due to superheating, which occurs when water is heated above the boiling point, and it then erupts when moved or stirred.   This risk is greatest with plain water in a clean cup, so add the teabag, instant coffee, or hot cocoa BEFORE you warm your beverage in the microwave.

Also, says Medical News Today, DO NOT MICROWAVE A BOILED EGG WITH THE SHELL INTACT.  It can explode, especially when moved, and cause a serious injury, such as the eye injury, (a corneal perforation) sustained by one child.  Even a shelled whole egg may spatter and mess up the microwave.  If you must reheat an egg in the microwave, cut it up before doing so. Also, pierce hot dogs and potatoes to keep them from exploding. 

In addition, microwave users may risk accidents or consumption of harmful chemicals by placing the wrong containers or covers in the microwave. Don’t use metals or aluminum foil (with a few exceptions) and avoid most plastics. If you’re not sure whether a particular piece of pottery or dinnerware is microwave safe, here’s a good tip from Clemson Cooperative Extension:  “…place the empty utensil in the microwave alongside a cup of water in a glass measure.  Microwave on high for one minute. If the dish remains cool, it is safe to microwave.  If the dish gets warm or hot to the touch, do not use.”  

These are safe to use in a microwave oven:

wax paper, oven cooking bags, parchment paper, microwave-safe plastic wrap.

These are not safe to use in a microwave oven:

margarine tubs, cheese containers, and Styrofoam carry-out containers, all of which can warp or melt and possibly cause harmful chemicals to get into your food. 

Here are some additional tips on microwaving foods safety from our sources:

√ Arrange food to be microwaved evenly in a covered dish with a little liquid added.

√ Cook food to an appropriate temperature—at least 145°F for fish and medium-rare meat and 165°F for poultry.

√ Allow standing time; then, use a food thermometer to check the internal temperature of the item you’re cooking. Be sure the temperature is high enough to kill any pathogens. (To receive a link to this site’s safe cooking temperature chart, register your email in the home page “subscribe” area near Ethel’s photo.)

√ Leftovers should be reheated to 165°F.

√ Microwaves heat unevenly, so stir, rotate, or turn over food to cook evenly and safely.

√  Protect yourself from steam by using potholders to remove food from the microwave and by    keeping your face away from hot food when you’re uncovering it.

√ Do not reuse plastic trays that come in microwavable dinners.  These are designed for one-time microwaving only.

Regarding pacemakers and other electronics, the FDA says the following: “At one time, there was concern that leakage from microwave ovens could interfere with certain cardiac pacemakers.  Similar concerns were raised about pacemaker interference from electric shavers, auto ignition systems, and other electronic products.  This problem has been largely resolved because pacemakers are now designed to be shielded against such electrical interference. However, patients with pacemakers may wish to consult their physicians if they have such concerns.” 

If you’re still concerned about the effects of radiation leakage on your health or your family’s, consider this: a federal standard limits the amount of microwaves that an oven can leak in its lifetime to 5 milliwatts per square centimeter at about 2 inches from the oven surface.  This level is far below the amount that any evidence indicates could harm people.  Moreover, microwave energy decreases dramatically as the user moves away from the unit. Therefore, one simple way to decrease exposure to microwaves is to avoid standing next to the oven when it’s heating food.

For more information on microwave safety and operation, click on the Clemson and FDA sources below.

Source(s):

Tufts University Health and Nutrition Letter, December, 2010, vol.28, number 10, “Ask Tufts Experts,” p.7.

Clemson Cooperative Extension “Microwave Food Safety”
http://www.clemson.edu/extension/hgic/food/food_safety/handling/hgic3586.html

MedicalNewsToday.com  “Microwave ovens should warn of exploding eggs; girl has serious eye injury”
http://www.medicalnewstoday.com/articles/7836.php

fda.gov “Microwave Oven Radiation”
http://www.fda.gov/Radiation-EmittingProducts/ResourcesforYouRadiationEmittingProducts/Consumers/ucm142616.htm