The Scenario: Your friend is what you'd call a Microwave Power User. If there's a Hot Pocket in her freezer, it's going to get nuked within the next day or two. Breakfast, lunch, or dinner, she's basking in the 700 watt glow of her 1.7-cubic-foot lover, a Jimmy Dean sausage breakfast biscuit rapidly steaming up its plastic-covered canopy. And if she has leftovers, that eggplant Parmesan will be spinning around in its warped Tupperware container.
While your friend has no problem putting her wrapped food or plastic containers in the microwave, you're worried she's on a slow march to death with every butter-coated popcorn bag. Is it safe to cook food in a microwave, even in "microwave-safe" packaging?
The Reality: Your friend's love affair with microwaving every meal of the day isn't actually harmful. Microwaving her food doesn't technically increase her risk of getting cancer, since it uses electromagnetic radiation to heat food, not radiation related to cancers or nuclear reactions.
It's apparently the plastic, not the radiation, that's the problem. Microwave radiation has virtually "no effect at all" on your health, says Hans Ringertz, adjunct professor of radiology at Stanford University. "The material you have around it may produce dangerous substances when heated. The chemicals occur because the microwave effects the heating…[it's the same effect] as if you heated whatever material you had the food in an ordinary oven," Ringertz says. "If the packaging contains poisonous, chemical substances, that would be the same if the food was heated in the microwave or any other way to prepare food."
Your friend's far from health conscious, even if she has salmon and broccoli in that plastic container once in awhile. But while the old adage that microwaves release cancer-causing chemicals called dioxins may have long been debunked, the plastic surrounding her food may contain BPAs, a harmful industry chemical used in plastics since the 1960s. This, along with phthalates, (the chemicals that make plastic flexible yet hard to break) can leach into her food. They may be safe at very low levels, but still have the potential to cause health effects on the brain, behavior, and even the prostate gland of fetuses, babies and children. Even BPA-free products can cause health problems, including increased estrogen levels.
The Worst That Can Happen: The packaging around her microwaved food, not the microwaving process itself, could lead to serious health issues and symptoms. Plastics leaching into the food, heated or even not heated, can lead to increased estrogen levels and endocrine-disrupting issues. Your friend may experience symptoms of weight gain, hair loss, feeling tired, trouble sleeping and even increased symptoms of PMS. At its worst, higher estrogen can put your friend at a higher risk for breast cancer.
Ringertz compares the chemical effects of the microwave and plastics to cigarettes, including the tobacco plant and the paper around it. "Cigarettes create the long-term risks of lung cancer because you inhale it," he says. "In the same way, substances you heat up around the food [you put in the microwave] would give the same potential risks and long-term effects inside the body."
What is Probably Happening: While she may not get breast cancer, melted plastic in her food could lead to some less dire, albeit still unpleasant, symptoms of higher estrogen levels. This might affect her energy and concentration at work or personal life. By the way, don't be fooled by all the estrogen talk—BPA has been shown to affect men negatively as well.
As for nutrition, your friend is probably still getting nutrients from her food if she's zap-steaming vegetables in a small amount of water, but not so much the salisbury steak with macaroni and cheese frozen dinner (which may come with a plastic tray, leading to the aforementioned issues).
What to Tell Your Friend: Your friend can microwave to her heart's content, but she should play it safe and refrain from doing so in plastic or other potentially hazardous materials. She should consider microwave-safe ceramic bowls and non-plastic containers (not aluminum foil, though, unless your friend wants to play firefighter in her kitchen).
Read This Next: How Bad is a Serious Caffeine Habit?