Hard-Boiled Eggs Still in Their Shells
Think twice before tossing that leftover hard-boiled egg into the microwave for a quick warm-up. Whether in the shell or peeled, hard boiled eggs heated in the microwave release steam. The steam cannot escape the whites, so pressure builds. When you cut (or worse, bite) into the egg, the steam is released instantly. The resulting explosion may burn you. It’s basically like creating a tiny pressure cooker that’s waiting to explode. Exposure to high levels of microwaves can cause a painful burn. Two areas of the body, the eyes and the testes, are particularly vulnerable to RF heating because there is relatively little blood flow in them to carry away excess heat. Even experienced cooks get caught off guard when that innocent-looking egg suddenly erupts like a miniature volcano. The best approach is to slice the egg before reheating, or better yet, just eat it cold.
Styrofoam Takeout Containers and Coffee Cups
The U.S. Food and Drug Administration (FDA) has deemed polystyrene food containers and packaging to be safe for hot and cold food items. However, not all foam containers should be microwaved. Here’s the catch that most people miss—unless there’s a clear microwave-safe symbol on that container, you’re playing with fire. There is a chance that, when heated, some styrene can migrate into the food within the container. This is particularly true for fatty items such as meats and cheeses. This is potentially concerning as styrene has been identified as a cancer-causing agent. Additionally, foam containers that are not marked as microwave-safe could melt or catch on fire if microwaved too long. Avoid materials that can pose potential hazards, such as metal, aluminum foil, containers with metallic accents, and plastic containers not labeled as microwave-safe or made from materials like polystyrene (Styrofoam). Your morning coffee might taste fine, but the invisible chemical migration happening in that foam cup isn’t worth the convenience.
Fresh Grapes and Similar Round Fruits
Who would have thought that innocent grapes could turn into tiny plasma generators? Grapes become superheated, and the sugary pulp quickly turns into molten plasma. They could explode in the microwave, while you’re stirring, or even when you take a bite, sending ultra-hot fruit flying. Scientists have actually studied this phenomenon extensively. Similar to leafy greens, grapes can also ignite in a microwave. Due to the heat and pressure of the microwave, grapes tend to explode, as the sugar in them turns into plasma, which is then expelled around the microwave. This plasma can catch fire inside or outside the microwave which can burn you when you’re taking them out or eating them. The physics behind it is fascinating, but the cleanup and potential injuries definitely aren’t. If you want warm grapes for some reason, try roasting them in the oven instead.
Plastic Wrap That Touches Your Food
Using plastic wrap in the microwave isn’t automatically dangerous, but doing it wrong definitely is. Avoid allowing plastic wrap to come into contact with food, especially when heating or if the food has a high fat content (like meat or cheese). The real problem starts when that clingy wrap actually touches your food during heating. If food must be covered, then use paper towel, not plastic wrap. Condensation underneath the plastic wrap, which could contain phthalates, could cause fluid to drip down into the food, Halden says. Think of it like this: when plastic gets hot, it starts sweating chemicals, and you definitely don’t want that chemical sweat dripping into your dinner. Plastic wrap and plastic containers that aren’t microwave-safe can melt into your food, and we don’t want to be eating bits of plastic. Even microwave-safe wrap should be vented and kept away from direct food contact.
Metal Objects Including Aluminum Foil
This one seems obvious, but you’d be surprised how many people still try it. Metal cannot absorb these microwaves. This means that electromagnetic energy is built up on the metallic surface. This causes sparks, and in more severe cases, fires or explosions. Placing metal inside the microwave is unsafe as it reflects the microwaves, causing sparks and potentially creating a fire hazard. This means metal containers, pottery with a metallic finish, metal utensils and silverware, tin foil, and other things containing metal should never be used in the microwave. Even tiny bits of metal can cause problems—that decorative rim on your favorite mug or a forgotten fork can turn your microwave into a fireworks display. The electromagnetic waves literally bounce around like angry bees, creating arcs of electricity that can damage your appliance or worse. It’s not just about the sparks you can see; the damage to your microwave’s internal components can be permanent and expensive to fix.
Whole Fruits with Thick Skins
Whole fruits can build up steam inside their skins and explode in the microwave. Cut fruits into smaller pieces before microwaving, or avoid microwaving them entirely. Think of fruits like apples, tomatoes, or pears as nature’s pressure cookers—their skins act as perfect seals that trap steam inside. Plasma might not be produced from other fruits, but you could still be left with a mess. Whole fruit traps steam under the flesh, meaning it could burst while it’s heating. When that pressure builds up and finally releases, it’s like a food volcano erupting inside your microwave. The hot fruit pulp can splatter everywhere, creating both a mess and a burn hazard. Even worse, the explosion often happens with a delay—sometimes when you’re taking the fruit out or cutting into it. If you need warm fruit, either pierce the skin several times or cut it into pieces first.
Breast Milk in Bottles or Storage Bags
Never thaw or heat breast milk in a microwave. Microwaving can destroy nutrients in breast milk and create hot spots, which can burn a baby’s mouth. This isn’t just about convenience—it’s about your baby’s safety and nutrition. Many new mothers freeze and store their breast milk for later use, which is great, as long as it’s not reheated in a microwave. In the same way that microwaves heat plates of food unevenly, they can also warm a bottle of breast milk unevenly, creating “hot spots” that can severely burn a baby’s mouth and throat. Some studies suggest that microwaving baby formula or breast milk can degrade some important nutrients. The American Academy of Pediatrics specifically warns against this practice because those essential antibodies and nutrients that make breast milk so valuable for infant development get destroyed by microwave heating. Instead, warm the bottle in a bowl of warm water or use a bottle warmer designed for this purpose.
Processed Meats and Deli Products
Bacon, hot dogs, lunch meat, and sausages should be cooked on the stove or in the oven, not in the microwave. Heating these processed meat products leads to the formation of cholesterol oxidation products (COPs). COPs have been linked to coronary heart disease. Research suggests COPs may also be linked to inflammation, plaque buildup in the arteries, and more health conditions. The problem isn’t just about uneven heating—it’s about creating harmful compounds that weren’t there before. Processed meats often contain chemicals and preservatives that extend their shelf lives. Unfortunately, microwaving them can make those substances worse for your health. Those preservatives like nitrates and nitrites that keep your deli meat looking fresh can transform into potentially carcinogenic compounds when hit with microwave radiation. Your morning bacon might cook faster in the microwave, but your arteries will thank you for taking the extra few minutes to cook it properly on the stove or in the oven instead.
What surprised you most from this list?
