Plain white paper towels and plates are generally safe for short microwave sessions, but many other paper products can catch fire, release toxic fumes, or leach chemicals into your food. What happens depends entirely on the type of paper, what’s printed or coated on it, and how long it stays in the microwave.
How Microwaves Heat Paper
Microwaves work by exciting water molecules. Dry paper on its own absorbs very little microwave energy, which is why a plain paper towel sitting in an empty microwave barely warms up. But paper always contains some residual moisture, and any food on or near it adds much more. As the moisture heats and evaporates, the paper dries out and becomes increasingly vulnerable to scorching. The hotter and drier the paper gets, the closer it creeps toward ignition temperature.
Research on cellulose (the main component of paper) shows that once moisture evaporates, surface temperatures can climb past 200°C. At that point, the paper’s structure becomes more porous, allowing oxygen to penetrate more easily and accelerating the conditions for ignition. This is why a paper towel that’s fine for 30 seconds of reheating can become a fire hazard at five or ten minutes.
Which Paper Products Are Dangerous
Brown Paper Bags
Brown paper bags are one of the riskiest items you can put in a microwave. They’re made from recycled materials that can contain tiny metal fragments and adhesives that aren’t microwave-safe. Those metal particles cause arcing, the sparking you sometimes see inside a microwave, which can ignite the bag. The USDA has specifically warned against microwaving brown paper bags, including the ones from grocery stores and fast-food restaurants.
Newspaper and Printed Paper
Newspaper is a serious concern because of what’s in the ink. Printing inks contain heavy metals like lead, cadmium, mercury, and chromium, along with organic solvents and compounds called polyaromatic hydrocarbons. When heated, these chemicals migrate readily into food, especially greasy or oily food. One well-studied compound in newspaper ink, benzo(a)pyrene, is a known carcinogen. Heating newspaper amplifies this migration significantly compared to room-temperature contact. The same logic applies to magazines, junk mail, or any paper with colored printing.
Recycled Paper Towels
Paper towels made from recycled paper can contain metal particles or nylon filaments embedded during the recycling process. Both can spark and ignite in a microwave. Printed paper towels carry similar risks because of the dyes used in their patterns. GE Appliances and Whirlpool both recommend avoiding recycled and printed paper towels in the microwave entirely.
Paper That’s Generally Safe
Plain white paper towels are the safest option for covering food to prevent splattering. Use them in short intervals, ideally a minute at a time, and give the towel a few seconds to cool between rounds. Don’t set a long timer and walk away. If you’re unsure about a specific brand, check the packaging for a microwave-safe label.
White paper plates without any coating or printed design are also fine for brief reheating. Parchment paper, which is coated in a thin layer of silicone, is heat-resistant and works well for microwave use. Wax paper, coated in paraffin wax, can handle brief microwave sessions like covering a bowl during reheating, but shouldn’t be used for prolonged cooking at high temperatures since the wax isn’t heat-stable the way silicone is.
Chemical Leaching Into Food
Fire isn’t the only risk. Many paper food containers and wrappers are treated with per- and polyfluoroalkyl substances (PFAS), sometimes called “forever chemicals,” to resist grease and moisture. Paper and board packaging accounts for roughly 72.5% of all studied cases of PFAS in food contact materials. These chemicals migrate from the paper into food, and heat accelerates the process.
Migration studies have found that total PFAS exposure from food packaging can exceed the tolerable weekly intake established by European food safety authorities. Some printing inks used on paper packaging also contain PFAS-related compounds that transfer into food. This is particularly relevant for takeout containers, microwave popcorn bags, and fast-food wrappers, all of which combine paper, grease-resistant coatings, and heat.
What a Microwave Fire Looks Like
Paper fires in microwaves don’t always start with visible flames. You might first notice smoke, a burning smell, or browning and charring at the edges or folds of the paper where heat concentrates. Crumpled paper is more dangerous than flat paper because the creases create hot spots where heat builds faster. If you see sparking (arcing), stop the microwave immediately but keep the door closed. Opening the door floods the interior with oxygen, which can turn a smolder into an open flame. Wait a few seconds for sparking to stop before opening the door carefully.
Practical Guidelines
- Use plain white paper towels for covering food, and heat in one-minute intervals rather than long stretches.
- Avoid brown paper bags, newspaper, and printed paper of any kind.
- Skip recycled paper products unless they’re specifically labeled microwave-safe.
- Choose parchment paper over wax paper if you need a liner or cover for longer heating.
- Don’t microwave takeout containers with paper or cardboard packaging, especially if the food is greasy. Transfer it to a ceramic or glass dish first.
- Never leave the microwave unattended when paper is inside, even for reheating.