It only takes a few minutes to eat hot meals. The emergence of microwave ovens has instantly made people's lives faster and more quality. But recently, many readers wrote to the "Rumors and Truth" section, saying that their circle of friends was flooded with a manuscript titled "Please stop using microwave ovens immediately." The main point is that microwave ovens are very harmful to health and can cause cancer, so they should be stopped immediately. The content of the article is well-founded and makes them feel uneasy. For this reason, the reporter of "Life Times" verified with Yun Wuxin, a doctoral student in food engineering from the Department of Agriculture and Biology at Purdue University in the United States, to answer readers' questions.

Many people believe in rumors and stop using microwave ovens

After checking the information, the reporter found that although it has been refuted many times, every once in a while, the rumor about "microwave ovens are harmful" will pop up once, and the title is becoming more and more thrilling and eye-catching, such as: "I'm going to smash the microwave oven! The shocking secret that the manufacturer will never tell you, "I want to smash the microwave after reading this", "Stop using the microwave, it will cause cancer"... The views conveyed in these articles make people doubtful, such as "Food heated in the microwave can make cancer cells fat and strong", "The brain relies on brain magnetic waves to spread, and long-term consumption of food processed by microwaves will neutralize brain magnetic waves, causing brain degeneration and magnetic waves to short-circuit", "Minerals, vitamins and nutrients in food are greatly reduced, or changed into carcinogens and many synthetic substances that cannot be decomposed by the body", "Microwave ovens turn minerals in vegetables into free radicals that can damage the human body", etc. Although these rumors are not "technical", many people believe them, and some people even put their microwave ovens in "confinement".

Ms. Li, who lives on Qingnian Road in Chaoyang District, Beijing, told reporters that her mother-in-law heard the rumor that microwave ovens cause cancer from someone while walking in the community. That night, she panicked and told her family members, and never let them use microwave ovens again. One night, Ms. Li worked overtime until 8 o'clock before returning home. Seeing that the food left for her was cold, she planned to heat it up in the microwave. Just then, her mother-in-law came out of the house, rushed over to turn off the microwave, and blamed Ms. Li for not using the microwave. Usually, the old lady also constantly collects "black materials" about microwave ovens to brainwash her family. Ms. Li and her husband did not believe it at first, but they could not stand the mother-in-law's daily talk, and they began to doubt microwave ovens.

Microwave rumors do not stand up to scrutiny

Yun Wuxin told reporters that microwaves are an electromagnetic wave, which is essentially the same thing as the radio waves, infrared rays and visible light used in radios, but with different frequencies. Microwaves are equivalent to a rotating electric field, which rotates more than 2 billion times per second. It will rotate with polar molecules such as water molecules (molecules with positive charge on one end and negative charge on the other end), so they will naturally "heat up all over the body" and the temperature will rise sharply in a short time. When the microwave oven is turned off, the rotating electric field disappears and the molecules become quiet. In this process, the water molecules themselves are not changed by microwaves. Food contains water and other polar molecules, which naturally become hot during high-speed rotation. This is the principle of microwave heating. Non-polar molecules such as air and certain containers will not be heated. You feel that the container holding the food is also hot, not because of the microwave, but because it is "scalded" by the high-temperature food. After explaining the heating principle of the microwave oven, Yun Wuxin crushed the rumors one by one.

Rumor 1: Microwave heating food will produce carcinogens. Yun Wuxin said that the essence of microwaves is electromagnetic waves. Like radio waves, infrared rays, and visible light, they will not cause cancer. On the contrary, infrared rays are also a clinical treatment method. In addition to not causing cancer to humans, microwaves will not cause food to produce carcinogens, and even help avoid the production of carcinogens. For example, fish and meat products, grilling, frying, etc. can easily cause the meat to burn, thereby producing carcinogens. In 2004, there was a relevant scientific report showing that heating with a microwave oven can effectively reduce the production of such carcinogens.

Rumor 2: Microwave ovens will cause plastic containers to release carcinogens. Some plastics do release some harmful components when heated. The U.S. Food and Drug Administration (FDA) requires that the amount of harmful substances that may be released into food during normal microwave heating in plastic containers must be less than 1% or even 1% of the harmful dose determined by animal experiments before they can be labeled as "microwave-safe". Therefore, qualified "microwave-safe" plastic containers are safe.

Rumor 3: Microwave heating will destroy all nutrients. Yun Wuxin said: "Any food processing process will change the food and may destroy some heat-sensitive nutrients. The changes caused by microwave heating are not greater than conventional heating." In April 2013, the China Household Electrical Appliance Research Institute and the National Food Quality Supervision and Inspection Center held a research results release conference on "The Impact of Microwave Cooking on Food Safety and Nutrition". The report mentioned that microwave cooking time is shorter and can retain more vitamins and minerals in food. This proves to a certain extent that the statement that "microwave cooking will lose nutrients" is not true.

Rumor 4: Microwaves will damage brain tissue. "It's pure conjecture. Microwave heating heats food, not the brain." Yun Wuxin pointed out bluntly. Putting aside the obviously unscientific statements in this rumor, such as "neutralizing brain magnetic waves" and "causing magnetic waves to short-circuit", as far as whether microwaves can leak, a large number of studies have pointed out that the microwave power leaked by a good microwave oven is far from the intensity of harming the human body. The United States stipulates that the power per square centimeter at a distance of about 5 cm from the microwave oven shall not exceed 5 milliwatts; China's standard is 1 milliwatt, which is more stringent. Therefore, as long as it is a qualified product and is not damaged during use, it will not leak microwaves that can harm the human body. Moreover, whether microwaves harm the human body depends on the strength of the energy. This is the same as sunlight: warm sunshine makes people feel comfortable, and scorching sun exposure may cause serious skin burns.

How to use a microwave oven correctly

Yun Wuxin said that for the elderly and children, it is safer to use a microwave oven to heat food and rice than gas. There are also some safety issues in the process of using a microwave oven. The US FDA has received many "accidents" caused by improper use of microwave ovens, of which two points are most worthy of our attention.

The first is overheating of liquids. When you boil water in an electric kettle or on a stove, the water "boils" when it reaches the boiling point. However, when heated in a microwave, the water does not flow, but only rises in temperature, and it may not "boil" even when it exceeds the boiling point. However, the water temperature at this time is very high, and it will boil violently with just a little disturbance. The cleaner the container and the water, the more likely such an accident is to occur. Milk, soup, porridge, etc. are also prone to "violent boiling" and rushing out of the container when heated for a long time, so you must master the time. The second is the explosion of eggs. The reason is similar to the "violent boiling" of water. The inside of the egg is overheated and under great pressure. When it is disturbed by external factors, the pressure is released and it may "explode". Therefore, when heating such food in a microwave oven, it should not be heated for too long.

(This article was written by our special correspondent Wang Ning)

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