Recently a TV survey was held on "Good Morning America" regarding microwave ovens and their usage: When asked what was most important in deciding "what to do for dinner" such as price, taste, nutrition, or convenience, an overwhelming 70% said convenience. The survey did not say but I suspect to most people that means popped in the microwave or a trip through a fast food place.
Now surely popping something in the microwave at home couldn't hurt you even if there was no nutrition left in it, right? Wouldn't they warn us or ban microwave ovens if eating food cooked in them was a major health threat? Well, the data may shock you but here are the facts...
Microwaves were discovered & their use was by made by the Nazis. They were used in their mobile support calling them the "radiomissor". These ovens were to be used for the invasion of Russia. By using electronic equipment for preparation of meals on a mass scale, the logistical problem of cooking fuels would have been eliminated, as well as the convenience of producing edible products in a greatly reduced time-factor.
Post World War-2, the Allies discovered medical research done by the Germans on microwave ovens. It was these documents, along with a n umber of working microwave ovens, that were transferred to the United States War Department. These promptly classified for reference as well as "further scientific investigation". Our ex-allies, the Russians, also retrieved some microwave ovens and conducted a thorough course of research into their biological effects. As a result, their use was outlawed in the Soviet Union at first. This lasted only about 2 years. The Soviets issued an international warning on the health hazards, both biological as well as environmental, of microwave ovens and similar frequency electronic devices.
After the war, Dr. Percy Spencer, a self-taught engineer with the Raytheon Corporation, claimed to have "invented" the microwave oven in 1946. The Raytheon Corporation did actually file the first U.S. patent on one. The first ones were called Radar Ranges in 1954. Thank You Raytheon, but I like your missiles much better!
The following is a summary of the Russian investigations published by the Atlantis Rising Educational Center in Portland, Oregon.
1. Carcinogens were formed in virtually all foods tested. No test food was subjected to more microwaving than necessary to accomplish the purpose, i.e., cooking, thawing, or heating to ensure sanitary ingestion.
2. Microwaving prepared meats sufficiently to ensure sanitary ingestion caused formation of d-Nitrosodiethanolamines, a well-known carcinogen.
3. Microwaving milk and cereal grains converted some of their amino acids into carcinogens.
4. Thawing frozen fruits converted their glucoside & galactoside containing fractions into carcinogenic substances.
5. Extremely short exposure of raw, cooked or frozen vegetables converted their plant alkaloids into carcinogens.
6. Carcinogenic free radicals were formed in microwaved plants, especially root vegetables.
What you were not told in this report is that it has since been discovered that this was a propaganda ploy by the Soviets to scare Americans. It did scare some but the vast majority of us keep on "nuking" their food...!
How Microwave Ovens Work:
Any form of cooking damages & changes the cells of the food being cooked. This means that microwave cooking is nothing unusual. Our own digestive systems destroy the cells of the food we ingest. Cellular damage in cooking is inconsequential. Any & all rumors about the unhealthiness of food cooked in microwave ovens are simply myths promulgated by people who do not understand what microwaves are & in many cases fear them irrationally. The world has been awash in microwaves from natural sources long before the developments of electricity & microwave ovens ever came into being.
Microwaves do not affect the molecular nor the atomic structure of the food, except through the thermal effects we associate with normal cooking (e.g., denaturing of proteins with heat & caramelizing of sugars). That is because, like all electromagnetic waves, microwaves are emitted & absorbed as particles called "photons." The energy in a microwave photon is so tiny that it cannot cause any chemical rearrangement in a molecule. What it can & does do is only add a tiny amount of heat to a water molecule. During the microwave cooking process, microwave photons stream into the food and heat it up. Millions of them would have to work together in order to cause non-thermal chemical changes in the food molecules and they do not do that. The photons can only work together if there is a conducting material, such as a metal wire, inside the oven. In that case, the photons can accelerate mobile electric charges along the conducting paths and create sparks. Such sparks can cause chemical damage that is identical to thechemical damage caused by scorching food with a flame or broilerEven if your microwave is full of sparks for some reason, the food will be any worse for you than it would be if you cooked it over an open flame or barbecue grill.
In a microwave oven, water-containing foods absorbs microwaves. The microwaves disappear as they pass through the food and the food becomes hotter. Microwaves are transferred from the small antenna near the magnetron to the cooking chamber by sending those microwaves through a metal pipe. This rectangular pipe is typically a few inches wide and an inch or so tall, and is called a "wave guide." Finally, the walls of the cooking chamber reflect the microwaves. When a microwave encounters a metal surface, it pushes electric charges back and forth in the metal and this moving charge causes the microwave to reflect.
Microwave ovens do not cause cancer. Microwaves are not ionizing radiation so thus they do not directly damage chemical bonds. Instead, micorwaves heat materials, most especially those containing water. As a result, they may cause damage to proteins in the same way that cooking damages proteins & hardens egg protein as an example. While such protein damage can easily cause cellular death it does not & cannot cause any type of genetic damage such as is associated with cancer.
Microwaves & Pacemakers
If a microwave oven does not leak microwaves, then it will not affect people at all. However, if microwaves do leak from a particular microwave oven, can cause undesirable currents to flow in the electric leads of the pacemaker. That is because a microwave consists of electric & magnetic fields. Electric fields exert forces on charged particles. The mobile charged particles in a pacemaker's electric wiring will experience these forces as the microwave encounters them and thus they will move back & forth with the microwave's fluctuating electric field. The pacemaker's wiring is not meant to carry these unexpected current flows so the pacemaker and/or the person attached to it may experience unpleasant effects. While such problems are very unlikely, it makes sense to warn pacemaker users whenever a microwave oven is in use.
Does microwave cooking affect the nutritional value of food? No more so than conventional heating does. Overheating some
nutrients can damage them, so that microwave cooking does affect food's nutritional value.
"PLASTIC & MICROWAVE: Carcinogens - At 10,000,000 Times FDA Limits"
Plastic and the Microwave! It's amazing what a curious student can learn. As a seventh grade student, Claire Nelson learned that diethylhexyladepate (DEHA), considered a carcinogen, is found in plastic wrap. She also learned that the FDA had never studied the effect of microwave cooking on plastic-wrapped food. Claire began to wonder: Can cancer-causing particles seep into food covered with household plastic wrap while it is being microwaved?
Three years later, with encouragement from her high school science teacher, Claire had an idea for studying the effect of microwave radiation on plastic-wrapped food, but she did not have the equipment. Eventually, Jon Wilkes at the National Center for Toxicological Research in Jefferson, Arkansas, agreed to help her. The research center, which is affiliated with the FDA, let her use its facilities to perform her experiments, which involved microwaving plastic wrap in virgin olive oil.
Claire tested four different plastic wraps and found not just the carcinogens but also xenoestrogen was migrating into the oil.
Xenoestrogens are linked to low sperm counts in men and to breast cancer in women.
Throughout her junior and senior years, Claire made a couple of trips each week to the research center, which was 25 miles from her home, to work on her experiment. An article in Options reported her analysis found that DEHA was migrating into the oil at between 200 parts and 500 parts per million. The FDA standard is 0.05 parts per billion. Her summarized results have been published in science journals.
Claire Nelson received the American Chemical Society's top science prize for students during her junior year and fourth place at the International Science and Engineering Fair (Fort Worth, Texas) as a senior.
On Channel 2 (Huntsville, AL) this morning they had a Dr. Edward Fujimoto from Castle Hospital on the program. He is the manager of the Wellness Program at the hospital. He was talking about dioxins and how bad they are for us. He said that we should not be heating our food in the Microwave using plastic containers. This applies to foods that contain fat. He said that the combination of fat, high heat and plastics releases; dioxins into the food and ultimately into the cells of the body. Dioxins are carcinogens and highly toxic to the cells of our bodies. Instead, he recommends using glass, Corning Ware, or cerami containers for heating food. You get the same results without the dioxins. So such things as TV dinners, instant Ramen and soups, etc., should be removed from the container and heated in something else. Paper isn't bad but you don't know what is in the paper. Just safer to use tempered glass, Corning Ware, etc. He said we might remember when some of the fast food restaurants moved away from the foam containers to paper. The dioxin problem is one of the reasons. To add to this: Saran wrap placed over foods as they are nuked, with the high heat, actually drips poisonous toxins into the food! Use a paper towel!"
Reprinted with permission of Claire Nelson"
Microwave Ovens & Superheating
What is superheating?
In this context superheating means the heating of a liquid to a temperature above its normal boiling point. The superheated state is unstable, and it can very rapidly turn into liquid at the boiling point, plus a substantial quantity of vapour.
Why is it dangerous?
If one litre of water is superheated by only 1 °C (ie if it is heated to 101 °C without boiling), it is in an unstable state, and it can suddenly produce about 3 litres of steam. The rapid production of a substantial quantity of steam within the bulk of the water will cause it to boil vigorously and possibly to appear to explode. The result is boiling water flying at speed out of the container.
Why does it occur to a greater degree in microwave ovens than in saucepans or kettles?
In a microwave oven, the water is usually hotter than the container, whereas parts of the kettle or saucepan are usually hotter than the water. Further, the surfaces of some containers used in microwave ovens may be very smooth, almost at a molecular scale, whereas this is not true for kettles or saucepans.
Microwave ovens heat the water directly: the microwaves pass through the container and the water, and the water itself absorbs energy from them. In a kettle or saucepan, the container itself (saucepan) or a heating element (some kettles) is hotter than the water. The hottest points cause a small amount of local superheating, boiling is initiated here, and this then stirs the water.
Why is it possible to heat water above its boiling temperature?
Let us talk only about pure water, and only water at or close to atmospheric pressure.
At the surface between air and water, or between steam and water, water boils at 100 °C. Water boils at 100 °C if there is already a bubble of steam (or air) present. But in the absence of bubbles, water can be heated above 100 °C. There are two reasons. First, to make a stable bubble, a lot of water molecules in the same small area must form steam. This is improbable. Second, it takes extra energy to form the bubble itself: energy to push the water out of the way, and energy to make the surface between water and steam. Once a bubble forms (a process called nucleation), it is easy to increase its size. So the superheated water nearby evaporates very quickly, producing a large volume of steam.
Smooth containers do not have bubbles of air clinging to their sides. Rough walled or scratched containers may hold microscopic bubbles in their cracks. These become nucleii for boiling. Even a crack that is fully filled with water can be a boiling nucleus because it reduces the required area of the water-vapour surface.
Quantitative superheating details
The latent heat of vapourisation of water is L = 2.23 MJ/kg. This means that it takes 2,230,000 Joules of heat to evaporate 1 kg of water at 100 °C and at normal atmospheric pressure. (One kilogramme of water is about one litre.)
The specific heat capacity of water is c = 4.2 kJ/kg. This means that it takes 4,200 Joules of heat to raise the temperature of 1 kg of water by 1 °C.
Suppose that we heat one kilogram of water from 100 °C (its normal boiling temperature) to 101 °C, i.e. it is now superheated by 1 °C. When it begins to boil, it will very quickly cool to 100 °C, and the heat liberated turns water into steam. Cooling this kg of water by 1 °C gives 4.2 kJ, which is enough to evaporate c/L = 4200/2230000 kg of water. This is only 1.9 millilitres of water, which does not sound very much, but it turns into 3 litres of steam. Those three litres of steam are created insidethe hot water, quite suddenly, so the water is ejected violently from the container.
Microwave Superheating & When does it happen?
The following conditions promote these potentially dangerous events:
1.Using a container with a very smooth surface, such as an unscratched glass or glazed container.
2.Heating for too long.
3.Quickly adding a powder, such as instant coffee (or sometimes even an object to stir it).
4.Standing with one's face above the container makes injury more likely.
How superheating can be dangerous:
You put water in a new mug (one that has no cracks in the internal glazing and which has never been scoured). You put it in the oven with a setting that is a little too long for the amount of water. While it is heating the phone rings. You return some time later, decide to reheat it, so you restart the oven. You take out the cup and immediately add a spoonful of instant coffee. The water boils vigorously, throwing boiling water over your arm and face.
How you can avoid superheating:
1.Before putting the water into the oven, insert a non-metal object with a surface that is not smooth. (e.g. a wooden stirrer. A wooden skewer or icecream stick will do.)
2.Use a container whose surface is at least a little scratched.
3.Do not heat for longer than the recommended time for the quantity of water used.
4.Tap the outside of the container a few times with a solid object while it is still in the oven. Use a long object so that your hand remains outside the oven. Alternatively, and still keeping your hand outside the oven, insert a stirrer while the container is still in the oven. (Thus, if vigorous boiling occurs, most of the boiling water will strike the inside of the oven.)
5.Keep your face well away from the open oven door and from the container.
All of these precautions should reduce the chance or extent of superheating and resultant injury. Nevertheless, very hot water is always dangerous and one should always treat it with caution.
Potential dangers associated with microwave ovens
Microwave Sparks & Fires
Electrical conductors, such as aluminium foil, cutlery, even gold leaf on plates, should not be used in microwave ovens. These conductors concentrate the electric field and so can produce sparks. The sparks in turn may cause a fire.
1. Do not put metals in the microwave oven.
2. Do not heat falmmable or explosive materials in a microwave oven.
3. Wood & paper items can catch on fire if microwaved at too high a setting or for too long a period of time.
Uneven Heating
Partly because the electromagnetic field in a loaded oven is not uniform, and partly because they heat quickly, microwave ovens can give rise to uneven heating. When we take food out of a normal oven, we expect the outside to be at least as hot as the inside. With a microwave oven, the reverse is often true: the liquid inside is hotter than its container. Users may underestimate the temperature and thus cause burns.
1. Be aware that high temperatures may be present, even if the container is only warm.
Steam Dangers
A gram of steam at 100°C contains more heat than a gram of boiling water, and so may produce more severe burns. If food is heated in a sealed container, this can produce steam inside the container. When released, the steam, perhaps under a small pressure excess, may burn the user.
1. Do not heat things in sealed containers
2. If the instructions say 'leave to cool', then do so!
Microwave Leakage
Microwave ovens are usually made of metal, and there is a metal screen in the door. An automatic switch turns the oven off when the door is opened. Thus, when microwaves are radiated into the oven, the volume is almost completely surrounded by electrical conductor, which means that the microwaves are reflected rather than being transmitted to thespace outside. ('Almost' is there because the screen in the door usually has small holes to allow the user to look in. These holes are much smaller in size than the wavelengths used and so very little energy is radiated through these holes.)
If it were possible to turn the oven on with the door open, a beam of microwaves would radiate through the open door. This beam would be dangerous: it would rapidly heat up human tissue (just like cooking meat) and could have other health effects as well.
1. Never disconnect the automatic safety switch
2. If the door or the case of the oven are damaged, either discard the device or have it checked for microwave leakage.
Sources:
How Things Work: Microwave Ovens
By:rof Louis A. Bloomfield, University of Virginia
http://www.microwavenews.com/
http://boston.indymedia.org/newswire/display/204067/index.php
http://www.phys.unsw.edu.au/~jw/superheating.html#when
http://rabi.phys.virginia.edu/HTW//microwave_ovens.html
http://www.phys.unsw.edu.au/~jw/superheating.html#when
Copyright © 2007 Donald R Houston, PhD. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed without the author's consent.
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