TERM PAPER

MICROWAVE OVENS

BY

PALAK MEHRA

11002346

ACKNOWLEDGEMENT

TABLE OF CONTENTS

INTRODUCTION

HISTORY

WORKING PRINCIPLE

USE IN TODAYS WORLD

ADVANTAGES

DISADVANTAGES

FUTURE OF MICROWAVE OVENS

INTRODUCTION

Microwave oven is an electromagnetic wave with a wavelength in the range 0.001–0.3 m, shorter than that of a normal radio wave but longer than those of infrared radiation. Microwaves are used in radar, in communications, and for heating in microwave ovens and in various industrial processes.

When people think of microwave ovens, they think about the fact that they are everywhere. They think about the fact that most of the things that they cook and heat will come out of the microwave and use the technology. Microwave ovens are one of the most popular ways to cook and heat food. While there are multiple types of microwaves, and different ways to use a microwave oven, all of them do nearly the same thing. While microwave ovens will all do the same thing, there are different types of microwaves to choose from.

Some of the microwaves simply look different, as they have been given a sharper and cleaner design to fit in a more upscale type of kitchen, while others will tweak how the microwave works, especially with how fast it can work. These tweaks and changes aim to help those who are actually purchasing the microwave. The over-the range microwave was one of the most important changes that the microwave has ever seen. Putting the microwave over the range actually helped to bring the microwave into the kitchen in a way that did not take up counter or shelf space. This was important, as it solidified the microwave's stance as a major kitchen appliance, despite its size.

One of the other major changes to the small appliances is the strength of the microwave. While certain microwaves will have different strengths of their own, some microwaves will simply have higher strengths than others. This turns some microwaves into major appliances, as some microwaves can heat things in a faster and more efficient way .There are a few important things that you should take into consideration before you actually purchase a new microwave oven. While the microwave is partially about the look (and the overall feel of the entire kitchen itself), there are many more aspects that many people will not even consider, but could actually affect how happy you are with your microwave purchase.

Microwaves are low on the electromagnetic spectrum. The electromagnetic spectrum is a range of all the possible electric radiation. Frequency of a wave is the number of waves per second and the frequency of a m. Microwave is between 300 MHz and 300 GHz. The wavelength of a wave is the distance from one peak of a wave to the peak of a following wave and a wavelength of a microwave varies from one millimeter to thirty centimeters. The frequencies range from ultra high frequency to super high frequency to extremely high frequency. The microwave was discovered by Heinrich Hertz and predicted by James Clerk Maxwell. In 1864, James Clerk Maxwell theorized about microwaves until he predicted equations that would prove the existence of microwaves. In 1888, Heinrich Hertz took these equations and used them in an experiment. He made an apparatus that produced waves and detected these waves. The experiment displayed the different wavelengths of certain waves, such as the short wavelength of microwaves. The discovery of microwaves permitted it to be used for commercial purposes.

Microwave ovens are the best example of a commercial usage of microwaves. Microwave ovens use microwaves at a frequency of 2450 MHz. The Microwaves travel cause the water, fat, and sugars to vibrate resulting in the food’s temperature rising. This type of energy is called Dielectric energy. This benefits the food making process and anyone who buys TV dinners. Another instance of microwaves is cell phones. Cell phones use an antenna and a little transmitter to connect to the microwaves emitted in the air. To make cell phones more attractive for buyers, they minimized the transmitters and antennas. The microwaves used in phones make it possible for a person to receive calls from any location, this is especially important in emergencies. Broadcasting transmissions, such as cable TV and the Internet, use microwaves to transmit the signal in order to broadcast. These two sources that use microwaves permit faster communication between all areas of the world. These two sources that use microwaves are the most popular ways of entertainment for most of the United States. The commercial industry benefits from these products that use microwaves.

Current studies prove indecisive about the effects of microwaves. Microwave ovens can cause damage to the eyes. If a person were to press their face on the microwave oven, it can cause cataracts in the eyes. The best advice to protect against this effect is to stay a couple feet away according to Dr. Joseph Mercola. The most controversial issue about microwaves is if they have a hazardous effect on the brain through cell phone usage. Some people believe that having a mobile phone near the ear for a prolonged period of time will cause cancer, or a brain tumor due to the microwaves that are transmitted. According to the article “MIRROR, MIRROR, Fearing Rads, Cell Addicts Sprout Wires” in The New York Times, “No studies directly link cell phone use to brain cancer…” A piece of advice that most doctors would give to patients concerned with the microwaves form their cell phones is to only use it when necessary. However, studies have not proven anything that is accurate at this point in time, they are still in the process of being conducted.

Microwaves allow the world to progress. They help people communicate faster and more effectively. Experiments are still continuing to figure out the real dangers of these waves. Microwaves are one of the most used waves for commercial uses. Microwaves surround our everyday activities.

Radio Waves

Radio waves are the oscillations of magnetic waves by varying the modulation to generate different signals which can be converted into information such as sound, video, or digital communication. As these waves pass through a conductor, an alternating current is generated and this can be converted into usable information.

As one could see from the picture above, radio waves are the electromagnetic waves with wave lengths between 1mm and 10 Mm. This converts to a frequency range of 300 GHz to 30GHz, respectively.

Nearly everyone uses radio waves in some form day after day. The technologies that depend on them is vast and ever-growing. These technologies range from cordless phones and garage door openers to radar and microwave ovens. Radio is not a dead technology either. It is constantly having research devoted to it and new technologies and innovations are coming about from this research. The trend towards wireless internet and more versatile cellular phones are just some examples. Ironically, the

fundamentals of radio waves are relatively simple (at least when compared to the vast array of technologies that now implement it).

Cordless phones use radio waves to allow individuals to walk around freely in their home without the need to be bound by a cord while talking over their land-based phone line.

Cell phones are a miracle to modern day living. Unlike previous eras where communication was done strictly across a hard-wired telephone line, cell phones now give the freedom to those that can afford them a radio-based uplink to the rest of the world. Not only are they for voice communication, but they also allow for transmission of virtually any kind of digital data.

Microwave ovens are another great invention from the 20th century. They use radio waves in a specific frequency range in which water, fat, and sugar molecules happen to absorb and convert directly into heat. This frequency range also happens to move right through glass and most plastics. Unfortunately, metal reflects radio waves thus causing issues while trying to use a metal pan or bowl .

There are numerous more technologies that are also either based off of or incorporate radio waves in their design, far too many to list.

The microwave oven recently celebrated its golden anniversary. As familiar an appliance as it is to many people, few really know how it works. This article will provide some insight into the history of the microwave oven’s discovery and development, as well as elaborate on the internal workings and mechanisms that provide the "magic" behind the function of this seemingly mysterious box.

History

In today's technology-driven world, almost everyone, at some point in their lives, has either used or had some sort of contact with a microwave oven (see Fig. 1). Popular opinion was not always so overwhelmingly supportive of this breakthrough technology, as the microwave oven initially struggled to gain acceptance since its inception over fifty years ago.

Like many of the great inventions of our past, the idea behind the microwave oven was accidentally stumbled upon in 1946. Dr. Percy Spencer was working as an engineer with the Raytheon Corporation at the time, when he discovered something very unusual one day while working on a radar-related research project. While testing a new vacuum tube known as a magnetron, he discovered that a candy bar in his pocket had melted. Intrigued as he was, Spencer decided upon further experimentation. Later on, having pointed the tube at such objects as a bag of popcorn kernels and an egg, with similar results in both experiments (the popcorn popped and the egg exploded), he correctly concluded that the observed effects in each case were all attributed to exposure to low-density microwave energy [2]. Shortly after the accidental discovery, engineers at Raytheon went to work on Spencer's new idea, developing and refining it to be of practical use.

In late 1946, this resulted in the Raytheon Company's first patent proposing that microwaves be used to cook food. The following year, the first commercial microwave oven, dubbed the "Radarange," hit the market with a cost between $2,000 and $3,000. Finally in 1965, Raytheon introduced the first

countertop domestic oven, much improved in the area of size, safety and reliability than older models with a cost of $500. As fears and myths of these mysterious new "radar ranges" began to fade during the 1970's, public demand began to swell with acceptance until the sales of microwave ovens eventually surpassed those of gas ranges in 1975. Furthermore, in 1976 the microwave became a more common household appliance than the dishwasher as it found its home in nearly fifty-two million U.S. households, or 60% of U.S. homes [2].

Christian Rasmussen/Wikimedia Commons

Figure 1: Modern microwave ovens have come a long way from their original counterparts.

Early theories

It was an invention that related to heating systems for dielectric materials and the object of the invention was to heat such materials uniformly and substantially simultaneously throughout their mass. It has been proposed therefore to heat such materials simultaneously throughout their mass by means of the dielectric loss produced in them when they are subjected to a high voltage, high frequency field.

However, lower-frequency dielectric heating, as described in the aforementioned patent, is (like induction heating) an electromagnetic heating effect, which itself is the result of the so-called near-field effects that exist in an electromagnetic cavity that is small compared with the wavelength of the electromagnetic field. This patent proposed radiofrequency heating, at 10 to 20 megahertz (wavelength 15 to 30 meters).[2] Heating from microwaves that have a wavelength that is small in relation to the cavity (as in a modern microwave oven) is due to "far-field" effects that are due to classical electromagnetic radiation that describes freely propagating light and microwaves suitably far from their source. Nevertheless, the primary heating effect of all types of electromagnetic fields at both radio and microwave frequencies occurs via the dielectric heating effect, as polarized molecules are affected by a rapidly alternating electric field.

Accidental discovery

The specific heating effect of a beam of high-power microwaves was discovered accidentally in 1945, shortly after high-powered microwave radar transmitters were developed and widely disseminated by the Allies of World War II, using the British magnetron technology that was shared with the United States company Raytheon in order to secure production facilities to produce the magnetron. Percy Spencer, an American self-taught engineer from Howland, Maine, worked at the time with Raytheon. He was working on an active radar set when he noticed that a Mr. Goodbar he had in his pocket started to melt - the radar had melted his chocolate bar with microwaves. The first food to be deliberately cooked with Spencer's microwave was popcorn, and the second was an egg, which exploded in the face of one

of the experimenters.[3][4] To verify his finding, Spencer created a high density electromagnetic field by feeding microwave power from a magnetron into a metal box from which it had no way to escape. When food was placed in the box with the microwave energy, the temperature of the food rose rapidly.

On October 8, 1945,[5] Raytheon filed a US patent for Spencer's microwave cooking-process, and an oven that heated food using microwave energy from a magnetron was soon placed in a Boston restaurant for testing. The first time the public was able to use a microwave oven was in January 1947, when the Speedy Weeny vending machine was placed in Grand Central Terminal to dispense "sizzling delicious" hot dogs. Among those on the development team was robotics pioneer George Devol, who had spent the last part of the war developing radar countermeasures.

Commercial availabilityIn 1947, Raytheon built the "Radarange", the first commercially available microwave oven.[6] It was almost 1.8 metres (5 ft 11 in) tall, weighed 340 kilograms (750 lb) and cost about US$5,000 ($52,273 in today's dollars) each. It consumed 3 kilowatts, about three times as much as today's microwave ovens, and was water-cooled. An early Radarange was installed (and remains) in the galley of the nuclear-powered passenger/cargo ship NS Savannah. An early commercial model introduced in 1954 consumed 1.6 kilowatts and sold for US$2,000 to US$3,000 ($17,000 to $26,000 in today's dollars). Raytheon licensed its technology to the Tappan Stove company of Mansfield, Ohio in 1952.[7] They tried to market a large, 220 volt, wall unit as a home microwave oven in 1955 for a price of US$1,295 ($11,285 in today's dollars), but it did not sell well. In 1965, Raytheon acquired Amana. In 1967, they introduced the first popular home model, the countertop Radarange, at a price of US$495 ($3,465 in today's dollars).

In the 1960s, Litton bought Studebaker's Franklin Manufacturing assets, which had been manufacturing magnetrons and building and selling microwave ovens similar to the Radarange. Litton then developed a new configuration of the microwave: the short, wide shape that is now common. The magnetron feed was also unique. This resulted in an oven that could survive a no-load condition, or an empty microwave oven where there is nothing to absorb the microwaves. The new oven was shown at a trade show in Chicago,[citation needed] and helped begin a rapid growth of the market for home microwave ovens. Sales volume of 40,000 units for the US industry in 1970 grew to one million by 1975. Market penetration was faster in Japan, due to a re-engineered magnetron allowing for less expensive units. Several other companies joined in the market, and for a time most systems were built by defense contractors, who were most familiar with the magnetron. Litton was particularly well known in the restaurant business.

By the late 1970s, the technology had improved to the point where prices were falling rapidly. Often called "electronic ovens" in the 1960s, the name "microwave ovens" later became standardized, often now referred to informally as simply "microwaves".

Formerly found only in large industrial applications, microwave ovens increasingly became a standard fixture of residential kitchens. The rapidly falling price of microprocessors also helped by adding electronic controls to make the ovens easier to use.[citation needed] By 1986, roughly 25% of households in the U.S. owned a microwave oven, up from only about 1% in 1971.[8] The U.S. Bureau of Labor Statistics reported that over 90% of American households owned a microwave oven in 1997.[8][9]

Working principle

Why does our food go in cold and come out hot? The answer to this question is a multi-faceted one, involving both physics and engineering. In discovering how a microwave oven works, we must first understand the basic physical concept of electromagnetic waves. All electromagnetic (EM) waves are characterized by both a wavelength and a frequency. To help in visualizing this concept, envision yourself standing on a curb somewhere, watching an oscillating EM wave pass before you. The wavelength (in meters) can be found by measuring the length of one complete cycle of the wave, while the frequency (in seconds-1) can be determined by keeping track of how often those cycles pass in front of you.

The relationship that forms results in the creation of an electromagnetic spectrum, composed of a wide variety of different wavelengths and corresponding frequency values. However, while each electromagnetic wave has a different corresponding wavelength and frequency, the product of these two components always equals the speed of light (roughly, 3.0 x 108 meters/second) [3]. Microwaves correspond to a region in the EM spectrum defined by having wavelengths between approximately 1 meter and 1 millimeter, corresponding to frequencies between 300 MHz (Mega = 106 Hz = 106 sec-1) and 300 GHz (Giga = 109).

A microwave oven works by passing non-ionizing microwave radiation through the food. Microwave radiation is between common radio and infrared frequencies, being usually at 2.45 gigahertz (GHz)—a wavelength of 122 millimetres (4.80 in)—or, in large industrial/commercial ovens, at 915 megahertz (MHz)—328 millimetres (12.9 in).[10] Water, fat, and other substances in the food absorb energy from the microwaves in a process called dielectric heating. Many molecules (such as those of water) are electric dipoles, meaning that they have a partial positive charge at one end and a partial negative charge at the other, and therefore rotate as they try to align themselves with the alternating electric field of the microwaves. Rotating molecules hit other molecules and put them into motion, thus

dispersing energy. This energy, when dispersed as molecular vibration in solids and liquids (i.e., as both potential energy and kinetic energy of atoms), is heat. Sometimes, microwave heating is explained as a resonance of water molecules, but this is incorrect;[11] such resonances occur only at above 1 terahertz (THz).[12]

Microwave heating is more efficient on liquid water than on frozen water, where the movement of molecules is more restricted. Dielectric heating of liquid water is also temperature-dependent: At 0 °C, dielectric loss is greatest at a field frequency of about 10 GHz, and for higher water temperatures at higher field frequencies.[13]

Compared to liquid water, microwave heating is less efficient on fats and sugars (which have a smaller molecular dipole moment).[14] Sugars and triglycerides (fats and oils) absorb microwaves due to the dipole moments of their hydroxyl groups or ester groups. However, due to the lower specific heat capacity of fats and oils and their higher vaporization temperature, they often attain much higher temperatures inside microwave ovens.[13] This can induce temperatures in oil or very fatty foods like bacon far above the boiling point of water, and high enough to induce some browning reactions, much in the manner of conventional broiling (UK: grilling) or deep fat frying. Foods high in water content and with little oil rarely exceed the boiling temperature of water.

Used extensively in communications due to their relatively short wavelengths, microwaves are often used to transmit data from satellites in space to satellite dishes on Earth. A satellite dish reflects microwaves because it is made of metal. A tighter grasp of how this "reflection" works lies in understanding the interactions that occur between the two mediums. As an EM wave hits the surface of the metal, mobile charges inherent within the metal itself are accelerated by the EM wave's electric field, thereby preventing the wave from entering the surface and reflecting it instead [3]. As we will see, this concept, among others, readily contributes to the design of the microwave oven.

Now that we understand the essence of microwaves, we can focus our attention specifically on how a microwave oven heats food. The underlying principle behind the technology that makes microwave ovens a reality depends heavily on the fact that water molecules are electrically polar in nature-they have both positively and negatively charged ends. These polar characteristics stem from the quantum mechanical structure of water as well as the tendency for oxygen to pull electrons away from the hydrogen atoms. Having a "bent" geometry, the water molecule looks similar to Mickey Mouse's head with its two hydrogens sticking out from the lone oxygen. As the oxygen pulls electrons away from the hydrogens a partial negative charge begins to form on the oxygen end of the molecule, while the hydrogen ends change to accommodate a partial positive charge. Thus water can be considered a polar molecule. In ice, the movement of water molecules is very constrained due to the organization of the molecules into rigid structures and orientations. But in its liquid phase, the molecules move around much more freely, with orientations being much more random in nature.

When water is placed in the presence of a strong electric field, the water molecules tend to rotate themselves into alignment with their positive ends in the direction of the field. Consequently, in their rotation they often "bump" into other water molecules, which in turn transfers some of the molecule's electrostatic potential energy into thermal energy. An analogy would be a very crowded room, when everyone is told to turn and face the stage. In doing so, people brush up against one another as they turn and friction causes the conversion of some of their energy into thermal energy. If this action were to happen over and over, people would get extremely warm. The same idea is true for water. By reversing the direction of the electric field many times, water molecules spin backwards and forward, getting hotter and hotter each time. It is this thermal energy that cooks the food. Microwave ovens use 2.45 GHz microwaves to flip water molecules back and forth at a rate of over a billion times per second. This particular frequency was chosen because it was not in use for communications and because it provided just enough time to allow a water molecule to flip, before the field reverses its direction [3].

In its most basic form, the microwave oven comprises of several key components, each playing an important role in the overall functionality of the unit. To create the specific EM waves needed, with an exact frequency of 2.45 GHz, microwave ovens utilize a special vacuum tube called a magnetron. In short, a magnetron allows for streams of electrons to make charges (positive and negative) "slosh" in several microwave "tank" circuits that have the necessary resonant frequency, 2.45 GHz, to produce the target microwaves. Enlisting the help of a short antenna, the magnetron emits the microwaves that cook the food. Arranged in a circle, the microwave tank circuits, comprising of both an inductor and a capacitor, form the outer edge of the magnetron. Each C-shaped circuit is oriented in such a way as to resemble several people spaced evenly (yet close together, to stay warm!) around a blazing campfire on a cold night.

The capacitor section of the circuit consists of the two "arms" where separated charges initially reside (positive and negative charges, respectively on each arm), while the curved part of the circuit plays the role of the inductor, which resists changes in the circuit's current. To illustrate the process by which this "circle of C's" operates, let us simply envision one tank circuit by itself (picture a giant "C"). Under initial conditions, charge separation is in place with positive charges residing on the top arm, while negative charges occupy the bottom one. The charge begins to flow producing current from the positive end to the negative end. This current produces a magnetic field that flows in an upward, perpendicular direction in reference to the movement of electrons. For our purposes, in relation to our "C," the orientation of the field would be upward and out of the plane of our paper, as if threatening to poke us in the nose. The strength of the field then grows until the separated charge at the capacitor side is eventually all gone. At this point, harnessing the potential energy stored within the magnetic field and wanting to keep the current constant, the inductor begins to propel charges through the strip even after the initial charge separation found on the capacitor end has completely dissipated. Eventually the magnetic field dies away, but not before the initial conditions of charge separation are once again realized, only this time-upside-down (our "C" would now have a negatively charge top arm, instead of a positive one, etc.). Thus the process is allowed to repeat while reversing direction [3].

This oscillation of currents at a resonant frequency of 2.45 GHz creates an environment of alternating electric and magnetic fields within the magnetron. Due to this characteristic, the microwave tank circuit

is known as a resonant cavity or resonator [3]. In a typical microwave oven, the magnetron contains eight resonators, assembled in a ring, with each of their tips touching the tips of their neighbor's (remember the campfire analogy). Another important factor arises in the discussion of the importance of materials used in microwave construction that contribute to its efficiency and functionality. As is such in any case of design or creation, the selection of materials must be carefully considered in light of the various advantages and disadvantages that are inherent within each substance. Due to the limitations of copper as an electrical conductor, a portion of the generated energy is lost during the "microwave wave-making" process in the form of heat. To make up for this loss, as well as adjust for the energy expended in cooking the food, power is supplied to the resonators in the form of a stream of electrons [3]. At the center of the ring of resonators lies the source of that stream in the form of a cathode, a negatively charged filament that is connected to a high voltage power supply. The power supply electrically "pumps" the filament with negative charges, inducing a strong electric field that originates from four surrounding, positive resonator tips. The direction of the field is established by convention to point towards the direction that positively charged particles flow when subjected to the field.

There also exists within the magnetron a strong magnetic field, generated by a nearby large permanent magnet. Much like our earlier example, the field would extend upward, and out of the plane of a piece of paper if we were looking at the magnetron from above. If left to operate by itself, the magnetic field would undoubtedly accelerate the many electrons contained on the "hot" cathode in a counter-clockwise direction, never approaching the resonators. In real life, both the electric field and the magnetic field are present at the same time.

Since both of these fields apply forces to the moving electrons, the ensuing stream of charges is rather complicated in nature. Merging the two initial forces, outward and circular, the resultant force takes the form of something resembling a spinning bicycle wheel, with four outwardly bent electron beams rotating in a counter-clockwise motion [3]. The main difference is that the electron beams now reach the resonators, not at their positively charged tips (which would be the case without the magnetic field), but at their negatively charged tips. Therefore, the net effect is one of addition to the charge separation in the resonators [3].

With each oscillation of charge that takes place on the resonators, the electron beams rotate with perfect synchronization, such that they always land on a negatively charged tip. By helping to increase the charge separation, they in turn boost the power needed for oscillations in the resonators and allow the transfer of energy to the food to continue The power of the oscillating charges are harnessed by a small wire coil placed within the cavity of the magnetron, from which a 2.45 GHz alternating current is induced due to the changing magnetic field. This current is then translated to a small antenna, which emits microwaves into a metal pipe attached to the cooking chamber. The waves then reflect along until they reach the chamber where they proceed to cook the food.

Conclusion

The microwave oven has taken its time in establishing a place for itself among the many other appliances that adorn the kitchen countertops of today. Yet while its usefulness and capabilities are

often well known, the intricacies of its design and inner workings are not. Hopefully in the future, this "imbalance" of understanding will shift more towards enlightenment as more and more people come to realize that the only real "magic" within a microwave oven is the engineering behind it.

References

[1] B. Anslow. "Melted Chocolate to Microwave." Tech Review, vol. 120(1), 1999.

[2] C.J. Gallawa The Complete Microwave Oven Service Handbook., 2000.

[3] L.A. Bloomfield. How Things Work: The Physics of Everyday Life. New York: John Wiley and Sons, Inc. 1997

Radiation Ovens

The Proven Dangers of Microwaves

Is it possible that millions of people are ignorantly sacrificing their health in exchange for the convenience of microwave ovens? Why did the Soviet Union ban the use of microwave ovens in 1976? Who invented microwave ovens, and why? The answers to these questions may shock you into throwing your microwave oven in the trash.

Over 90% of American homes have microwave ovens used for meal preparation. Because microwave ovens are so convenient and energy efficient, as compared to conventional ovens, very few homes or restaurants are without them. In general, people believe that whatever a microwave oven does to foods cooked in it doesn't have any negative effect on either the food or them. Of course, if microwave ovens were really harmful, our government would never allow them on the market, would they? Would they? Regardless of what has been "officially" released concerning microwave ovens, we have personally stopped using ours based on the research facts outlined in this article.

The purpose of this report is to show proof - evidence - that microwave cooking is not natural, nor healthy, and is far more dangerous to the human body than anyone could imagine. However, the microwave oven manufacturers, Washington City politics, and plain old human nature are suppressing the facts and evidence. Because of this, people are continuing to microwave their food - in blissful ignorance - without knowing the effects and danger of doing so.

How do microwave ovens work?

Microwaves are a form of electromagnetic energy, like light waves or radio waves, and occupy a part of the electromagnetic spectrum of power, or energy. Microwaves are very short waves of electromagnetic energy that travel at the speed of light (186,282 miles per second). In our modern technological age, microwaves are used to relay long distance telephone signals, television programs, and computer information across the earth or to a satellite in space. But the microwave is most familiar to us as an energy source for cooking food.

Every microwave oven contains a magnetron, a tube in which electrons are affected by magnetic and electric fields in such a way as to produce micro wavelength radiation at about 2450 Mega Hertz (MHz) or 2.45 Giga Hertz (GHz). This microwave radiation interacts with the molecules in food. All wave energy changes polarity from positive to negative with each cycle of the wave. In microwaves, these polarity changes happen millions of times every second. Food molecules - especially the molecules of water - have a positive and negative end in the same way a magnet has a north and a south polarity.

In commercial models, the oven has a power input of about 1000 watts of alternating current. As these microwaves generated from the magnetron bombard the food, they cause the polar molecules to rotate at the same frequency millions of times a second. All this agitation creates molecular friction, which heats up the food. The friction also causes substantial damage to the surrounding molecules, often tearing them apart or forcefully deforming them. The scientific name for this deformation is "structural isomerism".

By comparison, microwaves from the sun are based on principles of pulsed direct current (DC) that don't create frictional heat; microwave ovens use alternating current (AC) creating frictional heat. A microwave oven produces a spiked wavelength of energy with all the power going into only one narrow frequency of the energy spectrum. Energy from the sun operates in a wide frequency spectrum.

Many terms are used in describing electromagnetic waves, such as wavelength, amplitude, cycle and frequency:

Wavelength determines the type of radiation, i.e. radio, X-ray, ultraviolet, visible, infrared, etc.

Amplitude determines the extent of movement measured from the starting point.

Cycle determines the unit of frequency, such as cycles per second, Hertz, Hz, or cycles/second.

Frequency determines the number of occurrences within a given time period (usually 1 second); The number of occurrences of a recurring process per unit of time, i.e. the number of repetitions of cycles per second.

Radiation = spreading energy with electromagnetic waves

Radiation, as defined by physics terminology, is "the electromagnetic waves emitted by the atoms and molecules of a radioactive substance as a result of nuclear decay." Radiation causes ionization, which is what occurs when a neutral atom gains or loses electrons. In simpler terms, a microwave oven decays and changes the molecular structure of the food by the process of radiation. Had the manufacturers accurately called them "radiation ovens", it's doubtful they would have ever sold one, but that's exactly what a microwave oven is.

We've all been told that microwaving food is not the same as irradiating it (radiation "treatment"). The two processes are supposed to use completely different waves of energy and at different intensities. No FDA or officially released government studies have proven current microwaving usage to be harmful, but we all know that the validity of studies can be - and are sometimes deliberately - limiting. Many of these studies are later proven to be inaccurate. As consumers, we're supposed to have a certain degree of common sense to use in judgment.

Take the example of eggs and how they were "proven" to be so harmful to our health in the late 1960's. This brought about imitation egg products and big profits for the manufacturers, while egg farms went broke. Now, recent government sponsored studies are saying that eggs are not bad for us after all. So, whom should we believe and what criteria should we use to decide matters concerning our health? Since it's currently published that microwaves - purportedly - don't leak into the environment, when properly used and with approved design, the decision lies with each consumer as to whether or not you choose to eat food heated by a microwave oven or even purchase one in the first place.

Motherly instincts are right

On a more humorous side, the "sixth sense" every mother has is impossible to argue with. Have you ever tried it? Children will never win against a mother's intuition. It's like trying to argue with the arm - appearing out of nowhere - that pinned you to the back of the seat when your mother slammed on the brakes.

Many of us come from a generation where mothers and grandmothers have distrusted the modern "inside out" cooking they claimed was "not suitable" for most foods. My mother refused to even try baking anything in a microwave. She also didn't like the way a cup of coffee tasted when heated in a microwave oven. I have to fully agree and can't argue either fact.

Her own common sense and instincts told her that there was no way microwave cooking could be natural nor make foods "taste they way they're supposed to". Reluctantly, even my mother succumbed to re-heating leftovers in a microwave due to her work schedule before she retired.

Many others feel the same way, but they're considered an "old fashioned" minority dating back to before the 1970's when microwaves first overwhelmed the market. Like most young adults at the time, as microwave ovens became commonplace, I chose to ignore my mother's intuitive wisdom and joined the majority who believed microwave cooking was far too convenient to ever believe anything could be wrong with it. Chalk one up for mom's perception, because even though she didn't know the scientific, technical, or health reasons why, she just knew that microwave ovens were not good based on how foods tasted when they were cooked in them. She didn't like the way the texture of the microwaved food changed either.

Microwaves unsafe for baby's milk

A number of warnings have been made public, but have been barely noticed. For example, Young Families, the Minnesota Extension Service of the university of Minnesota, published the following in 1989:

"Although microwaves heat food quickly, they are not recommended for heating a baby's bottle. The bottle may seem cool to the touch, but the liquid inside may become extremely hot and could burn the baby's mouth and throat. Also, the buildup of steam in a closed container, such as a baby bottle, could cause it to explode. Heating the bottle in a microwave can cause slight changes in the milk. In infant formulas, there may be a loss of some vitamins. In expressed breast milk, some protective properties may be destroyed. Warming a bottle by holding it under tap water, or by setting it in a bowl of warm water, then testing it on your wrist before feeding may take a few minutes longer, but it is much safer."

Dr. Lita Lee of Hawaii reported in the December 9, 1989 Lancet:

"Microwaving baby formulas converted certain trans-amino acids into their synthetic cis-isomers. Synthetic isomers, whether cis-amino acids or trans-fatty acids, are not biologically active. Further, one of the amino acids, L-proline, was converted to its d-isomer, which is known to be neurotoxic (poisonous to the nervous system) and nephrotoxic (poisonous to the kidneys). It's bad enough that many babies are not nursed, but now they are given fake milk (baby formula) made even more toxic via microwaving."

Microwaved blood kills patient

In 1991, there was a lawsuit in Oklahoma concerning the hospital use of a microwave oven to warm blood needed in a transfusion. The case involved a hip surgery patient, Norma Levitt, who died from a simple blood transfusion. It seems the nurse had warmed the blood in a microwave oven.

This tragedy makes it very apparent that there's much more to "heating" with microwaves than we've been led to believe. Blood for transfusions is routinely warmed, but not in microwave ovens. In the case of Mrs. Levitt, the microwaving altered the blood and it killed her.

It's very obvious that this form of microwave radiation "heating" does something to the substances it heats. It's also becoming quite apparent that people who process food in a microwave oven are also ingesting these "unknowns".

Because the body is electrochemical in nature, any force that disrupts or changes human electrochemical events will affect the physiology of the body. This is further described in Robert O. Becker's book, The Body Electric, and in Ellen Sugarman's book, Warning, the Electricity Around You May Be Hazardous to Your Health.

Scientific evidence and facts

In Comparative Study of Food Prepared Conventionally and in the Microwave Oven, published by Raum & Zelt in 1992, at 3(2): 43, it states

"A basic hypothesis of natural medicine states that the introduction into the human body of molecules and energies, to which it is not accustomed, is much more likely to cause harm than good. Microwaved food contains both molecules and energies not present in food cooked in the way humans have been cooking food since the discovery of fire. Microwave energy from the sun and other stars is direct current based. Artificially produced microwaves, including those in ovens, are produced from alternating current and force a billion or more polarity reversals per second in every food molecule they hit. Production of unnatural molecules is inevitable. Naturally occurring amino acids have been observed to undergo isomeric changes (changes in shape morphing) as well as transformation into toxic forms, under the impact of microwaves produced in ovens.

One short-term study found significant and disturbing changes in the blood of individuals consuming microwaved milk and vegetables. Eight volunteers ate various combinations of the same foods cooked different ways. All foods that were processed through the microwave ovens caused changes in the blood of the volunteers. Hemoglobin levels decreased and over all white cell levels and cholesterol levels increased. Lymphocytes decreased.

Luminescent (light-emitting) bacteria were employed to detect energetic changes in the blood. Significant increases were found in the luminescence of these bacteria when exposed to blood serum obtained after the consumption of microwaved food."

The Swiss clinical study

Dr. Hans ulrich Hertel, who is now retired, worked as a food scientist for many years with one of the major Swiss food companies that do business on a global scale. A few years ago, he was fired from his job for questioning certain processing procedures that denatured the food.

In 1991, he and a Lausanne university professor published a research paper indicating that food cooked in microwave ovens could pose a greater risk to health than food cooked by conventional means. An article also appeared in issue 19 of the Journal Franz Weber in which it was stated that the consumption of food cooked in microwave ovens had cancerous effects on the blood. The research paper itself

followed the article. On the cover of the magazine there was a picture of the Grim Reaper holding a microwave oven in one of his hands.

Dr. Hertel was the first scientist to conceive and carry out a quality clinical study on the effects microwaved nutrients have on the blood and physiology of the human body. His small, but well controlled, study showed the degenerative force produced in microwave ovens and the food processed in them. The scientific conclusion showed that microwave cooking changed the nutrients in the food; and, changes took place in the participants' blood that could cause deterioration in the human system. Hertel's scientific study was done along with Dr. Bernard H. Blanc of the Swiss Federal Institute of Technology and the university Institute for Biochemistry.

In intervals of two to five days, the volunteers in the study received one of the following food variants on an empty stomach: (1) raw milk; (2) the same milk conventionally cooked; (3) pasteurized milk; (4) the same raw milks cooked in a microwave oven; (5) raw vegetables from an organic farm; (6) the same vegetables cooked conventionally; (7) the same vegetables frozen and defrosted in a microwave oven; and (8) the same vegetables cooked in the microwave oven. Once the volunteers were isolated, blood samples were taken from every volunteer immediately before eating. Then, blood samples were taken at defined intervals after eating from the above milk or vegetable preparations.

Significant changes were discovered in the blood samples from the intervals following the foods cooked in the microwave oven. These changes included a decrease in all hemoglobin and cholesterol values, especially the ratio of HDL (good cholesterol) and LDL (bad cholesterol) values. Lymphocytes (white blood cells) showed a more distinct short-term decrease following the intake of microwaved food than after the intake of all the other variants. Each of these indicators pointed to degeneration.

Additionally, there was a highly significant association between the amount of microwave energy in the test foods and the luminous power of luminescent bacteria exposed to serum from test persons who ate that food.

This led Dr. Hertel to the conclusion that such technically derived energies may, indeed, be passed along to man inductively via eating microwaved food. According to Dr. Hertel, "Leukocytosis, which cannot be accounted for by normal daily deviations, is taken very seriously by hemotologists. Leukocytes are often signs of pathogenic effects on the living system, such as poisoning and cell damage. The increase of leukocytes with the microwaved foods were more pronounced than with all the other variants. It appears that these marked increases were caused entirely by ingesting the microwaved substances.

"This process is based on physical principles and has already been confirmed in the literature. The apparent additional energy exhibited by the luminescent bacteria was merely an extra confirmation. There is extensive scientific literature concerning the hazardous effects of direct microwave radiation on living systems. It is astonishing, therefore, to realize how little effort has been taken to replace this detrimental technique of microwaves with technology more in accordance with nature.

Technically produced microwaves are based on the principle of alternating current. Atoms, molecules, and cells hit by this hard electromagnetic radiation are forced to reverse polarity 1-100 billion times a second. There are no atoms, molecules or cells of any organic system able to withstand such a violent, destructive power for any extended period of time, not even in the low energy range of milliwatts.

Of all the natural substances -- which are polar -- the oxygen of water molecules reacts most sensitively. This is how microwave cooking heat is generated -- friction from this violence in water molecules. Structures of molecules are torn apart, molecules are forcefully deformed, called structural isomerism, and thus become impaired in quality. This is contrary to conventional heating of food where heat transfers convectionally from without to within. Cooking by microwaves begins within the cells and molecules where water is present and where the energy is transformed into frictional heat.

In addition to the violent frictional heat effects, called thermic effects, there are also athermic effects which have hardly ever been taken into account. These athermic effects are not presently measurable, but they can also deform the structures of molecules and have qualitative consequences. For example the weakening of cell membranes by microwaves is used in the field of gene altering technology. Because of the force involved, the cells are actually broken, thereby neutralizing the electrical potentials, the very life of the cells, between the outer and inner side of the cell membranes. Impaired cells become easy prey for viruses, fungi and other microorganisms. The natural repair mechanisms are suppressed and cells are forced to adapt to a state of energy emergency -- they switch from aerobic to anaerobic respiration. Instead of water and carbon dioxide, the cell poisons hydrogen peroxide and carbon monoxide are produced."

The same violent deformations that occur in our bodies, when we are directly exposed to radar or microwaves, also occur in the molecules of foods cooked in a microwave oven. This radiation results in the destruction and deformation of food molecules. Microwaving also creates new compounds, called radiolytic compounds, which are unknown fusions not found in nature. Radiolytic compounds are created by molecular decomposition - decay - as a direct result of radiation.

Microwave oven manufacturers insist that microwaved and irradiated foods do not have any significantly higher radiolytic compounds than do broiled, baked or other conventionally cooked foods. The scientific clinical evidence presented here has shown that this is simply a lie. In America, neither universities nor the federal government have conducted any tests concerning the effects on our bodies from eating microwaved foods. Isn't that a bit odd? They're more concerned with studies on what happens if the door on a microwave oven doesn't close properly. Once again, common sense tells us that their attention should be centered on what happens to food cooked inside a microwave oven. Since people ingest this altered food, shouldn't there be concern for how the same decayed molecules will affect our own human biological cell structure?

Industry's action to hide the truth

As soon as Doctors Hertel and Blanc published their results, the authorities reacted. A powerful trade organization, the Swiss Association of Dealers for Electro-apparatuses for Households and Industry, known as FEA, struck swiftly in 1992. They forced the President of the Court of Seftigen, Canton of Bern, to issue a "gag order" against Drs. Hertel and Blanc. In March 1993, Dr. Hertel was convicted for "interfering with commerce" and prohibited from further publishing his results. However, Dr. Hertel stood his ground and fought this decision over the years.

Not long ago, this decision was reversed in a judgment delivered in Strasbourg, Austria, on August 25, 1998. The European Court of Human Rights held that there had been a violation of Hertel's rights in the 1993 decision. The European Court of Human Rights also ruled that the "gag order" issued by the Swiss court in 1992 against Dr. Hertel, prohibiting him from declaring that microwave ovens are dangerous to human health, was contrary to the right to freedom of expression. In addition, Switzerland was ordered to pay Dr. Hertel compensation.

Who invented microwave ovens?

The Nazis, for use in their mobile support operations, originally developed microwave "radiomissor" cooking ovens to be used for the invasion of Russia. By being able to utilize 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.

After the war, the Allies discovered medical research done by the Germans on microwave ovens. These documents, along with some working microwave ovens, were transferred to the united States War Department and classified for reference and "further scientific investigation." The Russians had also retrieved some microwave ovens and now have thorough research on their biological effects. As a result, their use was outlawed in the Soviet union. The Soviets issued an international warning on the health hazards, both biological and environmental, of microwave ovens and similar frequency electronic devices.

Other Eastern European scientists also reported the harmful effects of microwave radiation and set up strict environmental limits for their usage. The united States has not accepted the European reports of harmful effects, even though the EPA estimates that radio frequency and microwave radiation sources in America are increasing at 15% per year.

Benefits

Commercial microwave ovens all use a timer in their standard operating mode; when the timer runs out, the oven turns itself off.

Microwave ovens heat food without getting hot themselves. Taking a pot off a stove, with the exception of an induction cooktop, leaves a potentially dangerous heating element or trivet that will stay hot for some time. Likewise, when taking a casserole out of a conventional oven, one's arms are exposed to the very hot walls of the oven. A microwave oven does not pose this problem.

Food and cookware taken out of a microwave oven are rarely much hotter than 100 °C (212 °F). Cookware used in a microwave oven is often much cooler than the food because the cookware is transparent to microwaves; the microwaves heat the food directly and the cookware is indirectly heated by the food. Food and cookware from a conventional oven, on the other hand, are the same temperature as the rest of the oven; a typical cooking temperature is 180 °C (356 °F). That means that conventional stoves and ovens can cause more serious burns.

The lower temperature of cooking (the boiling point of water) is a significant safety benefit compared to baking in the oven or frying, because it eliminates the formation of tars and char, which are carcinogenic.[18] Microwave radiation also penetrates deeper than direct heat, so that the food is heated by its own internal water content. In contrast, direct heat can fry the surface while the inside is still cold. Pre-heating the food in a microwave oven before putting it into the grill or pan reduces the time needed to heat up the food and reduces the formation of carcinogenic char. Unlike frying and baking, microwaving does not produce acrylamide in potatoes,[19] however unlike deep-frying, it is of only limited effectiveness in reducing glycoalkaloid (i.e. solanine) levels.[20] Acrylamide has been found in other microwaved products like popcorn.

Heating characteristics

Microwave ovens are frequently used for reheating previously cooked food, and bacterial contamination may not be repressed if the safe temperature is not reached, resulting in foodborne illness, as with all inadequate reheating methods.

Uneven heating in microwaved food can be partly due to the uneven distribution of microwave energy inside the oven, and partly due to the different rates of energy absorption in different parts of the food. The first problem is reduced by a stirrer, a type of fan that reflects microwave energy to different parts of the oven as it rotates, or by a turntable or carousel that turns the food; turntables, however, may still leave spots, such as the center of the oven, which receive uneven energy distribution. The location of dead spots and hot spots in a microwave can be mapped out by placing a damp piece of thermal paper in the oven. When the water saturated paper is subjected to the microwave radiation it becomes hot enough to cause the dye to be released which will provide a visual representation of the microwaves. If multiple layers of paper are constructed in the oven with a sufficient distance between them a three dimensional map can be created. Many store receipts are printed on thermal paper which allows this to be easily done at home.[21] The second problem is due to food composition and geometry, and must be addressed by the cook, by arranging the food so that it absorbs energy evenly, and periodically testing and shielding any parts of the food that overheat. In some materials with low thermal conductivity, where dielectric constant increases with temperature, microwave heating can cause localized thermal runaway. Under certain conditions, glass can exhibit thermal runaway in a microwave to the point of melting.[22]

Due to this phenomenon, microwave ovens set at too-high power levels may even start to cook the edges of frozen food while the inside of the food remains frozen. Another case of uneven heating can be observed in baked goods containing berries. In these items, the berries absorb more energy than the

drier surrounding bread and cannot dissipate the heat due to the low thermal conductivity of the bread. Often this results in overheating the berries relative to the rest of the food. "Defrost" oven settings use low power levels designed to allow time for heat to be conducted within frozen foods from areas that absorb heat more readily to those which heat more slowly. In turntable-equipped ovens, more even heating will take place by placing food off-centre on the turntable tray instead of exactly in the centre.

Microwave heating can be deliberately uneven by design. Some microwavable packages (notably pies) may include materials that contain ceramic or aluminum flakes, which are designed to absorb microwaves and heat up, thereby converting microwaves to less penetrating infrared, which aids in baking or crust preparation by depositing more energy shallowly in these areas. Such ceramic patches affixed to cardboard are positioned next to the food, and are typically smokey blue or gray in colour, usually making them easily identifiable; the cardboard sleeves included with Hot Pockets, which have a silver surface on the inside, are a good example of such packaging. Microwavable cardboard packaging may also contain overhead ceramic patches which function in the same way. The technical term for such a microwave-absorbing patch is a susceptor.[23]

Effects on food and nutrients

Raisins when cooked in a microwave produce considerable smoke[citation needed]

Several studies have shown that if properly used, microwave cooking does not affect the nutrient content of foods to a larger extent than conventional heating, and that there is a tendency towards greater retention of many micronutrients with microwaving, probably due to the reduced preparation time.[24] Microwaving human milk at high temperatures is contraindicated, due to a marked decrease in activity of anti-infective factors.[25]

Any form of cooking will destroy some nutrients in food, but the key variables are how much water is used in the cooking, how long the food is cooked, and at what temperature.[26] Nutrients are primarily lost by leaching into cooking water, which tends to make microwave cooking healthier, given the shorter cooking times it requires.[27] Like other heating methods, microwaving converts vitamin B12 from an active to inactive form. The amount inactivated depends on the temperature reached, as well as the cooking time. Boiled food reaches a maximum of 100 °C (212 °F) (the boiling point of water), whereas microwaved food can get locally hotter than this, leading to faster breakdown of vitamin B12. The higher rate of loss is partially offset by the shorter cooking times required.[28] A single study indicated that microwaving broccoli loses 74% or more of phenolic compounds (97% of flavonoids), while boiling loses 66% of flavonoids, and high-pressure boiling loses 47%,[29] though the study has been contradicted by other studies.[30] To minimize phenolic losses in potatoes, microwaving should be done at 500W.[31]

Spinach retains nearly all its folate when cooked in a microwave; in comparison, it loses about 77% when cooked on stove, because food on a stove is typically boiled, leaching out nutrients. Bacon cooked by microwave has significantly lower levels of carcinogenic nitrosamines than conventionally cooked bacon.[26] Steamed vegetables tend to maintain more nutrients when microwaved than when cooked on a stovetop.[26] Microwave blanching is 3-4 times more effective than boiled water blanching in the retaining of the water-soluble vitamins folic acid, thiamin and riboflavin, with the exception of ascorbic acid, of which 28.8% is lost (vs. 16% with boiled water blanching).

A convection microwave is a combination of a standard microwave oven and a convection oven. It allows food cooked in the convection microwave to be cooked quickly, yet come out browned or crisped as in a convection oven. For example, a convection microwave oven can be preheated to bake cakes, which is not possible with standard microwave ovens. There are microwaves which contain electric browning baking elements. A true convection microwave has a high velocity forced air fan to circulate the hot air uniformly.

Convection microwave ovens were initially considered to be high-end kitchen appliances. Over time their price has dropped, and they can be bought for around the same price as a conventional oven. However, some models do require more space than a standard microwave, because of the larger cooking area inside.

Companies such as Wolf, GE, Sharp, Samsung,Panasonic and Daewoo all currently produce convection microwaves.

Convection microwaves offer the quick cooking features of a microwave with the browning, crisping, and full "cook-through" of a traditional oven. Instead of just heating the inside of the food (as regular microwaves do), a convection microwave also browns and cooks the outside of your food. Scientifically speaking, regular microwaves emit waves that bounce around until they come in contact with food, causing water molecules to excite and generate heat, which then cooks the food.

In contrast, convection oven technology uses a fan to force air movement and heat up the full interior of the microwave to cook food from the inside out. That's why you can use convection microwaves to bake and roast things that would otherwise be cooked too quickly (and not thoroughly) with just a regular microwave.

Hazards

A microwaved DVD-R disc showing the effects of electrical discharge through its metal film

High temperatures

Homogeneous liquids can superheat[33][34] when heated in a microwave oven in a container with a smooth surface. That is, the liquid reaches a temperature slightly above its normal boiling point without bubbles of vapour forming inside the liquid. The boiling process can start explosively when the liquid is disturbed, such as when the user takes hold of the container to remove it from the oven or while adding solid ingredients such as powdered creamer or sugar. This can result in spontaneous boiling (nucleation) which may be violent enough to eject the boiling liquid from the container and cause severe scalding.[35]

Closed containers, such as eggs, can explode when heated in a microwave oven due to the increased pressure from steam. Insulating plastic foams of all types generally contain closed air pockets, and are generally not recommended for use in a microwave, as the air pockets explode and the foam (which can be toxic if consumed) may melt. Not all plastics are microwave-safe, and some plastics absorb microwaves to the point that they may become dangerously hot.

Products that are heated for too long can catch fire. Though this is inherent to any form of cooking, the rapid cooking and unattended nature of microwave oven use results in additional hazard.

Metal objects

Any metal or conductive object placed into the microwave will act as an antenna to some degree, resulting in an electric current. This causes the object to act as a heating element. This effect varies with the object's shape and composition, and is sometimes utilized for cooking.

Any object containing pointed metal can create an electric arc (sparks) when microwaved. This includes cutlery, crumpled aluminum foil (though some foil used in microwaves is unsafe, see below), twist-ties containing metal wire, the metal wire carry-handles in paper Chinese take-out food containers, or almost any metal formed into a poorly conductive foil or thin wire; or into a pointed shape.[36] Forks are a good example: the tines of the fork respond to the electric field by producing high concentrations of electric charge at the tips. This has the effect of exceeding the dielectric breakdown of air, about 3 megavolts per meter (3×106 V/m). The air forms a conductive plasma, which is visible as a spark. The

plasma and the tines may then form a conductive loop, which may be a more effective antenna, resulting in a longer lived spark. When dielectric breakdown occurs in air, some ozone and nitrogen oxides are formed, both of which are unhealthy in large quantities.

A microwave oven with a metal shelf

It is possible for metal objects to be microwave-oven compatible, although experimentation by users is not encouraged. Microwaving an individual smooth metal object without pointed ends, for example, a spoon or shallow metal pan, usually does not produce sparking. Thick metal wire racks can be part of the interior design in microwave ovens (see illustration). In a similar way, the interior wall plates with perforating holes which allow light and air into the oven, and allow interior-viewing through the oven door, are all made of conductive metal formed in a safe shape.

The effect of microwaving thin metal films can be seen clearly on a Compact Disc or DVD (particularly the factory pressed type). The microwaves induce electric currents in the metal film, which heats up, melting the plastic in the disc and leaving a visible pattern of concentric and radial scars. Similarly, porcelain with thin metal films can also be destroyed or damaged by microwaving. Aluminum foil is thick enough to be used in microwave ovens as a shield against heating parts of food items, if the foil is not badly warped. When wrinkled, aluminum foil is generally unsafe in microwaves, as manipulation of the foil causes sharp bends and gaps that invite sparking. The USDA recommends that aluminum foil used as a partial food shield in microwave cooking cover no more than one quarter of a food object, and be carefully smoothed to eliminate sparking hazards.[37]

Another hazard is the resonance of the magnetron tube itself. If the microwave is run without an object to absorb the radiation, a standing wave will form. The energy is reflected back and forth between the tube and the cooking chamber. This may cause the tube to overload and burn out. For the same reason, dehydrated food, or food wrapped in metal which does not arc, is problematic for overload reasons, without necessarily being a fire hazard.

Certain foods such as grapes, if properly arranged, can produce an electric arc.[38] A naked flame, which comprises conductive plasma, will do the same. Therefore, burning candles or other burning objects should not be put into a microwave oven, unless this is the desired effect.

Some other objects that may conduct sparks are plastic/holographic print thermoses (such as Starbuck's novelty cups) or cups with metal lining. If any bit of the metal is exposed, all the outer shell will burst off the object or melt. The high electrical fields generated inside a microwave often can be illustrated by placing a radiometer or neon glow-bulb inside the cooking chamber, creating glowing plasma inside the low-pressure bulb of the device.

Direct microwave exposure

Further information: Microwave burn and Microwave#Health effects

Direct microwave exposure is not generally possible, as microwaves emitted by the source in a microwave oven are confined in the oven by the material out of which the oven is constructed. Tests have shown confinement of the microwaves in commercially available ovens to be so nearly universal as to make routine testing unnecessary.[39] According to the United States Food and Drug Administration's Center for Devices and Radiological Health, a U.S. Federal Standard limits the amount of microwaves that can leak from an oven throughout its lifetime to 5 milliwatts of microwave radiation per square centimeter at approximately 5 cm (2 in) from the surface of the oven.[40] This is far below the exposure level currently considered to be harmful to human health.[41]

The radiation produced by a microwave oven is non-ionizing. It therefore does not have the cancer risks associated with ionizing radiation such as X-rays and high-energy particles. Long-term rodent studies to assess cancer risk have so far failed to identify any carcinogenicity from 2.45 GHz microwave radiation even with chronic exposure levels, i.e., large fraction of one's life span, far larger than humans are likely to encounter from any leaking ovens.[42][43] However, with the oven door open, the radiation may cause damage by heating. Every microwave oven sold has a protective interlock so that it cannot be run when the door is open or improperly latched.

There are, however, a few cases where people have been exposed to direct microwave radiation, either from appliance malfunction or deliberate action.[44][45]

Chemical exposure

Some magnetrons have ceramic insulators with beryllium oxide (beryllia) added. The beryllium in such oxides is a serious chemical hazard if crushed and ingested (for example, by inhaling dust). In addition, beryllia is listed as a confirmed human carcinogen by the IARC; therefore, broken ceramic insulators or magnetrons should not be handled. This is obviously a danger only if the microwave oven becomes physically damaged, such as if the insulator cracks, or when the magnetron is opened and handled directly, and as such should not be a concern during normal usage.

Carcinogens in microwaved food

In Dr. Lita Lee's book, Health Effects of Microwave Radiation - Microwave Ovens, and in the March and September 1991 issues of Earthletter, she stated that every microwave oven leaks electro-magnetic radiation, harms food, and converts substances cooked in it to dangerous organ-toxic and carcinogenic products. Further research summarized in this article reveal that microwave ovens are far more harmful than previously imagined.

The following is a summary of the Russian investigations published by the Atlantis Raising Educational Center in Portland, Oregon. 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 insure sanitary ingestion. Here's a summary of some of the results:

Microwaving prepared meats sufficiently to insure sanitary ingestion caused formation of d-Nitrosodienthanolamines, a well-known carcinogen.

Microwaving milk and cereal grains converted some of their amino acids into carcinogens.

Thawing frozen fruits converted their glucoside and galactoside containing fractions into carcinogenic substances.

Extremely short exposure of raw, cooked or frozen vegetables converted their plant alkaloids into carcinogens.

Carcinogenic free radicals were formed in microwaved plants, especially root vegetables. Decrease in nutritional value.

Russian researchers also reported a marked acceleration of structural degradation leading to a decreased food value of 60 to 90% in all foods tested. Among the changes observed were:

Deceased bio-availability of vitamin B complex, vitamin C, vitamin E, essential minerals and lipotropics factors in all food tested.

Various kinds of damaged to many plant substances, such as alkaloids, glucosides, galactosides and nitrilosides.

The degradation of nucleo-proteins in meats.

Microwave sickness is discovered

The Russians did research on thousands of workers who had been exposed to microwaves during the development of radar in the 1950's. Their research showed health problems so serious that the Russians set strict limits of 10 microwatts exposure for workers and one microwatt for civilians.

In Robert O. Becker's book, The Body Electric, he described Russian research on the health effects of microwave radiation, which they called "microwave sickness." On page 314, Becker states:

"It's [Microwave sickness] first signs are low blood pressure and slow pulse. The later and most common manifestations are chronic excitation of the sympathetic nervous system [stress syndrome] and high blood pressure.

This phase also often includes headache, dizziness, eye pain, sleeplessness, irritability, anxiety, stomach pain, nervous tension, inability to concentrate, hair loss, plus an increased incidence of appendicitis, cataracts, reproductive problems, and cancer. The chronic symptoms are eventually succeeded by crisis of adrenal exhaustion and ischemic heart disease [the blockage of coronary arteries and heart attacks]."

According to Dr. Lee, changes are observed in the blood chemistries and the rates of certain diseases among consumers of microwaved foods. The symptoms above can easily be caused by the observations shown below. The following is a sample of these changes:

Lymphatic disorders were observed, leading to decreased ability to prevent certain types of cancers.

An increased rate of cancer cell formation was observed in the blood.

Increased rates of stomach and intestinal cancers were observed.

Higher rates of digestive disorders and a gradual breakdown of the systems of elimination were observed.

Microwave research conclusions

The following were the most significant German and Russian research operations facilities concerning the biological effects of microwaves:

The initial research conducted by the Germans during the Barbarossa military campaign, at the Humbolt-universitat zu Berlin (1942-1943); and, From 1957 and up to the present [until the end of the cold war], the Russian research operations were conducted at: the Institute of Radio Technology at

Kinsk, Byelorussian Autonomous Region; and, at the Institute of Radio Technology at Rajasthan in the Rossiskaja Autonomous Region, both in the union of the Soviet Socialist Republics.

In most cases, the foods used for research analysis were exposed to microwave propagation at an energy potential of 100 kilowatts/cm3/second, to the point considered acceptable for sanitary, normal ingestion. The effects noted by both German and Russian researchers is presented in three categories:

Category I, Cancer-Causing Effects

Category II, Nutritive Destruction of Foods

Category III, Biological Effects of Exposure

CATEGORY I

CANCER-CAUSING EFFECTS

[The first two points of Category I are not readable from our report copy. The remainder of the report is intact.]

3. Creation of a "binding effect" to radioactivity in the atmosphere, thus causing a marked increase in the amount of alpha and beta particle saturation in foods;

4. Creation of cancer causing agents within protein hydrolysate compounds* in milk and cereal grains [*these are natural proteins that are split into unnatural fragments by the addition of water];

5. Alteration of elemental food-substances, causing disorders in the digestive system by unstable catabolism* of foods subjected to microwaves [*the metabolic breakdown process];

6. Due to chemical alterations within food substances, malfunctions were observed within the lymphatic systems [absorbent vessels], causing a degeneration of the immune potentials of the body to protect against certain forms of neoplastics [abnormal growths of tissue];

7. Ingestion of microwaved foods caused a higher percentage of cancerous cells within the blood serum [cytomas - cell tumors such as sarcoma];

8. Microwave emissions caused alteration in the catabolic [metabolic breakdown] behavior of glucoside [hydrolyzed dextrose] and galactoside [oxidized alcohol] elements within frozen fruits when thawed in this manner;

9. Microwave emission caused alteration of the catabolic [metabolic breakdown] behavior of plant alkaloids [organic nitrogen based elements] when raw, cooked, or frozen vegetables were exposed for even extremely short durations;

10. Cancer causing free radicals [highly reactive incomplete molecules] were formed within certain trace mineral molecular formations in plant substances, and in particular, raw root-vegetables; and,

11. In a statistically high percentage of persons, microwaved foods caused stomach and intestinal cancerous growths, as well as a general degeneration of peripheral cellular tissues, with a gradual breakdown of the function of the digestive and execrative systems.

CATEGORY II

DECREASE IN FOOD VALUE

Microwave exposure caused significant decreases in the nutritive value of all foods researched. The following are the most important findings:

A decrease in the bioavailability [capability of the body to utilize the nutriment] of B-complex vitamins, Vitamin C, Vitamin E, essential minerals and lipotropics in all foods;

A loss of 60-90% of the vital energy field content of all tested foods;

A reduction in the metabolic behavior and integration process capability of alkaloids [organic nitrogen based elements], glucosides and galactosides, and nitrilosides;

A destruction of the nutritive value of nucleoproteins in meats;

A marked acceleration of structural disintegration in all foods.

CATEGORY III

BIOLOGICAL EFFECTS OF EXPOSURE

Exposure to microwave emissions also had an unpredictably negative effect upon the general biological welfare of humans. This was not discovered until the Russians experimented with highly sophisticated equipment and discovered that a human did not even need to ingest the material substance of the microwaved food substances: that even exposure to the energy-field itself was sufficient to cause such adverse side effects that the use of any such microwave apparatus was forbidden in 1976 by Soviet state law.

The following are the enumerated effects:

A breakdown of the human "life-energy field" in those who were exposed to microwave ovens while in operation, with side-effects to the human energy field of increasingly longer duration;

A degeneration of the cellular voltage parallels during the process of using the apparatus, especially in the blood and lymphatic areas;

A degeneration and destabilization of the external energy activated potentials of food utilization within the processes of human metabolism;

A degeneration and destabilization of internal cellular membrane potentials while transferring catabolic [metabolic breakdown] processes into the blood serum from the digestive process;

Degeneration and circuit breakdowns of electrical nerve impulses within the junction potentials of the cerebrum [the front portion of the brain where thought and higher functions reside];

A degeneration and breakdown of nerve electrical circuits and loss of energy field symmetry in the neuroplexuses [nerve centers] both in the front and the rear of the central and autonomic nervous systems;

Loss of balance and circuiting of the bioelectric strengths within the ascending reticular activating system [the system which controls the function of consciousness];

A long term cumulative loss of vital energies within humans, animals and plants that were located within a 500-meter radius of the operational equipment;

Long lasting residual effects of magnetic "deposits" were located throughout the nervous system and lymphatic system;

A destabilization and interruption in the production of hormones and maintenance of hormonal balance in males and females;

Markedly higher levels of brainwave disturbance in the alpha, theta, and delta wave signal patterns of persons exposed to microwave emission fields, and;

Because of this brainwave disturbance, negative psychological effects were noted, including loss of memory, loss of ability to concentrate, suppressed emotional threshold, deceleration of intellective processes, and interruptive sleep episodes in a statistically higher percentage of individuals subjected to continual range emissive field effects of microwave apparatus, either in cooking apparatus or in transmission stations.

Forensic Research Conclusions

From the twenty-eight above enumerated indications, the use of microwave apparatus is definitely not advisable; and, with the decision of the Soviet government in 1976, present scientific opinion in many countries concerning the use of such apparatus is clearly in evidence.

Due to the problem of random magnetic residulation and binding within the biological systems of the body (Category III:9), which can ultimately effect the neurological systems, primarily the brain and neuroplexuses (nerve centers), long term depolarization of tissue neuroelectric circuits can result. Because these effects can cause virtually irreversible damage to the neuroelectrical integrity of the various components of the nervous system (I. R. Luria, Novosibirsk 1975a), ingestion of microwaved foods is clearly contraindicated in all respects. Their magnetic residual effect can render the

pyschoneural receptor components of the brain more subject to influence psychologically by artificially induced microwave radio frequency fields from transmission stations and TV relay-networks.

The theoretical possibility of psycho telemetric influence (the capability of affecting human behavior by transmitted radio signals at controlled frequencies) has been suggested by Soviet neuropsychological investigations at uralyera and Novosibirsk (Luria and Perov, 1974a, 1975c, 1976a), which can cause involuntary subliminal psychological energy field compliance to operative microwave apparatus.

FORENSIC RESEARCH DOCUMENT

Prepared By: William P. Kopp

A. R. E. C. Research Operations

TO61-7R10/10-77F05

RELEASE PRIORITY: CLASS I ROO1a

Ten Reasons to Throw out your Microwave Oven

From the conclusions of the Swiss, Russian and German scientific clinical studies, we can no longer ignore the microwave oven sitting in our kitchens. Based on this research, we will conclude this article with the following:

Continually eating food processed from a microwave oven causes long term - permanent - brain damage by "shorting out" electrical impulses in the brain [de-polarizing or de-magnetizing the brain tissue].

The human body cannot metabolize [break down] the unknown by-products created in microwaved food.

Male and female hormone production is shut down and/or altered by continually eating microwaved foods.

The effects of microwaved food by-products are residual [long term, permanent] within the human body.

Minerals, vitamins, and nutrients of all microwaved food is reduced or altered so that the human body gets little or no benefit, or the human body absorbs altered compounds that cannot be broken down.

The minerals in vegetables are altered into cancerous free radicals when cooked in microwave ovens.

Microwaved foods cause stomach and intestinal cancerous growths [tumors]. This may explain the rapidly increased rate of colon cancer in America.

The prolonged eating of microwaved foods causes cancerous cells to increase in human blood.

Continual ingestion of microwaved food causes immune system deficiencies through lymph gland and blood serum alterations.

Eating microwaved food causes loss of memory, concentration, emotional instability, and a decrease of intelligence.