Download Microwave use newspaper article

Microwave use, good or bad?
With the recent increase in electricity tariffs my dad (who usually isn’t very stingy) packed away
the microwave with the excuse that it was going to consume too much electricity. Of course that
started a little war at home, and yes, I did win because of course I had a better case than he did
with respect to the convenience that we enjoyed with the microwave. Beyond issues of electricity
consumption (which some have argued is not a big problem because after factoring in how often
as well as how long one microwave cooks food, the cost is actually cheaper compared to the cost
of gas) are there other concerns of consumers about the use of microwaves that are indeed
grounded by fact? Answer is yes, there are concerns and no, not all the concerns are backed by
scientific evidence. One major concern that has been raised by consumers is the assertion that
microwave use can cause cancer. To better distinguish between the claims that are facts and
those that are fiction, it is important to understand what microwaves are and how they manage to
cook food so fast.
History of microwaves – what are microwaves and how its use in food processing?
Forgive the scientific mumbo jumbo but as I explained earlier it is important to understand some
of the physical principles backing microwave use so as to understand what effects they may or
may not have on us. So, here goes; microwaves are waves of oscillating electromagnetic energy
that are similar to radio waves but move back and forth at a much faster rate, described as “high
frequency radiowaves”. They appear between radio waves and infrared waves on the
electromagnetic (EM) spectrum. This region in the EM spectrum is 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). In nature microwaves
are given off by stars (including the sun). Microwaves are unionizing radiation, implying that
they are not radioactive neither can they cause other substances to become radioactive; they
only have the ability to vibrate fast enough to produce heat but do not disintegrate into ions.
Microwaves are selective, primarily affecting molecules which are electrically asymmetrical or
polar (in other words having both a positive and negative charge); like water. Microwaves
therefore heat food by causing the water molecules in it to resonate at very high frequencies (that
is energizing the water molecules to produce kinetic energy) which eventually turn to steam
which heats the food. Microwave-oven energy is more penetrating than heat that emanates from
a conventional oven/stove. It immediately reaches molecules about an inch or so below the
surface (radiation). In contrast, regular cooking heat, and using utensils and a stove, goes through
food rather slowly, moving inward from the outside by process of conduction.
Microwave technology is thought to have been originally developed by the Germans during the
Second World War as a radar system although it is believed that the idea behind its use in food
processing (the microwave oven) was accidentally stumbled upon in 1946 by Dr. Percy Spencer
who realized that a chocolate bar he had in his pocket while working with a radar unit had
melted. Among other things microwaves are currently used by fixed traffic speed cameras, and
for radar, which is used in burglar alarms, by aircraft, ships and weather forecasters as well as in
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mobile phones. In medicine microwaves are sometimes used in place of surgery eg in
hyperplasia of the prostate. In the kitchen they are used for cooking, heating thawing/defrosting.
Why do people prefer microwave cooking?
Microwave ovens have been in use for more than 50 years and it is reported that as many as 90%
of American homes own or use microwave ovens. Microwaves have become very useful kitchen
appliances for their convenience and the fact that they do not occupy a lot of space and so can be
used even in very small rooms that otherwise cannot take an oven.
Concerns with Microwave use; facts vrs fiction
As stated earlier, a number of concerns have been raised with microwave use, among which
include the claim that microwave energy destroys nutrients and causes cancer. Well, with regards
to nutrient retention, some nutrients break down when exposed to heat from all forms of cooking.
Most of the concerns are especially with cooking vegetables as cooking in addition to destroying
the structure of the nutrient through the heating can leach nutrients (e.g. vitamin C) into the
cooking water and this water if poured away makes these nutrients go waste.
Some studies have shown that the effect of using microwave energy to cook food is no more
detrimental than other conventional methods of cooking. An experiment conducted by d.l.Fuente published in 2002 for example showed that although calcium and phosphorus levels
reduced in milk heated with a microwave and a water bath, the amounts were not significantly
different in both treatments.
Interestingly, some other studies have shown that cooking with microwaves retain more vitamins
than other cooking methods because it uses less water and less time. In studies at Cornell
University, scientists looked at the effects of cooking on water-soluble vitamins in vegetables
and found that spinach retained nearly all its folate (folic acid) when cooked in a microwave but
lost about 77 percent when cooked on a stove. They also found that bacon cooked by microwave
had significantly lower levels of the cancer-causing chemicals known as nitrosamines (generated
especially during char-grilling of meat) than conventionally cooked bacon.
Another concern with microwave energy is the phenomenon termed “erupted water
phenomenon”. Because of the nature of microwaves, they can superheat water and other fluids
without boiling them. As a result of this water heated in a microwave can explode with agitation.
A genuine concern of this phenomenon is the danger of burns as there have been reports of
people being scalded in the face and hands. I have personally experienced burns from super
heated water and so can identify with this concern.
Yet another valid concern of microwave use is the fact that substances used in the manufacture
of the plastics used (known as plasticizers) may leak into food when it is wrapped in plastic or
placed in a plastic container and microwave heated. Fatty foods in particular, such as meats and
cheeses cause a chemical called diethylhexyl adipate to leach out of the plastic. The effects of
these chemicals have been extensively studied in animals but not in humans and there have been
findings that these substances have the ability to cause cancer in animals. Based on these studies,
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there is therefore a limit to the amount of leakage allowed by the FDA in a plastic bowl and the
maximum allowable amount is 100–1,000 times less per pound of body weight (in humans) than
the amount shown to harm laboratory animals over a lifetime of use. There are therefore strict
guidelines for the manufacture of plastics for use in microwave ovens.
In 1992, researchers at Stanford University Medical Center found that warming breast milk in a
microwave destroyed the antibodies that provide passive immunity to infants, and destroyed 96%
of liposome activity that inhibits bacterial growth and this has generated a scare that microwave
use is detrimental for infants. The destruction of some (but not all) of these nutritive factors were
observed even at a low setting. The limitation of this study was that the microwave heated breast
milk was compared to unheated breast milk only and not breast milk heated by other
conventional methods
The fact based on research is that heating breast milk well above body temperature regardless of
whatever cooking method is unsafe for use and so these changes that were observed were due to
the fact that the breast milk was heated to begin with and not the microwave energy used for the
heating per se. The real concern with microwave use in Baby food is the fact that baby’s food
may also be superheated without container appearing hot. This can cause burns if food is given
directly to baby without allowing cooling. There may also be concerns with baby bottles not
being microwave safe and so leaching out chemicals into baby’s food. There is no evidence
currently to support claims of diseases in children whose feeds are microwave heated.
An alleged experiment by a secondary school student known as Arielle Reynolds in Sussex
demonstrated that one plant watered with microwave heated water failed to thrive compared to
another that was heated by a stove and this has also been the basis on which many antimicrowave advocators describe microwaves as hazards as they cause heated molecules to “lose
their vital energy”. The “Experiment” has since not been replicated in a more controlled trial.
Microwave use and disease
There is evidence based on animal experiments to support that direct exposure to microwaves
can induce oxidative stress and cognitive impairment. Human based studies on the effects of
eating food prepared in a microwave are limited well except for an alleged human study,
“Comparative Study of Food Prepared Conventionally and in the Microwave Oven” reported to
have been published by Raum & Zelt in 1992. It is reported that a scientist named Dr. Hertel
with a group of 7 other volunteers locked themselves up in a hotel room to conduct this
experiment, subjecting themselves to microwave heated food for a period of time and then
testing their blood afterwards. These scientists never supplied the data to support their claims but
unfortunately their work is being sited time and time again to support statements that microwave
cooked food causes cancer and sterility.
It must be stated categorically that microwave heated food does not become radioactive and so
the food in itself is not harmful. Covering food when microwave heating therefore does not
“prevent” food from getting radioactive as supposed by some advocates but only serves the
purpose of preventing splatter in your microwave oven. Direct exposure to high doses of
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microwaves (and not microwave heated food) may pose health risks because if of course they
have the ability to cook food then they could “cook” us as well. The American food and drugs
authority (FDA) has safety guidelines for the amount of microwaves that can leak from a
microwave oven. Microwave ovens are therefore designed to stop producing radiation once the
door is opened. On the basis of current knowledge about microwave radiation, the FDA believes
that ovens that meet its standard and are used according to the manufacturer's instructions are
safe for use.
Are we to throw our microwaves away?
There is currently very little evidence that microwaving food or water causes any ill effects both
in the short and long term. The claims that exist are presented in pseudoscientific language (not
from any valid peer-reviewed research) and so make it difficult to generalize. It is however
always better to be safe than sorry and YOU can make microwave cooking more “safe”.
First of all, purchase microwave ovens made by reputable manufacturers and follow the
manufacturer's instruction manual for recommended operating procedures and safety
precautions. Use only plastic containers labeled “microwave safe” for microwave cooking. Do
not use containers with metallic decoration or aluminum foil for microwave cooking as these can
reflect microwaves and generate sparks. Plastic storage bags, plastic grocery bags and foam trays
are also not advised. Brown paper bags are also not advised because they are usually
manufactured from recycled paper which also contains unsafe chemicals. Do not reuse
containers that came with microwave convenience foods or take-away because they might be
designed for one-time use only. Always look out for the re-use sign on plastic containers. The
most ideal containers for microwave use are glass and ceramic dishes, Paper plates, towels, and
napkins, wax and parchment paper. Do not over-heat water or liquids as these can cause
accidents.
As there is very little evidence to at least test the claims of anti-microwave advocates, I would
like to task Ghanaian research scientists (including myself) to be interested in and conduct
studies in this field to supply evidence and more conclusive information. In the mean time
consumers should take personal responsibility of their health and follow appropriate practices for
microwave use.
Ayande Ruthfirst Eva and Frank Hayford
Department of Dietetics,
School of Allied Health Sciences
College of Health Sciences
Korle-Bu.
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