Advice about Microwaving
Berkeley Parents Network >
Advice about Microwaving
I know some people don't like to use microwaves, but I'm not
entirely sure why that is. Does anyone have any concrete
evidence of microwave dangers? I mean, does it really do
anything bad to the food?
This was sent around on the Web:
Dr. Edward Fujimoto, manager of the Wellness Program at Castle
Hospital, was on TV talking about dioxins and how bad they are
for us. He said that we should not be heating fatty foods in
the microwave using plastic containers. He said that the
combination of fat, high heat and plastics releases dioxin
into the food and ultimately into the cells of the body. Dioxin
are carcinogens and highly toxic. Instead, he recommends using
glass, Corning Ware, or ceramic containers for heating food.
So such things as TV dinners, instant ramen and soups, etc.,
should be removed from the container and heated in something
else. Paper isn't bad but you don't know what is in the paper.
To add to this: saran wrap placed over foods as they are
nuked, with the high heat, actually drips poisonous toxins
into the food. Don't freeze your plastic water bottles with
water as this also releases dioxin in the plastic.
I received yesterday a mail from a friend warning about the
dangers of microwaving food in a plastic container: the process
would release carcinogenic substances in the food!
Being my paranoid self I made my soup-in-a-bowl lunch in a
ceramic plate instead of the provided plastic container, and last
night when my son wanted to defrost meat that was in a foam
receptacle I told him to use a glassware instead. It would be
interesting to find out if there are any solid evidence to this!
This is a well-known urban legend, based on a small amount of
facts. See: http://tafkac.org/ulz/plastic.html
That site also lists what the USDA says to do, which can
basically be summed up to: Only use cookware that is specially
manufactured for use in the microwave oven. These can be glass,
ceramic, paper, and plastics as long as they're labeled for
microwave oven use. These are all tested and rated to safely
endure the heat of foods being cooked in/on them from a
microwave. Other items may not be and can actually start to
melt, which is when stuff in the plastics could become mixed with
Please note that the thing about dioxins leaching into plastic from
microwave use appears on my favorite web page for checking out urban
legends -- snopes.com, as basically false, at least in the form it
appeared in several of the posts in the last advice column. Check out
I make it a policy, anytime I hear anything alarmist like this,
ESPECIALLY in the form ''I heard it in an email from a friend...'', to check
it out on snopes before passing it on.
Snopes has a full account of this story - although I would be
careful about what kinds of plastics you use in the microwave,
the information being sent around via email is not founded in
any real studies: http://www.snopes.com/toxins/plastic.htm
By the way - Snopes is an excellent resource for testing the
veracity of urban legends. I'd suggest ALWAYS checking before
mass-forwarding email pronouncements that you receive.
Um, that e-mail about plastics dripping toxins into our food in
the microwave -- that's been largely discredited by the
American Cancer Society. See
http://www.snopes.com/toxins/plastic.htm. We should really try
not to believe every piece of e-mail we receive.
I'd heard this then heard it was a hoax. You can check out the full skinny at
snopes.com (almost always good for this sort of rumor mill stuff, like the
deodorant/cancer ''link''). Interesting reading.
The bit about microwaving food in plastic container is false - http://
www.snopes.com/toxins/plastic.htm (actually snopes.com is really good for
checking any kind of info like that... although pretty much as a rule I would not
believe 99% of information that comes through an email forward.)
just the facts!
I Googled this topic and found several urban legend/rumor type
sites partly debunking this message; see
which links to the Dept. of Agriculture guidelines on
The dioxins thing isn't a hoax but - well, judge for yourself...
Do not believe these stories. I am an anlytical chemist and
specialize in analyzing food packaging materials and their
migration or lack of into foods. I have extensive experince in
the testing of all manners of food packaging materials and can
guarantee that no dioxins or other poisonous toxins are present
in the food packaging materials and cannot be released or dripped
into the food. Brad
Claim: Research shows that microwaving foods in plastic
containers releases cancer-causing agents into the foods.
See http://www.snopes.com/toxins/plastic.htm for full text.
Origins: This ''health alert'' began appearing in people's inboxes in
February 2002; It's a pretty good assumption that if using plastic containers
in microwaves — as millions of people have been doing for decades —
posed a significant risk of cancer, you'd be hearing about it somewhere other
than an e-mail forward.
Is there really something to the central claim of this e-mail, that heating
plastic in microwaves releases a cancer-causing agent into the food? It's
within the realm of possibility, but it must be stressed the FDA does impose
stringent regulations on plastics meant for microwaving. Also, if there are
dioxins lurking in the plastic containers we heat food in and the process of
warming those receptacles looses those nasties into our ingestibles, we've yet
to locate the studies that prove this. However, because most dioxins are
dangerous compounds we want to have as little to do with as possible, many
people are cautious about using anything associated with them. So, if you're
one of the concerned, be sure that when you cover a dish you intend to
microwave with ordinary plastic wrap you do not let the covering touch the
food, because some of the plasticizer in the wrap — which may contain toxic
chemicals, as opposed to does contain toxic chemicals — could migrate to
what you're cooking, especially foods high in fat. Alternatively, use waxed
paper for this purpose. Those who are very, very cautious about the potential
for dioxin contamination might choose to adopt the central point of the
e-mail's advice, which is to decant all items into glass or ceramic containers
But how real is this concern? According to Dr. George Pauli, a leading Food
and Drug Administration scientist, not very. He acknowledged that some
plasticizers do migrate into foods, particularly those containing a lot of
fat, oil, or sugars. But research has found no ill effects from consumption of
plasticizers in FDA-approved plastic wraps or from freezing or re-using
plastic water bottles. Even so, others remain unconvinced, and those on both
sides of the issue recommend not letting plastic wrap touch food during
In the few posts I read in response to this question, posters
referred to information they received via email or on the web
about the possible dangers of microwaving food in plastic
containers and using saran wrap in the microwave, etc.
So many of these emails that get passed around are made up and
an excellent site to look at before you pass these emails or the
information in them on to anyone is www.truthorfiction.com.
They research these e-rumours and publish what they find out.
Here is a link to their report on the email about microwaves and
plastic. They found it to be ''unproven & fiction'' but interested
folks should read the report itself as you may consider it
more ''disputed'' than ''fiction'' and the report also provides
links to where to find more accurate information on this issue:
Truthorfiction.com is also a great site to look up any
other ''urgent,'' ''important,'' or other mass emails that you
Does anyone have any information on heating up frozen cubes of
baby food in the microwave? Is there a problem with killing the
nutrients in the organic food that I prepare? I usually use the
defrost level three for two minutes. Any advice would be
The nutrients in any kind of food are sometimes changed by cooking and
preparing... check out the book Super Baby Food by Ruth Yaron. It's all
about making, freezing and serving homemade baby food. There is some
information there about microwave usage for this.
I also make and serve organic, frozen baby food to my son. I do not have a
microwave, so we get the next day's food out of the freezer the night before
and it thaws overnight in the fridge. Then we put the containers in a hot
water bath for about ten minutes prior to feeding time. This works great!
Freezing food and then defrosting it with a microwave will ensure the food
loses a lot of its vitality. Freshly cooked food would be better and can be
stored in a sealed container in a refrigerator for about 3 days. Microwaves
are not advisable for heating or cooking any food.
I don't know about killing the nutrients but I microwave the cubes of
babyfood all of the time. I put the cubes in a bowl and set the microwave
for between 30 and 45 sec. I stir and then put back in for another 15 or so
depending on the number of cubes and what type of food it is. I can't wait
to see other people's responses.
Is it OK to use the microwave to warm up my baby's bottle? I have heard conflicting information as to whether
the only risk is hotspots, which can be managed by diligent shaking, or whether the microwave actually changes
the nutritional value of the formula or breast milk. Thanks for any info.
I've always been told that microwaving formula and/or breastmilk is a bigno-no. I believe it breaks down the
composition of the milks. But I learned a trick from the neonatal intensive care unit for heating up milk:
Microwave a cup of water for 1-1/2 minutes. (The hospital used foam coffee cops; I used coffee mugs.) Then
put the bottle of formula or breastmilk in the hot water for about 30 seconds.
Microwaving breatmilk is a HUGE no-no. There are living anti-bodies in breastmilk, and they die in the
microwaving. Though you can always micro-wave water, and use that hot water to thaw frozen milk, or warm
cold milk. There are fairly inexpensive bottlewarmers that you can buy too. I heard about someone taking her
frozen bags of milk, and using the coffee maker to thaw it. I'm not exactly sure what she did though.
Microwaving formula, as I understand it, you only risk hot-spots. Though if you're worried about it, just heat the
water, and add the formula to that. The hot water helps disolve the formula better anyway!
To be safe, I used to microwave the water (eg. in a big mug) before adding it to the baby's bottle with the
formula powder. But, if your baby's like mine, you may find that s/he doesn't really care whether the formula's
heated or not!
- Mom of a 6-mo. old
Here's what has worked for us:
Breast milk: to heat this up we microwaved half a mug of water for about 45 seconds. We set the bottle in the
mug of warm water and the breast milk was warmed up in about 3 minutes. It worked well for us to get the
bottle started then change baby's diaper. By the time our routine was finished, the milk was warmed.
Formula: We microwave the bottle with 4-6 oz. of cooled boiled water for 10-15 secs. and add formula after
that. We don't put the nipple in the microwave and have never experienced any hot spots on the bottle (and
Also, another suggestion: Someone gave us an Avent Bottle Warmer. It plugs in, warms the water very quickly
and you can set the bottle (formula or breast milk) in to warm up. It takes a little longer than the suggestions
above but, the advantage about this is that it comes with a bowl that sitson top of the steamer (obviously not at
the same time a bottle is warming). You can put baby food in the bowl and it will warm it up but it takes 10-15
mins. to heat a jar of food that
My son has been on formula since birth. What I do when I make his bottle is microwave the water in the bottle
before I add the formula, when making a single bottle. But when you want to make a few bottles ahead of time,
just shake them up and remove the nipple before microwaving. I have also asked around about whether or not
the nutrition level is lowered after microwaving bottles and the only warning I have heard is that hot spots in the
bottle can form. I personally have never had that problem just do not microwave the bottle more than 15 to 20
seconds on high. My son is 20lbs now and perfectly healthy. Good luck!
I'm replying because someone just wrote that she ''couldn't wait'' to see responses to her post! I also
microwave frozen cubes for my 1 year old boy. I'm a very lazy cook, and while I like to get as much nourishing
food as possible for my baby, I HATE the process of cooking it and preparing it into baby food edibles. I really
am much less likely to do it if it means 3X daily [or more!]. So we do a bunch ahead of time, freeze it, then
microwave it for 20-30 seconds to get it mildly warm. Mmmm, organic veggies come pre-chopped in bags!
Whole Foods has frozen organic sweet potato cubes! Soy nuggets, boca burgers, home-made soups! He loves
them all, and I'm actually feeding him healthy foods, which, believe me, I'm much less likely to be vigilant about
if it means lots of extra time at the stove. Which, by the way, means less time with him on the floor.
I found the microwave discussion interesting. I did a Google search and found a site called ''How Things
Work,'' by a physics professor, Louis A. Bloomfield, at the University of Virginia
http://rabi.phys.virginia.edu/HTW/microwave_ovens.html. It is done in question and answer form, and he will
answer your questions. He explains how microwaves work, addresses the perceived dangers of microwaves,
and discusses whether microwaves have an affect on the nutritional value in food. His answer,'' No more so
than conventional heating does. Overheating some nutrients can damage them, so that microwave cooking does
affect food's nutritional value. But microwave cooking is far less likely to cause serious molecular damage to
food than flame broiling or frying.''
I hope this helps.
I've heard that microwaving food in plastic containers is somehow harmful,
don't have any more information than that. Does anybody have any information
they can share? Is it a particular type of plastic? Does it matter what
food? What about baby bottles? Thanks
An alternative to using plastic wrap in the microwaves is to
cover your food with a wet paper towel. Wax paper would work
also but doesn't cling as well.
Putting plastic in the microwave is bad for the air. Some people
say that you shouldn't even have plastic in the house. Plastics
release volatile organic compounds. The more flexible it is, the
worse it is. For instance, the plastic they wrap around meat is
probably one of the worst. The hard plastic that encases your tv
is probably one of the best. This website has information on
indoor air pollution and putting plastics in the microwave:
You can get thousands of web pages by typing ''sick building
syndrome'' ''environmental illness'' ''multiple chemical
sensitivity'' or ''indoor air pollution'' into a search engine.
Some are personal web pages. Some is research done by NASA or
the EPA. There is plenty of information out there for people who
want to improve their health. Indoor air pollution can cause
cancer many years down the line. But it can also affect almost
any body system immediately: skin, lungs, digestion, central
nervous system, emotions, etc.
I asked your question to Paul Goettlich of
www.mindfully.org, and got an extensive list of studies
mostly having to do with plastic itself leaching into the food it
holds. He did have some studies about microwaving
plastics that will answer your question. Here's what he sent
Plastics for microwaving can be made of various types of
polymers. Food wrap is generally made from PVC,
especially the commercial brands that come in large sizes
from food supply companies. Consumer brands are also
made of PVC, but some are being made of other types.
When reading the files below, please understand that the
literature on the toxicity of plastics is not only limited, but the
bulk of it does not take into account the extremely low
concentrations that have an effect on the endocrine system.
Nor do they account for the synergy that can occur between
any number of chemicals/polymers. Additionally, each
person is unique and in their own unique environment.
Here are a few file for you to read:
How Plastics Are Made
Microwave enhances overall migration from PVC to foods
Packag. Technol. Sci. 12, 277-281.
Polyethylene Terephthalate Migration and Toxicity
Evaluation of plastics for food packaging Food Additives and
v.11, n.2, 221-230 1994
Detecting Nonylphenol in PVC Food Wrap
Japan Offspring Fund (JOF) Monthly Newsletter n.117 & 118
Plastic food wrap poses threat to environment: Dioxin
TADASHI MATSUI & YOMIURI SHIMBUN / The Daily Yomiuri
Does Plastic in Microwave Pose Health Problems?
Wall Street Journal 12oct98
mindfully.org is a great site for finding out information on
plastics and other toxic things in our environment. Every
time I go to this site and read something, I look around and
realize how much plastic is in my own home. Then I go to
the store and realize how few alternatives we have to it
these days. Check it out!
I read a study somewhere done by a teenager about the
use of plastic in microwaves and its dangers. Her findings
were widely accepted. She found that the fat in the food that
is microwaved causes a chemical reaction with the plastic
container that is not healthy. The recommendation was to to
put the food to be microwaved in a glass container. The
less the fat in the product the lesser the chemical
breakdown withthe plastic.
I'm so glad you asked about this! It's something I feel very
My understanding about plastics is that certain kinds of
plastics can essentially off-gas chemicals into the foods
that are stored in them. Some of these chemicals are
carcinogenic, and some of them are what are called
''Endocrine Disrupting Chemicals'' (EDCs), which cause
reproductive system harm. This means that many of the
compounds (from what I understand) can emulate
oestregens, and that causes, well...this is what an article in
the Green Guide says:
''...scientists hypothesize that endocrine-disrupting
(hormone-altering) chemicals that we encounter in our
everyday lives, such as in the food we eat, may be
responsible for the dramatic decline in sperm counts and
increasing rates of breast, testicular and prostate cancers,
endometriosis, and some birth abnormalities, such as
undescended testicles. In wildlife, endocrine disrupting
chemicals have been linked to abnormal reproductive
organs in Florida alligators and compromised immune
systems in dolphins.''
Here are some tips:
- Plastic wrap should never come in contact with fatty food in
the microwave. It is also important not to use left-over
margarine or yogurt tubs in the microwave. Use ceramic or
glass cookware instead.
- Avoid food, water and beverages sold in cans, plastic
containers and bottles, when possible. Try to buy water from
distributors who can deliver large glass jugs in convenient
- As a precaution, you can unwrap prepackaged foods and
store them in nontoxic glass, ceramic or steel bowls, or
Ziploc bags (made of LDPE).
- In general, heat promotes leaching.
Mothers and Others (also in the Green Guide) have a great
guide about food storage containers, which I've included:
Plastic used for containers can be identified by their
recycling codes, as listed below. Most wraps on
pre-packaged foods lack identifying symbols [so assume
they are not good for the microwave]:
1. Polyethylene Terephthalate (PETE or PET): No known
2. High Density Polyethylene (HDPE): No known hazards.
3. Polyvinyl Chloride (PVC or vinyl): Plasticizers are added to
many PVC products to make them flexible. These include
phthalates -- suspected endocrine-disrupting chemicals
(EDCs), DEHA, another possible EDC, was found to leach
from PVC cling wraps into cheese. Grocery stores
commonly use PVC to wrap deli meats and cheeses.
Reynolds cling wrap is PVC. Some waters and vegetable
oils are bottled in PVC. Ad PVC's manufacture and
incineration produces highly toxic dioxins, as does the
PVDC used in Saran Wrap, according to Consumers Union.
4. Low Density Polyethylene (LDPE): No known hazards.
5. Polypropylene (PP): No known hazards.
6. Polystyrene (PS or Styrofoam): Made from styrene, a
suspected carcinogen, PS also contains p-nonylphenol;
both chemicals are suspected EDCs. Do not consumer fatty
foods or alcoholic beverages from Styrofoam containers;
styrene can leach into these substances. Some opaque
plastic cutlery is PS, as well.
7. Other Resins, including Polycarbonate (PC): Most clear
plastic baby bottles and 5-gallon water bottles are made of
PC. Bisphenol-A EDC is in PC, and has been found in water
and heated infant formulas bottles in PC, as well as food
cans lined with a plastic film.
I got this from ''The Green Guide'' newsletter, which is a
really great source for ''practical everyday actions benefiting
environmental and personal health''. I have found more
excellent information from them about pesticides, drugs,
and so on than anywhere else. If you are interested in
subscribing (which I recommend for any parent), they are at:
In the same vein as the 'plastic and microwaves' subject (see below)
anyone know if the avent bottle system has PVCs? Are avent
bottles safe for microwaving milk/soy milk/formula in? I have
been unsuccessful at locating any info on these bottles both on
the web and Consumer Reports.
I did a great deal of research on Avent bottles in 2000 and
found very little information. In the end, I was left with the
conclusion that the verdict is still out on microwaving ANY
plastics and I thus got into the habit of microwaving a Pyrex
glass measuring cup of water and plopping my bottle in it for a
few minutes. It takes just a few minutes longer than
microwaving the bottle itself, but I figured it was safe and
would also avoid any ''hot spots'' that would occur by microwaving
the milk directly.
On the same note, I found some cute little glass Pyrex dishes at
Safeway and I use them everyday to microwave food (instead of
plastic refrigerator containers).
Good luck with your decision.
Mom of two
I don't know about PVC in the plastic, but I used to microwave
water in the Avent bottle, then add formula. They are
advertised as microwave safe, - but another issue came up. The
plastic would expand, making it near impossible to screw the
nipples so they popped in just right. This meant a lot of leaks
would occur. When the plastic is cool, it was easy to screw the
nipple in right even if the formula was hot. Just something to
consider if you need to place nipple on right after microwaving.
Avent bottles contain Bisphenol-A, an endocrine disrupting
chemical. (If you want to know why those are to be avoided,
read Our Stolen Future or check out the website
http://www.ourstolenfuture.com.) I would recommend
switching to glass bottles, and -- if you have to use plastic --
using bottles that are not clear plastic, like the Avent ones.
But, hey, you asked about microwaving. Heating plastics
increases the amount of leaching that occurs, so I would
definitely avoid it.
The instructions with Avent bottles indicate that the bottle
(but not the nipples, spouts, etc.) are safe in the microwave.
Avent bottles are polycarbonate. Their liners are polyethylene.
Search ConsumerReports.com for ''bisphenol'' and you'll find the
relevant articles to baby bottle safety. The plastics industry
and FDA refute Consumer Report's allegations though:
PVC, otherwise known as vinyl, is softened with plasticizers
that leech out over time (vinyl gets brittle). It's
carcinogenic, etc. It's mostly used in teether toys and
Polycarbonate, when heated, supposedly leeches bisphenol-A,
which acts like estrogen hormone and disrupts glands.
Elsewhere, I've heard that microwaves drive minute plastic
particles into food as well as potentially alters the
chemistry/nutrition of food.
I'm practical rather than paranoid: I err on the side of
caution if I can afford to. I microwave food in glass, then
transfer it to the serving container, use Glad Cling Wrap
(polyethelene) instead of Saran, etc.
Here's my non-polycarbonate, non-microwave solution:
I keep a large vacuum-insulated bottle which I fill up every
morning with boiling water. When I need to warm a baby
bottle, I dispense hot water into my 32 oz tumbler and
dunk my Avent liner bottle into it. It's ready to serve in
i believe avent bottles are polycarbonate, not pvc, but also
these are not good for kids.
medela, evenflo colored and opaque (not clear), and
gerber (colored) are all made out of #5 for recycling (PP), which
is ok. they might have changed, i have an old list from
''mothers and others'' which might be outdated now (their web
site is gone for some reason). in recycling code, apparently
you want to avoid not only #3 (pvc) but also #6 (PS) and
#7 (polycarbonate). often you have to call the manufacturer
and they can tell you (not always, someone from lamaze told
me that their toy was safe, after days of trying to get info,
''because it is made of plastic'')....
and maybe mothers and others are more cautious than you want to
I would urge you not to microwave any bottle filled with
breastmilk or formula. The liquid can heat unevenly, and high
heat can destroy nutrients. And microwaves are unpredictable.
It's too easy to heat milk too high and burn baby's tongue. But
you can use a microwave for quick heating; just don't put the
bottle in it. This is a trick I learned from the nurses in the
the neonatal intensive care unit. What you do is put your bottle
into water that has been nuked.
The hospital used a Styrofoam cup; I used a coffee mug at home.
Fill the cup about a quarter to a half full of water (you don't
want it completely full, or it will spill when you put the baby
bottle in it). Zap it for one minute on high. Then put your
bottle filled with breastmilk or formula in the water and leave
it in for about a minute. At the one-minute mark, refrigerated
breastmilk or formula will be at about room temperature. Leave
it in a bit longer for a warmer bottle.
A good while back I saw a TV investigative program addressing
just the plastics issue and I researched it a little more on the
internet, with little success. It is basically the same thing
about most plastics. The ones that were more harmful--according
to the program--because they released small amount of some
cancer causing chemical, which in the case of baby bottles would
basically build up over time in the body, as the baby ingesting
the liquid. I don't recall all the specifics of it, but
essentially they said that the hard, clear plastics bottles were
the ones that released the chemical and that the more pliable,
colored bottles (like the tinted ones from Gerber) are safer. I
emailed the Avent people requesting an explanation on these
findings and they said that they were not aware that their
bottles posed any risk whatsoever, and that their bottles are
safe, despite the presence of PVC in the plastics of their
bottles. In fact if you check on their website they actually say
that their bottles are made with PVC. I simply refused to
believe them and decided to go with the other bottles as well as
not using them in the microwave. As a precaution though I
suggest you not microwave any plastics in the microwave. It's
better to side on caution than take unnecessary risks,
especially when it involved your child.
Hi. I have an Avent. I was told never to microwave it. I know
that microwaving will destroy the properties in breast milk. I'm
not sure if that is the only reason not to microwave, or if it
is bc of the plastic.
Burned popcorn smell in microwave
We recently burned (*SERIOUSLY* burned)a bag of microwave
popcorn in our microwave, and can't get the smell (or yellow
color) to go away. We've tried various cleaning supplies, baking
soda, leaving it open for long stretches, etc. (and we've
checked the website for ideas). Nothing seems to work - and
after all of our efforts, the smell is still pretty strong when
we open the door. Anyone have any ideas??
A couple of years back, we had a turkey spoil (very seriously) in
our freezer while we were gone on vacation -- and had a similar
problem with a smell we couldn't get rid of. The solution --
recommended by Amana -- that finally reduced the smell to
tolerable levels, such that baking soda eventually cleared it up,
was to pack the refrigerator/freezer full of crumpled newspaper
and charcoal briquets, shut it up, and leave it for a few days.
Sounds weird, but was remarkably effective. I wonder if something
similar might work for you?
Sorry to say that the only thing that works is time. We had a
situation much like yours, and it took months to get rid of the
smell and yellow coloring. We kept finding the coloring in
various places, like under the sink where the popcorn bag
had been tossed into the garbage.
Now I use my air popper.
this page was last updated: Feb 3, 2013
BPN is now a 501(c)(3) non-profit and we are transitioning to a new website during
The opinions and statements expressed on this website
are those of parents who subscribe to the
Berkeley Parents Network.
Disclaimer & Usage for
information about using content on this website.
Copyright © 1996-2015 Berkeley Parents Network