From: saj@chinet.chi.il.us (Stephen Jacobs)
Subject: Re: The *ACTUAL* dangers in microwaved food!
Summary: This I REALLY know about (no problem)
Organization: Chinet - Public Access UNIX
Distribution: na
Date: Tue, 25 Aug 1992 14:01:54 GMT

In article <23996@oasys.dt.navy.mil> kstuart@oasys.dt.navy.mil (Kenneth Stuart) writes:
>
>Now for the REAL danger!!  PLASTICS!
>
>Microwave popcorn has been flagged by health organizations as a possible
>carcinogen, but NOT BECAUSE OF THE MICROWAVE HEATING ITSELF!  In
>actuality, those neat little bags contain a metallized plastic disk
>which is heated by the microwave energy.  This heated disk melts the
>cooking shortening in the package, which in turn "fries" or roasts
>the popcorn and pops it.  (Remember the "THIS SIDE DOWN" notices on
>the packages??)
>
>When the oil is absorbed by the popcorn, this plasticized disk will
>usually overheat, and has been known to produce gaseous byproducts
>which can settle on the popcorn - which you then EAT!
>
>It's easy to find this disk.  Just look at the outside of the bag when
>you microwave your next bag of popcorn.  After cooking, you can usually
>see a well-defined scorched area of the bottom of the bag.  This is
>the location of the disk.  Rip the bag apart and take a look.
>
>This warning has appeared on bulletin boards in my local hospital -
>It is not originated by me!
>
>By the way, if you really like the convenience of microwaving popcorn,
>a lot of people simply put raw popcorn in a lunch bag and nuke it that
>way.  Completely safe (but you don't get the yummy taste of those
>saturated fats used for cooking - But that's why melted butter was
>invented...).
>
>Note also that boiling-hot coffee in styrofoam cups has also been
>flagged as a possible cancer risk for similar reasons.

I make my living working on things remarkably similar to what's discussed
above.  There was a major panic about this subject within the food industry
about 2-3 years ago.  The FDA made noises like they were ready to come in
with very strict regulations, and everybody had little lists of things they
wanted to analyze for at super-super low levels (you ever wanna find 0.03
ppb of benzene, come to me, for example).

Anyway, it turned out that there was very little there to worry about.  Some
kinds of paper (not plastic) turned out to release traces of benzene just as
they started to scorch, so people stopped using those kinds of paper.  Other
kinds of paper were found to release tiny traces of chloroform, but the levels
were too low to attract any real concern, and the process that caused this
was already going out of favor in the paper industry (remember that it was
only a decade or 2 ago that chloroform was a popular flavor in toothpaste
and mouthwash, with no obvious epidemiological signs of harm).  The stuff
that leached out of the plastics used for susceptors (that's the industry
word for the metallized plastic disks) was looked at every which way, and
nobody has found any difference between what leaches out hot and what leaches
out cold (say into soda in plastic bottles).  The main component is (funny
name alert) cyclic ethylene terephthalate trimer.  Again, there's a lot of
human exposure history here, and no epidemiological sign of harm.

FDA appears to have lost interest, because they had some very valuable staff
racing with the food industry on this, and there were no apparent threats to
the public showing up.  Basically, the issue just sits there.  The Center
for Science in the Public Interest moved on to other issues, again because
there didn't seem to be enough to support much excitement.  Food companies
routinely test for 'red flag' chemicals released when cooking packages
are overheated, now, so something came of it all.

The taste threshold for styrene in coffee is certainly less than 2 ppm (my
informed guess would be about 0.5 ppm).  If coffee in a styrofoam cup
doesn't taste like plastic, it contains less styrene than that.  Again,
there's a lot of human experience of exposure to low levels of styrene,
and no evidence of harm.  For what it's worth, levels of styrene have been
measured in hot beverages served in styrofoam cups, and have been indistin-
guishable from zero (you expect that from solubility, anyway, so no surprise).

There IS an unexpected hazard from hot tea with lemon in a styrofoam cup: the
oil droplets released by squeezing a lemon section can collapse the foam
structure of the cup, making holes in it and possibly letting hot tea dribble
into you.

Last: microwave heating is simply resistance heating (in the usual damp food
systems, anyway).  Has nothing to do with resonant excitation of water.

                                          Steve