Heating Releases Cookware Chemicals

Science News ^ | 1-27-2007 | Janet Raloff

[blam]

Heating releases cookware chemicals

Janet Raloff

Nonstick coatings on fry pans and microwave-popcorn bags can, when heated, release traces of potentially toxic perfluorinated chemicals into the air and the food being cooked, a new study suggests. Although the chemicals aren't subject to any regulatory restriction and have uncertain toxicity, the researchers conducting the study suggest that people at least run kitchen-exhaust fans when using these products. A 2005 industry study found no such releases.

Chemist Kurunthachalam Kannan and his New York State government team, based in Albany, performed the tests on four brands of nonstick fry pans and two brands of microwave popcorn. Their findings appear online and in an upcoming Environmental Science & Technology.

The scientists heated new fry pans of various brands on a 250°C hot plate for 20 minutes. About half the samples released high amounts of gaseous fluorotelomer alcohols (SN: 10/11/03, p. 238: Available to subscribers at http://www.sciencenews.org/articles/20031011/note17.asp) and perfluorooctanoic acid (PFOA). The team heated two pans three more times to see if the chemical releases would fall as pans age. That occurred with one pan but not with the other.

The team also detected PFOA in water boiled for 10 minutes in two of the five pans tested.

When the researchers popped corn in the microwave bags, gaseous emissions contained low amounts of PFOA and high amounts of fluorotelomer alcohols. The oily coatings left inside the bags contained the chemicals as well, the team reports. The group didn't reveal the brands of nonstick pans or popcorn bags that it tested.

Cookware manufacturers have pledged to phase out PFOA, used to make some nonstick coatings, by 2015. The chemical is a suspected carcinogen, nervous system poison, and estrogen mimic found in the blood of people worldwide (SN: 3/25/06, p. 190: Available to subscribers at http://www.sciencenews.org/articles/20060325/note17.asp; 12/2/06, p. 366: Available to subscribers at http://www.sciencenews.org/articles/20061202/note16.asp).

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[Gabz]

Thank God for the Food Network, hopefully there will be a renaissance in the USA for cooking and eating healthy and delicious instead of what can be popped into the microwave for 5 minutes.

Bravo Sierra........my mother wasn't interested in cooking but I was cooking and cooking healthy 30 years before the Food Network existed. I watched it periodically for about a year or two, and can't be bothered with it. I've turned it on exactly twice in the past 4 years.

[Tailback]

Bravo Sierra

Well bully for you Mr. or Ms. old person. Some of us didn't take to cooking until our dearly departed elders left this earth. I'm glad to know that someone as talented, humble, and tolerant as you is still walking this earth. Since every close relative I know is now dead from cancer, I beg your forgiveness for having to learn to cook wherever I can.

[hoosierham]

Hey,I liked sassafras tea!

Some people just want to make everything bad for you.

I prefer glass and stainless storage and cookware but also have cast iron,aluminum,and plastic.

My mother used to use a metal scraper even with the non-stick skillets-I probably ate curls of Teflon with every egg or hamburger.(Might be a diet gimmick:lets the food slide through too quickly for fat to be absorbed!).

[niteowl77]

"I only use mine at temperatures high enough to scramble an egg. I have my trusty cast iron skillets for the hot stuff.'

I agree with you. I don't think one type of cookware does it all. I use my cast iron for the high temps. Stainless steel for other stuff. I use my enameled cast iron for chili. Can't beat chili simmered all day in that.

[NicknamedBob]

"The scientists heated new fry pans of various brands on a 250°C hot plate for 20 minutes."

That's not science. That's an engineering test to destruction.

A recent commercial for Pyrex spoke of putting the ovenware in a 300^oC oven. The narrator said, "It turns other saucepans into sauce!" They showed a metal saucepan melting and slumping in the heat.

My advice is, "Don't try cooking in a kiln, unless you're baking bricks."

And junk science is worse for your health than junk food is bad for your nutrition.

[grey_whiskers]

Nice story on Teflon. IIRC the discovery of Teflon was pretty much an accident too, involving some pressurized tanks of a some fluoridated gas which spontaneously polymerized (not "depolymerized).

Reminds me of a long ago story in Analytical Chemistry about a strong taste appearing sporadically in ready-made cake mixes which baffled the flavour chemists.

Apparently some of the test batches had used iodized salt, which ended up creating trace quantities of iodoform during the baking process.

The reason it was so hard to nail down was
a)not all of the batches had used iodized salt
b)not all of the iodized salt created iodoform
c)only about 25% of the population had a particular sensitivity to iodoform.

Oh, the things that make you wonder!

Cheers!

[RebelTex]

"All of mine are stainless steel with iron bases."

What brands and where to buy, please?  (Some for kitchen and some for camping.)

I've been looking for exactly that combo, but all I find are the Teflon and aluminum ones.

Thanks,
RT

[HiTech RedNeck]

Shouldn't there be some cooks' lore about this issue if so? It's practically universal to use salt in home baking, and the most convenient thing would usually be iodized table salt. I've been at many a potluck with homemade cakes and never heard anybody complain about them tasting weird.

[HiTech RedNeck]

A recent commercial for Pyrex spoke of putting the ovenware in a 300oC oven. The narrator said, "It turns other saucepans into sauce!" They showed a metal saucepan melting and slumping in the heat.

Saucepan made out of what, tin? Aluminum melts at 660 Celsius, and it would be glowing hot at that point.

[RebelTex]

"(Hint: think Ted Mack)"

"Round and round she goes, where she'll stop, nobody knows."

;^D

[flying Elvis]

Ditto. Nonstick for eggs, Le Creuset cast iron and copper-clad stainless for everything else.

[Let's Roll]

It smells like plastic - not all microwave popcorn but those with all the flavors added - butter etc. do.

It seems like not all people can smell it or they sure wouldn't eat that popcorn. It smells like a burning cigarette filter to me.

[flying Elvis]

You are correct about proper use. Most people I know ruin their teflon pans with nonstick sprays long before the coating ever wears off. As much as dislike the French, they produce some fine cast iron and copper pans.

[Myrddin]

That was quite a detective job. I recall the story about the tetrafluoroethylene gas polymerizing inside the cylinders. What an odd way to discover that it would polymerize into something so useful.

[NicknamedBob]

"Saucepan made out of what, tin?"

Quite possibly. I remember the visual, but I wasn't sure about the temperature stated. I tried Googling for confirmation, but couldn't find a reference.

Then again, "recent" for me could be any time in the last thirty years.

[Ditter]

I never thought about everyones sense of smell being different but you are right. That popcorn smell makes me want to puke! Some baked goods in places like Sam's Club bakeries have a disgusting sweet smell that also turns me off. Did you ever notice that?

[Let's Roll]

Haven't been to Sams in ages but the cigarette filter popcorn I'm talking about can just be the microwave kind that someone at work makes in the break room.

And we wonder why there are so many diseases particularly cancer.

[Eagle Eye]

You made the claim, you quantify and prove it.

As it is, you can't because there is no proof.

Trace amounts, especially those that are metabolized, are still meaningless.

[Robert A Cook PE]

250 degrees Celsius = 482 degrees F.

Stovetop: This is way above even cooking oil preparations (which would heat the whole pot), and much, much higher than ANY local (pot bottom) temperatures for normal cooking. Hence = It's NOT a realistic temperature any any cases other than the pot burning up.

Oven temperatures: Most cooking is between 400 and 450, it's possible 480 degrees can be reached. But, baking is lower temp, and Teflon cookware (handles, rivets, the Teflon itself) isn't used this way. AS most have pointed out in this thread, 482 degrees in a (dry, or empty) pot or pan is done by steel or ironware.

The PREMIS that widespread distribution of the waste chemical from Teflon (chemically-lined) stove top cookware is foolish: There are too few pots produced this way, of those pots and pans, too few burn up this way, and of those few that do burn inside a house, the worldwde spread of chemicals from those pots isn't the source of the chemicals.


The (false)

[NicknamedBob]

Agreed. My "pop-up timer" shot out of the bird when I saw 250^oC.