Heating releases cookware chemicals.

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[degrees]C hot plate for 20 minutes. About half the samples released high amounts of gaseous fluorotelomer alcohols (SN: 10/11/03, p. 238) 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; 12/2/06, p. 366).