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NON-STICK frying pans may be polluting towns and cities with a chemical that
is almost impossible to destroy naturally.

Canadian scientists have found that materials used to coat pans, such as
Teflon, degrade when heated into trifluoroacetic acid (TFA), an extremely
persistent compound that stays in the environment. 鈥淎ll of the 鈥榙irty dozen鈥� are
relatively non-persistent compared to this,鈥� says Scott Mabury of the University
of Toronto, referring to the United Nations鈥� top 12 blacklisted chemicals.
Surgical needles and engine additives are also made with fluorinated polymers
such as Teflon and Kel-F.

Until now, scientists have blamed TFA on hydrochlorofluorocarbons (HCFCs),
the gases that replaced the ozone-destroying chlorofluorocarbons. But rainwater
in big cities like Toronto contains far higher levels of TFA than can be
explained by HCFCs alone.

Mabury and his colleagues wondered if fluorinated polymers might be a crucial
contributor. They tested a range of fluoropolymers that are all heated in the
course of normal use. The researchers collected and analysed the gases released
when the materials were heated and found that one of these breakdown products
could combine with gases in the troposphere to form TFA.

Environmental models confirmed that fluorinated polymers are the likely
culprit. The predicted amounts of TFA produced by pans and other products
corresponded almost exactly with levels found in the Toronto rain. 鈥淲e believe
it鈥檚 a significant portion of the missing TFA in the environment,鈥� says Mabury.
TFA is only mildly toxic to plants and is not known to be harmful to humans.