Teflon frying pans are a wonder for flipping pancakes, but they become considerably less effective with time. This decay may be more than a culinary nuisance, scientists report in the 19 July issue of Nature: Teflon decomposes into a potentially harmful chemical that persists in the environment and may kill plants at high concentrations. So far, though, there's no evidence that the levels are harmful.
The chemical, called trifluoroacetate (TFA), occurs widely in the environment. Most of it results from the breakdown of compounds known as hydrochloroflurocarbons (HCFCs) and hydroflurocarbons (HFCs). But in many places, TFA levels in rainwater are too high to be explained by HCFCs and HFCs alone, a discrepancy that has puzzled researchers for almost a decade. University of Toronto chemist Scott Mabury and his colleagues undertook a systematic search for other possible culprits. Teflon and its relatives--which are used in many household and commercial settings--seemed like strong candidates because of their chemical composition and wide usage. But could teflon breakdown really produce TFA?
To find out, Mabury and co-workers characterized the compounds that are formed when pure teflon, as well as various teflon products, were heated. Experiments were conducted at a variety of temperatures up to 5001/4C to simulate both standard cooking and the burning of trash. They discovered that teflon decomposition not only produces TFA, but a suite of related molecules with unknown environmental effects. A computer simulation based on the data showed that teflon and HCFCs/HFCs together could account for the observed TFA concentrations in Toronto, suggesting that teflon was the hidden TFA source.
Although innocuous at its current levels, TFA can persist in the environment for centuries, which might allow it to reach concentrations that may harm plants, says Tim Wallington, an environmental scientist at the Ford Motor Co. in Dearborn, Michigan. But there's no cause for immediate alarm: "I don't think we should stop using teflon," he says. "I just think in hindsight we should have had better" environmental testing.