Persistent Organic Pollutants: Environmental Stain Fading Fast

Shocked that chemical offshoots of his company's products were winding up in polar bears and seals, the CEO of 3M put an end to the existing version of Scotchgard® in 2000. Business observers were struck by how quickly this multinational corporation removed a flagship commodity worth hundreds of millions of dollars from the market. Now some scientific observers are becoming impressed by how quickly the degradation products that prompted this move appear to be disappearing from the environment. University of Toronto chemist Scott Mabury has been among those identifying a decline in the presence of agents such as perfluorooctane sul-fonate (PFOS), one of a class of manufactured chemicals that feature chains of carbon atoms bonded to fluorine atoms. In an Environmental Science & Technology paper published online 30 November 2006, Mabury and colleagues report a significant drop in PFOS levels in Arctic ringed seals over the last two years to about a third of what they were in 2000, along with ongoing declines in levels of related fluorine-based compounds. Mabury notes that change has followed hard on the heels of 3M's withdrawal of its old version of Scotchgard, which consisted of precursors to PFOS and other perfluorinated carboxylic acids, part of a class of perfluorinated chemicals (PFCs). PFCs have come under fire since their ubiquity and persistence were confirmed in the late 1990s, although their toxicological potential as carcinogens and hormone disruptors is still being investigated. PFOS and its cousin perfluorooc-tanoic acid (PFOA) have been found in blood samples from humans living all over the world and animals in Arctic, temperate , and tropical regions. For several decades, PFCs had found widespread use in applications such as nonstick coatings for metal and paper surfaces , as well as stain and water repellants on textiles and carpeting. After its accidental discovery in the early 1950s, Scotch-gard became one of the best known and most popular of these products, appealing to consumers who wanted to keep wine stains off their upholstery and an even more substantial industrial client base with highly technical goals, such as optimizing the performance of microchips. John Giesy, now the holder of a Canada Research Chair in Environmental Toxicology at the University of Saskat-chewan and the researcher who first reported PFCs in the environment, was with Michigan State University in 1997 when 3M asked him to offer opinions on the state of the knowledge of compounds produced by …