Interview Aerosols complicate PFOA picture
JUPITERIMAGES
concentration were published by Xiaodong Ju at Dalian University of Technology in China (Environ. Sci. A largely discounted wrinkle in PFOA should stay airborne long Technol. 2008, 42 [10], 3538–3542). the chemistry of perfluorooctanoenough to travel great distances. Ellis concludes that the PFO– likely ic acid (PFOA) indicates that this The collaborators used an ulis further concentrated in the sea ubiquitous chemical moves into trasonic aerosol generator to crespray aerosols that, once airborne, the air more readily than previate a fine aerosol mist in a sealed should release some PFOA into the ously thought, according to new vessel. In a series of experiments atmosphere. research in ES&T (pp 3969–3974). funded by DuPont, they spiked deAerosolization is a potentially Experts say that the findings could ionized water and samples from important route of loss of PFOA have implications for PFOA’s fate in a river, a lake, and the ocean with from aquatic systems, says Envithe environment, but they ronment Canada chemist caution against extrapolatDerek Muir. “This process ing these laboratory results may help explain the global to the real world without distribution of PFOA and field-based verification. other perfluorocarbons, bePFOA is the best known cause the results of this lab of the perfluoroalkyl carstudy suggest that PFOA boxylates. A U.S. EPA will be transported in the Science Advisory Board adgas phase and also continuvised the agency in 2006 to ously exchanged between classify it as a likely human water and the atmosphere carcinogen. Animal studvia aerosol release,” he says. ies indicate that perfluoEllis also speculates that Ocean aerosols could concentrate PFO – on the surfaces rinated chemicals affect this process could muddy of bubbles, which loft it into the air. the liver, neonatal developone of the signatures that ment, the immune system, can be used to tell the difand hormone levels. Until recentPFOA in concentrations ranging ference between PFOA produced ly, PFOA had been widely used in from 200 to 800 parts per billion. with an electrochemical process stain repellents, polishes, and paOnce they analyzed the condensed (used by 3M) and that manufacper coatings. Manufacturers have aerosols, they found enrichment in tured with a different telomer probegun voluntary efforts to elimiPFO– and PFOA as a gas phase in cess (used by DuPont). nate its use. the vessel. The aerosols formed in PFOA produced with the telomThroughout this decade, scienocean water had the highest levels er process consists almost entirely tists interested in the widespread of enrichment, as much as 55-fold. of straight-chain isomers, and redistribution of PFOA and other Ellis and colleagues’ work helps search to date suggests that these perfluorochemicals have assumed explain PFOA movement, even if isomers are dominant in the Arcthat when PFOA enters bodies of the experimental concentrations tic. The electrochemical process water it stays there. This is because are about 1 million times greater results in a mixture of branchedthe predominant form of PFOA in than what is found in the environand straight-chain isomers. Ellis water is PFO–, an ionized species ment, notes oceanographic chemand colleagues speculate that beand potent surfactant with negliist Nobuyoshi Yamashita of Japan’s cause of the differences in physical gible vapor pressure. National Institute of Advanced Inproperties, the branched isomers Now, chemist David Ellis at dustrial Science and Technology. will tend to concentrate in water Trent University (Canada) and col“The high concentration is a limibodies such as the ocean and even leagues have turned this thinking tation, but [it’s] still useful as a prein rain, whereas linear isotopes on its head. From lab experiments liminary trial,” he says. will fractionate into the air. with high concentrations of PFOA, Ellis notes that the experiment Muir agrees that the new pathey report that aerosols can conhas direct relevance to the marine per presents fertile ground for field centrate PFO– on the surfaces of environment, where waves and studies. “I’m sure environmental bubbles, which loft the aerosols wind kick up sea spray, a natural chemists will immediately beinto the air. Once airborne, some of marine aerosol. As a surfactant, gin thinking of ways to confirm the PFO– converts to PFOA, which PFO– ought to concentrate on the whether this is important in the then moves into the atmosphere. surface of the water. The first meaambient environment,” he says. The scientists estimate that this surements confirming this surface —REBECCA RENNER
3908 ■ Environmental Science & Technology / June 1, 2008
© 2008 American Chemical Society
