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well. While PFOA is known to be carcinogenic to animals, its relevance to human health is yet unknown and is something the EPA is still evaluating. For the time being, the EPA describes PFOA as "likely to be carcinogenic to humans." Clearly, the recent updates to the regulatory limits were in order. How Do We Sample For Them? The trace background levels of PFCs, combined with the low- level reporting and regulatory limits, require a careful sampling protocol utilizing measures to prevent cross contamination, which is of utmost importance in obtaining valid results. Trace background levels may be present both in the field and at the laboratory, like that from rain or some drinking water systems; thus, cross contamination effects can be difficult to quantify. Therefore, sampling for these compounds is not your typical routine sampling event and analysis program. Initial sampling protocols were extremely stringent, with field staff needing to be careful of what they wore, the equipment they used, and even what they ate. As we have progressed in our knowledge and testing of PFOS and PFOA, protocols have already been modified and items taken off the "do not use" lists. As always, quality control samples are a must, and water for equipment decontamination must be tested to be PFC- free. Laboratories can incidentally cross-contaminate samples during either extraction or analysis. On top of that, analytical methods and capabilities are still being developed for this group of compounds. Not only are sampling and analysis for PFCs difficult, but also the fate and transport of these compounds are still largely unknown. As previously mentioned, PFCs are chemically and biologically stable in the environment and resist degradation, have low volatility, and are generally water-soluble, thus highly mobile. However, most precursor compounds to PFOA and PFOS can neither be characterized nor quantified, and biotransformation and oxidation rates in the environment are unknown. There is much to be learned about PFC plumes through upcoming site characterizations and collaboration among the professionals evaluating the results. The more we know about PFCs, the better we can address the problem and alleviate their impacts on human health and the environment. Many types of both in-situ and ex-situ treatment techniques have been utilized in the search for the best, most cost-effective treatment of PFCs. While currently available techniques, such as activated carbon adsorption (the "best" option identified to date), excavation and disposal, biological treatment, thermal treatment, and chemical oxidation have been assessed, researchers continue to toil as they look for the ultimate remedy. Where Do We Go From Here? There are many PFC compounds with varying characteristics and formulations/compositions that impact the development of appropriate regulatory limits. In addition, the background level and cross contamination issues, lack of experienced field and laboratory staff, and the existence of large, potentially comingled plumes will certainly impact the ultimate handling of PFC contamination and remediation costs. In New York, we have already seen the Department of Environmental Conservation (DEC) require analysis of these compounds at sites contaminated by other compounds of concern, leading to delayed spill closures and opening new spill numbers. With public interest in PFOS and PFOA heightened by recent news reports, will the DEC soon request to re-open "Closed" spill sites, such as crash sites where AFFF was used? And what about known heavy-use locations, such as fire training centers? With the ubiquitous use of products containing PFC chemicals, along with the chemicals' low volatility and fast mobility, will we be able to discern between background levels and appropriate regulatory limits? Should regulatory limits be increased or decreased? And what about indoor air quality? Only time will tell. In the future, we can expect that as more contaminated sites are identified, studied, and analyzed, we will gain a better understanding of the compounds' fate and transport and health effects, leading to new regulations, modified sampling and analytical methods, and effective remediation techniques. n wateronline.com n Water Innovations 9 REGULATORYCOMPLIANCE Greta White is a geologist with 11 years of experience in the environmental consulting industry. She is skilled in site investigations and remedial activities for government, commercial, indus- trial, and residential sites in NY, NJ, PA, VT, and MA that have been impacted with PCBs, chlorinated solvents, petroleum, PFCs including PFOA/PFOS, and other constituents of concern. She has participated in all phases of project execution from the pursuit phase through project closeout. Greta can be reached at gwhite@walden-associates.com. About The Author Before PFCs were extinguished from the formula, firefighting foam was a leading source of PFOS/PFOA pollution — and the contamination persists. Not only are sampling and analysis for PFCs difficult, but also the fate and transport of these compounds are still largely unknown.