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Emerging Decontaminants Hans Peter H. Arp* Norwegian Geotechnical Institute, Oslo, Norway radar or for which analytical methods did not exist until recently. One example is hexabromobenzene, whose ubiquitous presence is now gathering attention, despite it likely being produced at high volumes since the 1970s.3 To make things more complicated, there are “emerging contaminants within complex mixtures”, such as industrial effluents, oil residues, hospital effluent, etc. of which either the mixture itself or newly identified (subgroups) of components within may be considered emerging contaminants. Perhaps most complex of all are “transformation derived” emerging contaminants, which are pernicious metabolization or transformation products of emerging contaminants, legacy contaminants, or benign chemicals. However, even with this separation in terms, the nature of what makes these subgroups “emerging” continues to remain elusive. Are they “emerging in their identification,” “emerging in the challenges they present”, “emerging in concern” or simply “emerging in interest”? The difficulty in forming a consensus definition for “emerging contaminants” reflects the central problem that many contaminants areand will continue to beoff the radar. Further, it is too easy for industry to slightly alter their recipes to replace highly regulated contaminants with nonregulated emerging contaminants.2,4 The sheer number of existing and potential emerging contaminants dwarfs the pace of research to address the risks they pose, despite rapid progress and breakthroughs for certain subgroups. How can environmental scientists best serve regulators for developing effective policy for dealing with the unknown threats from unknown emerging contaminants? Two general approaches are available. The first, more generally used, is a “clean-up” approach, and that is to develop background documentation and data to support regulations on individual or groups of emerging chemicals. This approach has been met with some, though sometimes slow, success, with examples like the Montreal Protocol, REACH, and the Stockholm Convention on Persistent Organic Pollutants. The second, less discussed, is a “prevention” approach, and that is to use what we learned from emerging contaminants to help industry make commercially viable, environmentally benign replacements. Let us call these replacements, if truly environmentally benign, emerging decontaminants. This approach is, in essence, reflecting the green chemistry principles of “less hazardous chemical synthesis” and “designing safer chemicals”.5 Research directed toward identifying emerging decontaminants is the dialogue that needs to develop between industry, environmental scientists, and regulators. This dialogue involves industry communicating what properties they need their chemicals to have for their products (fire proofing, plasticizing,
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hreats from emerging contaminants continue to be a driving forceif not a rallying cryfor innovation in environmental research. As the adjective “emerging” implies little is known about these contaminants, from their production volumes, to their physical−chemical properties, to their effects on humans and the environment, to how best to regulate the unknown risks they pose. These unknowns can only be addressed with adaptation, exhaustive lab work, and extensive trial-and-error. Pay-offs for taking on these challenges can go beyond environmental protection. For instance, research into poly- and perfluorinated chemicals led to improvements in models that predict physical-chemical properties, advanced liquid chromatography methods, and shed new light on uptake mechanisms of protein-bound organic chemicals, to name a few payoffs. But, where is emerging contaminant research ultimately going? Will there always be emerging contaminants around the corner? Despite its utility, the term “emerging contaminants” remains problematic. What qualifies a contaminant to be considered “emerging”? From a 2006 special emerging contaminant issue of ES&T, “the definition [...] is a bit elusive, because what is emerging is a matter of perspective as well as timing.”1 The elusiveness of this term remains true in 2012. One possible approach is to divide the term into subcategories. For instance, there are “new” emerging contaminants, which are chemicals that are recently manufactured and suddenly appear everywhere, such as decabromdiphenylethane being a sudden replacement for decabromyldiphenylether.2 Then there are “old” emerging contaminants, which are the ones that were actually around for several decades, but simply were not on the © 2012 American Chemical Society
Received: March 19, 2012 Accepted: March 22, 2012 Published: March 30, 2012 4259
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targeted insect killing etc.), and environmental scientists assisting them to identify which of the potentially commercially viable alternatives are benign. In this role, environmental scientists would be either independent consultants, or hired directly by industry, or participating through interdisciplinary research projects with synthetic chemists and material scientists. The role of the regulator would be to provide appropriate incentives for development and implementation of the identified decontaminants. The toolbox that environmental scientists would use for this would be founded on emerging contaminant research: same analytical methods, same toxicity assay procedures, same property tests, same models. It simply implies turning the focus of emerging contaminant research on its head. The models and test systems developed to estimate persistency, bioaccumulation and toxicity in the environment would be used to ensure that emerging decontaminants are persistent in the material they are applied to but not in the environment, either because of rapid degradation, negligible sorption to organisms, low toxicity, or all three. These steps can be further integrated into the remaining aspects of green chemistry, by taking into account other pertinent issues like carbon and contaminant emissions during the life cycle of chemical production and the products they are applied to. A true emerging decontaminant would, through market and regulatory forces, decontaminate the products where emerging contaminants were applied previously or would have been applied to. Research in emerging contaminants needs to continue as it is one the most needed and challenging aspects of environmental science. But, this research should also be developed in a preventative direction to help and encourage industry to develop commercially viable decontaminants. The complexity of this research cannot be underestimated; developing a cure is more complicated than diagnosing the disease, as is finding the solution more difficult than identifying the problem. Ultimately, the direction of emerging contaminant research should be toward an emerging contaminant free future.
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AUTHOR INFORMATION
Corresponding Author
*Phone: +47 9502 0667; e-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Field, J. A.; Johnson, C. A.; Rose, J. B. What is ″emerging″? Environ. Sci. Technol. 2006, 40 (23), 7105−7105. (2) Kierkegaard, A.; Björklund, J.; Friden, U. Identification of the flame retardant decabromodiphenyl ethane in the environment. Environ. Sci. Technol. 2004, 38 (12), 3247−3253. (3) Arp, H. P. H; Moskeland, T.; Andersson, P. L.; Nyholm, J. R. Presence and partitioning properties of the flame retardants pentabromotoluene, pentabromoethylbenzene and hexabromobenzene near suspected source zones in Norway. J. Environ. Monit. 2011, 13 (3), 505−513. (4) DiGangi, J.; Blum, A.; Bergman, Å.; de Wit, C. A.; Lucas, D.; Mortimer, D.; Schecter, A.; Scheringer, M.; Shaw, S. D.; Webster, T. F. San Antonio statement on brominated and chlorinated flame retardants. Environ Health Perspect 2010, 118, 12. (5) Anastas, P. T.; Warner, J. C. Green Chemistry: Theory and Practice; Oxford University Press: New York, 1998; p 152.
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