Superfund Contaminants: The Next Generation
August 12-14, 2009
As of January 2006, there were more than 239,000 substances on the Chemical Abstracts Service list of regulated chemicals. The production of more than 4,800 of these chemicals exceeded 1,000 metric ton/year. This total does not include the massive quantities of "naturally occurring" contaminants that may enter the human environment due to resource extraction or production, such as mining, groundwater pumping, and agricultural practices. That said, how is it possible to identify those contaminants of most environmental concern, and then winnow the list down to those contaminants most likely to be the foci of attention in future mega-contamination sites? In short, how can we identify the contaminants most likely to create the next generation of Superfund sites? This was the question tackled by the 24 experts assembled at the NIEHS Workshop entitled "Superfund Contaminants: The Next Generation".
The workshop participants were selected to ensure expertise in such areas as toxicology, pharmacokinetics, pharmacology, contaminant fate and transport, chemical bioaccumulation, bioavailability and persistence, chemical parameter estimation and modeling, hazardous substance production and disposal, and monitoring and assessment technology. The meeting itself was structured to maximize the amount of interaction between and discussion from all participants. The workshop agenda was composed primarily of breakout sessions; each focused on addressing a particular aspect of the problem. Breakout sessions were followed by full assembly synthesis sessions in which the full body of participants discussed the outcomes of the preceding breakout sessions. The initial question tackled by the participants was what attributes delimit emerging Superfund contaminants as distinct from the broader universe of emerging contaminants in general. Persistence, volume of production, likelihood of toxicity, and tendency to accumulate rather than disperse were some of the attributes commonly identified as defining emerging Superfund contaminants.
Relying on and further refining the answer to this first question, the next task undertaken was to develop a Top Ten Candidate List of chemicals or groups of chemicals that are recommended for consideration by SRP. Commonly identified chemicals of concern included phthalates, brominated flame retardants, polyfluorinated organic compounds, and siloxanes. Some breakout groups felt that it was more appropriate and instructive to identify top processes rather than chemicals that are likely to create the next generation of Superfund sites. For example, electronics recycling, land application of wastewater biosolids, disposal of landfill leachate, and photovoltaic solar panel manufacturing were identified as industrial processes likely to generate heavily contaminated sites with contaminants of future concern. The next task undertaken by the workshop participants was identifying and prioritizing the research and information gaps that need to be addressed regarding the chemical (and/or process) candidate lists developed in the earlier session. In order to increase the practical value of the gaps analysis, a second round of discussion sessions was convened with the objective being to draft specific mock research proposal calls, such as might be posted by NIEHS, along with their correlated research approach and outcomes.
During the course of the workshop, sections of draft text were composed to archive, provide bases for subsequent discussion, and refine the discussion's outcomes. Included in the text were suggestions for next steps in research with the specific focus on better delimiting the list of chemicals and processes of future concern to the SRP. The participants of the workshop will author a paper describing the outcomes of the workshop discussions. The workshop organizers and executive committee are currently preparing the first draft of this paper, which will then be reviewed by all workshop participants with an eye to finally developing a consensus document. The concept for the paper and some initial draft text was submitted to Environmental Health Perspectives (EHP) for preliminary review as to appropriateness for publication. The editor of EHP has responded that the material would be accepted for review as a commentary piece in the journal and work is moving forward with that venue in mind. Submission to EHP is targeted in early 2010.