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 and 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 that list further 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? Motivated by this challenge, a workshop of 24 experts was convened in August 2009 with the express purpose of answering this question. The participants were specifically chosen to encompass the broad spectrum of disciplines with insight into the issue's many different facets, including toxicology; pharmacokinetics; pharmacology; risk assessment; contaminant fate and transport; chemical bioaccumulation, bioavailability and persistence; chemical parameter estimation and modeling; analytic chemistry; chemical production, use and disposal, and monitoring and assessment technology. It is the intent of this seminar to summarize the discussions, conclusions, and identification of challenges that have evolved (so far) out of the workshop.
In order to create a prioritized list of contaminants (and groups of contaminants) of greatest concern, the considerations that must be integrated are neither simple nor few in number. They must include the substance's environmental persistence, its toxicity or otherwise deleterious environmental impact, its type and number of health end-points, its frequency of occurrence and volume of production, and its likelihood to accumulate or be disposed in such a way as to create geographic hot spots with a high potential for human exposure. Equally importantly, an algorithm is needed that delineates the judgments and measurements necessary to maintain the relevance of the list as new information, tools, and techniques are developed and as yet unconsidered contaminant candidates are identified or come on the market. This is not to say that what have historically been the primary actors in Superfund are still not necessary targets for study in both present and future Superfund sites. However, they should be evaluated comparatively along with pollutants in the poorly defined and rapidly broadening list of emerging contaminants as we attempt to predict what the next generation of Superfund sites will look like and how to prioritize finite budgets to minimize the likelihood of their creation.
This webinar is sponsored by the NIEHS Superfund Research Program (www.niehs.nih.gov/research/supported/srp/).