|Unregulated and emerging chemical contaminants present numerous technical and institutional challenges to society and to environmental and public health professionals. Over the past four decades, increasingly sensitive analytical techniques have chronicled the emergence of specific chemicals in actual or potential sources of drinking water. As our ability to detect these agents has improved, the number of contaminants regulated under various environmental statutes has also increased, and the universe of regulated agents has grown dramatically. Despite these advances, many contaminants remain unregulated, and the number of such unregulated contaminants will continue to grow slowly over the next several decades. Thus, environmental professionals must make difficult risk management decisions regarding water resource and water supply management issues in the face of considerable regulatory uncertainty. Emerging chemical contaminants, such as industrial solvent stabilizers (1,4-dioxane), fuel oxygenates (MTBE and TBA), disinfection byproducts (NDMA), pharmaceuticals (antibiotics/drugs), personal care products (polycyclic musks), pesticides/herbicides (1,2,3-trichloropropane), and other persistent compounds such as flame retardants (PBDEs) and phthalates, illustrate many technical and institutional challenges. While technologies are available to remove many of these contaminants from water, such technologies are often expensive, and water treatment costs may not balance the estimated reduction in risk. Risk management decisions in the future will require more complex assessments of the vulnerability of a water supply source to unregulated contaminants, and an analysis of the appropriate combination of treatment processes in the context of water quality uncertainties to meet both current and future hazards arising due to these contaminants, taking cost into consideration.
In response to the challenges posed by emerging contaminants in water, the 18th Symposium in GRA’s Series on Groundwater Contaminants was held on June 7 and 8, 2006, at the Hilton Hotel in Concord, California. The symposium was dedicated to the topic of emerging groundwater contaminants. The symposium attracted over 160 participants, and showcased speakers from universities, research organizations, national laboratories, regulatory agencies and industry. The symposium was organized into 7 sequential sessions which are described in detail below. In addition, a poster session and student paper competition were organized for the evening of June 7. The symposium was sponsored by Locus Technologies, Malcolm Pirnie, Inc. and MWH Labs. Lunch, reception and refreshment sponsors included RMC Water & Environment, MWH, Daniel B. Stephens & Associates, Inc. and Shaw E&I, Inc.
The conference was organized to correspond with the GRA San Francisco Branch dinner meeting, a panel discussion that focused on setting regulatory standards for emerging contaminants. The three panelists were Dr. Rhodes Trussell of Trussell Technologies, Inc., Dr. Bruce Macler from US Environmental Protection Agency (EPA) and Dr. Robert Howd of California Office of Environmental Health and Hazard Assessment (OEHHA).
Session 1: Overview of Emerging Contaminants – Technical, Political and Institutional Challenges
The symposium began with an overview of technical challenges posed by emerging contaminants, presented by Dr. David Sedlak from the University of California at Berkeley. Dr. Sedlak discussed ways that emerging contaminants are first recognized, including examination of high-volume production chemicals, discovery of biological effects, and the development of analytical techniques. Case studies including perchlorate, NDMA, estrogens and selected PPCPs were used as examples to illustrate this process. Other technical challenges identified by Dr. Sedlak included analytical chemistry challenges in developing practical and standardized methods, continuing to improve models that predict contaminant transport and transformations, and the challenge of developing reliable and cost-effective treatment and remediation strategies.
Dr. Bruce Macler, a drinking water risk assessor from US EPA Region 9, summarized his perspective on emerging contaminants as a regulator. Dr. Macler emphasized that setting drinking water regulations for these contaminants is a lengthy process. He summarized groups of emerging contaminants, the scarcity of data on human health effects at environmental levels, effects on aquatic organisms, and other harmful effects. He described the Contaminant Candidate List (CCL) process and status of key compounds, concluding that Federal regulation and inclusion on the CCL is premature or unlikely for many emerging contaminants.
Dr. Janis Hulla, a pharmacologist for the US Army Corps of Engineers, provided an overview of Department of Defense’s (DoD's) strategic priorities for emerging contaminants. DoD is improving their responsiveness to emerging contaminants through the Materials of Evolving Regulatory Interest Team (MERIT). The MERIT program focuses on identifying, assessing, and managing DoD risks, improving science, and engaging internal and external stakeholders. Compounds currently on the DoD watchlist include NDMA, 1,4-Dioxane, 1,2,3-TCP, nanomaterials, DNT, PBDEs and others. Three compounds (perchlorate, RDX, and TCE) are on the MERIT's action list.
A legal perspective was presented by Brian Haughton, Esq. of Barg, Coffin, Lewis and Trapp, LLP. Mr. Haughton raised several philosophical questions about our attitudes towards environmental contaminants, science and policy.
The next talk, by Jon Rohrer of Worley Parsons Komex, provided a retrospective evaluation of MTBE as a case study of an emerging contaminant. Lessons learned from MTBE data include the importance of data collection (i.e., number of releases, mass released, fate and transport) and the need to revisit predictions as data and conceptual models improve.
Joseph Domagalski of USGS provided some perspective on pharmaceuticals in groundwater by relating USGS's ongoing efforts to monitor for a priority list of pharmaceuticals in the Groundwater Ambient Monitoring and Assessment (GAMA) program. Pharmaceuticals of interest were selected based on previous knowledge of occurrence, frequency of use and availability of analytical methods.
Session 2: Analytical Issues and Emerging Contaminants
The analytical challenges and recent advances in method development and approval were summarized by Dr. Jean Munch (USEPA Office of Research and Development). Dr. Munch described recent method development advances for nitrosamines, degradation products of acetanalide herbicides (alachlor, acetachlor and metolachlor), perfluoroalkyl compounds, and water-soluble volatile compounds. Dr. Andrew Eaton, laboratory director of MWH Labs, described the cycle of “discovery” of an emerging contaminant and the corresponding evolution of analytical methods for emerging contaminants. Dr. Eaton related the aspects of a highly evolved analytical method and used several examples to illustrate how methods for emerging contaminants have evolved over time.
Session 3: 1,2,3-Trichloropropane
During the second day of the conference, sessions focused on the latest developments and recent understanding of individual compounds, including 1,2,3-Trichloropropane (TCP), one of the more recent contaminants of concern. An overview of this compound was presented by Dr. Paul Tratnyek (Oregon Health and Science University), with an emphasis on treatment and remediation alternatives. Several case studies of 1,2,3-TCP plumes in agricultural areas of California were presented by John Fortuna of GeoSyntec Consultants to illustrate the effect of regulatory notification levels and laboratory detection limits on site management strategies, review laboratory treatability study results and summarize key factors for selecting an effective remediation strategy. Dr. Reid Bowman of Applied Process Technology, Inc. (APT) described the biological reduction of 1,2,3-TCP and other emerging contaminants by four orders of magnitude, or to below drinking water standards, using a hollow-fiber membrane biofilm reactor (MBfR). The technology was developed by Dr. Bruce Rittman at Northwestern University and has been licensed by APT.
Session 4: 1,4-Dioxane
Conference co-chair Tom Mohr of Santa Clara Valley Water District presented an overview of 1,4-dioxane, providing background on the history of 1,4-dioxane usage, plumes in the Santa Clara Valley Water District area, analytical methods, treatment/remediation methods, and state regulatory guidance. Farsad Fotouhi of Pall Corporation described efforts to characterize and remediate a large 1,4-dioxane plume in Michigan. Shaily Mahendra of UC Berkeley demystified aerobic biodegradation of 1,4-dioxane by identifying monooxygenase enzymes, showing biodegradation pathways and bacterial strains shown to degrade 1,4-dioxane in controlled laboratory studies. Patrick Evans of CDM summarized the performance of different biological treatment reactor configurations for removing 1,4-dioxane.
Session 5: N-Nitrosodimethylamine (NDMA)
An overview of NDMA occurrence, fate and transport in California groundwater was presented by Phyllis Stanin of Todd Engineers, drawing from five different case studies. Common themes included the persistence, length and shape of NDMA plumes at each of the sites and the commonality of plume spreading by pumping. Elisabeth Hawley from Malcolm Pirnie, Inc. described an alternative source of NDMA in groundwater, namely the formation of NDMA as a disinfection byproduct when wastewater is chloraminated followed by indirect potable reuse. The talk focused on NDMA and NDMA precursor removal during wastewater treatment, and control strategies for utilities. After lunch, Matthew Davie, from Stanford University, presented findings from his doctoral research investigating metal-catalyzed reduction of NDMA using powdered Fe, Fe-Ni, Pd, Pd-Cu, Ni, and Mn catalysts. This was followed by Bill Guarini from the Shaw Group illustrating an application of catalytic treatment for NDMA- and TCE-contaminated groundwater and the bench-scale and pilot-scale using Ni catalyst.
Session 6: Pharmaceuticals and Personal Care Products
Although the occurrence of PPCPs at trace levels has been established in surface waters, the human health effects are still uncertain. Dr. Richard Pleus from Intertox, Inc. summarized an ongoing AWWA Research Foundation study to review published literature on the toxicological significance of selected pharmaceuticals, measure concentrations in water supplies, and conduct a risk assessment. Dr. Jean Moran from Lawrence Livermore National Laboratory summarized the fate and transport of wastewater indicators (e.g., caffeine, DEET, alkylphenol carboxylic acids and selected pharmaceuticals) as a tracer for recycled water to quantify the fraction of recycled water in groundwater aquifers. Dr. Peter Fox, a professor from Arizona State University, summarized the fate of different pharmaceuticals and other trace organic compounds during soil aquifer treatment, following injection of tertiary treated wastewater.
Session 7: Other Emerging Contaminants
The final session of the day broadened symposium attendees’ concept of the next emerging contaminants and reminded them of the difficulty in assessing risks when little is known about chemicals of concern. Virginia Yingling of the Minnesota Department of Health related a case study investigating highly persistent and mobile perfluorinated compounds in groundwater. Dr. Eduard Hoehn of the Swiss Federal Institute for Water Science and Technology (EAWAG) shared preliminary results of a study of natural attenuation of emerging contaminants in downwelling reaches of streams augmented with recycled water. The final talk, given by Jenny Sterling of Daniel B. Stephens & Associates, Inc., addressed the nanotechnology industry as a source of new contaminants of concern as well as a useful tool for solving environmental problems. Ms. Sterling discussed the implications of nanoparticle behavior (e.g., different fate and transport mechanisms, conglomeration, colloid transport and size-dependent health effects) in the absence of a framework for assessing risks and setting regulations.
ABOUT THE AUTHORS
Elisabeth L. Hawley, an environmental engineer at Malcolm Pirnie, Inc. in Emeryville, CA, participated in the GRA symposium planning committee. She is working on a number of projects investigating the environmental fate and transport of emerging water quality contaminants and the effectiveness of a range of technologies for the removal of these contaminants from water resources.
Rula A. Deeb, is an Associate and Director of Applied Research/Strategic Consulting at Malcolm Pirnie, Inc. in Emeryville, CA. Dr. Deeb chaired the GRA symposium on emerging contaminants. She is currently managing several projects related to emerging contaminants.