SETAC Globe - Environmental Quality Through Science
  December 2010
Volume 11 Issue 12

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Ascona, Switzerland

Scientific Report for TransCon2010―Environmental Transformation of Organic Compounds: Towards a Joint Perspective on the Importance of Transformation Products as Environmental Contaminants

Organizers: Kathrin Fenner (Eawag, Switzerland), Juliane Hollender (Eawag, Switzerland), John Sumpter (Brunel University, UK)

Transformation products of organic contaminants formed in the environment might, and in some cases are known to be, more persistent, bioaccumulative and/or toxic than their parent compounds. They are therefore considered an emerging issue in environmental chemistry and toxicology. Since consistent methodologies for their assessment are missing and environmental toxicology and chemistry data on transformation products are in most cases sparse, an international conference on the topic, TransCon2010, was convened on Monte Verità, Ascona, Switzerland, in September of this year. In line with SETAC’s philosophy, the conference brought together academic, regulatory and industry participants, many of whom are members of SETAC, to develop a common understanding of how much transformation products contribute to the overall chemical risk in the environment and of how to deal with transformation products in chemical risk assessment and environmental quality assessment.

Defining the scientific state-of-the-art
In the opening keynote lecture, John Sumpter (Brunel University) set the basis for discussing the importance of transformation products by pointing out that the overall goal of environmental toxicology and chemistry research should be to protect the environment and that therefore our focus should be on those transformation products that are of most ecotoxicological concern. Over the course of the conference, several cases of such known, problematic transformation products were presented including well-known cases such as the transformation of DDT to its toxic and persistent transformation product DDE, but also some more recently discovered issues such as the photodegradation of triclosan to toxic products (Kris McNeill, ETH Zurich) or formation of drinking water disinfection by-products linked to carcinogenic effects in humans (Susan Richardson, U.S. EPA).

Sessions on Monday and Tuesday on analytical tools for the identification of transformation products, reconnaissance and field studies and laboratory-based studies on the chemical and biological formation of transformation products demonstrated that current research on transformation products is focused heavily on assessing exposure to transformation products. Analytical approaches to identify transformation products, including high-resolution mass spectrometry, and 1- and 2-dimensional NMR techniques, were pointed out by Thomas Ternes (BAFG). Juliane Hollender (Eawag) presented an overview of quantitative analyses of transformation products present in the aquatic environment in trace concentrations, thus demonstrating that highly sensitive and temporally- and spatially-resolved monitoring of transformation products is possible and ongoing at different institutions.

Sessions on Wednesday discussed models to predict environmental exposure to transformation products (Kathrin Fenner, Eawag) and structure-based approaches to predict rates and pathways of different transformation processes (Gerrit Schüürmann, UFZ Leipzig), thus further emphasizing the diversity of ongoing exposure-related research. Presentations on attempts to predict biotransformation pathways of micropollutants were nicely contrasted by Perry McCarty’s (Stanford University) historical perspective on microbial transformations of chlorinated solvents, which also enumerated some of the challenges in predicting these transformations considering general principles of microbiology.

Sessions on Thursday were dedicated to effects and risk assessment of transformation products. They featured experimental and model-based approaches to assess ecotoxicological and human health effects of transformation products relative to their parent compounds (Beate Escher, University of Queensland). These sessions clearly demonstrated the large data gaps on the effects side, and also emphasized the uncertainties concerning transformation product data and the resulting difficulties that regulatory authorities (Mark Bonnell, Environment Canada) and chemical and pharmaceutical industry (Jason Snape, Astra Zeneca) are confronted with when including transformation products in chemical risk assessments. Finally, ongoing research on the transformation of nanoparticles in the environment was presented by Joel Pedersen (University of Wisconsin-Madison) and identified as another very complex scientific field that is only just started being investigated in a systematic manner.

Research opportunities
Besides the keynotes and regular conference contributions as poster or platform presentations, four workshops that were aimed at deepening the discussion on specific topics and particularly pointing out promising new research opportunities were run concurrently. The four working groups addressed:

The three most important visions that came out of the working groups were (i) establishing a closer link between exposure and effect assessment of transformation products through the concept of effect-driven transformation studies, (ii) promoting the more extensive use of a number of existing databases to develop tools that predict the probability and likely routes of chemical and biological transformations, and (iii) developing methods to “read across” from existing experimental data on the parent compound to facilitate property prediction for the transformation products. Emphasis was placed on the importance of cooperation between the regulators who use transformation product data, the industries that own those data, and the researchers developing predictive models from the data.

The organizers of the conference thank the sponsors, which included Centro Stefano Franscini (ETH Zürich), the Swiss National Science Foundation, the Swiss Federal Institute for Aquatic Science and Technology (Eawag), the Swiss Federal Office for the Environment (Bafu), Thermo Fisher Scientific (Schweiz) AG, Nestlé AG, F. Hoffmann-La Roche Ltd, and the Norman network of reference laboratories for monitoring of emerging environmental pollutants.

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