Recent advances in environmental risk assessment of transformation products

Escher, Beate I. and Fenner, Kathrin (2011) Recent advances in environmental risk assessment of transformation products. Environmental Science and Technology, 45 9: 3835-3847. doi:10.1021/es1030799

Author Escher, Beate I.
Fenner, Kathrin
Title Recent advances in environmental risk assessment of transformation products
Journal name Environmental Science and Technology   Check publisher's open access policy
ISSN 0013-936X
Publication date 2011-05-01
Sub-type Critical review of research, literature review, critical commentary
DOI 10.1021/es1030799
Volume 45
Issue 9
Start page 3835
End page 3847
Total pages 13
Place of publication Washington, DC, United States
Publisher American Chemical Society
Language eng
Formatted abstract
When micropollutants degrade in the environment, they may form persistent and toxic transformation products, which should be accounted for in the environmental risk assessment of the parent compounds. Transformation products have become a topic of interest not only with regard to their formation in the environment, but also during advanced water treatment processes, where disinfection byproducts can form from benign precursors. In addition, environmental risk assessment of human and veterinary pharmaceuticals requires inclusion of human metabolites as most pharmaceuticals are not excreted into wastewater in their original form, but are extensively metabolized. All three areas have developed their independent approaches to assess the risk associated with transformation product formation including hazard identification, exposure assessment, hazard assessment including dose-response characterization, and risk characterization. This review provides an overview and defines a link among those areas, emphasizing commonalities and encouraging a common approach. We distinguish among approaches to assess transformation products of individual pollutants that are undergoing a particular transformation process, e.g., biotransformation or (photo)oxidation, and approaches with the goal of prioritizing transformation products in terms of their contribution to environmental risk. We classify existing approaches for transformation product assessment in degradation studies as exposure- or effect-driven. In the exposure-driven approach, transformation products are identified and quantified by chemical analysis followed by effect assessment. In the effect-driven approach, a reaction mixture undergoes toxicity testing. If the decrease in toxicity parallels the decrease of parent compound concentration, the transformation products are considered to be irrelevant, and only when toxicity increases or the decrease is not proportional to the parent compound concentration are the TPs identified. For prioritization of transformation products in terms of their contribution to overall environmental risk, we integrate existing research into a coherent model-based, risk-driven framework. In the proposed framework, read-across from data of the parent compound to the transformation products is emphasized, but limitations to this approach are also discussed. Most prominently, we demonstrate how effect data for parent compounds can be used in combination with analysis of toxicophore structures and bioconcentration potential to facilitate transformation product effect assessment.
Keyword Effect-Directed Analysis
Ecotoxicological Hazard Assessment
Trap Mass-Spectrometry
Waste-Water Treatment
Base-Line Toxicity
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Received: September 8, 2010. Accepted: March 18, 2011. Revised: March 12, 2011. Published: April 07, 2011

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collections: Official 2012 Collection
National Research Centre for Environmental Toxicology Publications
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