Indicators for the Exposure Assessment of Transformation Products of Organic Micropollutants
journal contributionposted on 01.04.2007, 00:00 by Lukas Gasser, Kathrin Fenner, Martin Scheringer
Environmental transformation products of organic micropollutants have the potential to be similarly or even more mobile, persistent, or toxic than their parent compounds. They should, therefore, be included in chemical hazard and risk assessment procedures as well as in the assessment of soil and water quality. To fulfill this requirement most efficiently, screening approaches that select relevant transformation products for detailed assessment are needed. This paper presents two process-based multimedia, multispecies models that allow us to quantitatively estimate the environmental fate of transformation products. The resulting exposure patterns are assessed with two indicators: joint persistence (JP), which describes the temporal extent of environmental exposure to a parent compound and its transformation products, and the predicted relative aquatic concentrations (RAC), which estimate the relative concentrations of parent compounds and their transformation products in surface water bodies. As a case study, JP and RAC are calculated for 16 pesticides and their relevant transformation products. The results for the JP indicator confirm the importance of considering transformation products in the assessment of overall persistence; for example, in the context of PBT assessments. Comparison of RAC results with monitoring data on herbicides and their transformation products shows the suitability of our approach for estimating relative concentra tions in surface water, and as a consequence, its usefulness in identifying transformation products for future water quality monitoring programs. Transformation products of triketones and other highly used acidic herbicides are specifically identified as targets.