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Sylvia Karlsson Swedish Chemicals Inspectorate

This course on 26-27 January 2005 by Sylvia Karlsson with Swedish Chemicals Inspectorate focuses on degradation kinetics, regulatory endpoints, and kinetic models for parent compounds and metabolites in soil and water/sediment systems. Learn to compare kinetic endpoints against criteria from regulatory directives for ecotoxicology. Understand the use of kinetic endpoints in calculating PECsoil, PECgw, PECsw, and PECsed, and how to apply them to triggers and further studies. Explore the application of kinetic models and formation fractions in simulations and field studies for environmental risk assessments. Gain insights on deriving DT50 and DT90 values and the significance of rate constants in ecotoxicological assessments.

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Sylvia Karlsson Swedish Chemicals Inspectorate

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  1. FOCUS Degradation KineticsTraining course 26-27 January 2005Regulatory use of degradation endpoints Sylvia Karlsson Swedish Chemicals Inspectorate

  2. Parent compounds, soil: DT50, DT90 or rate constant, kinetic model Metabolites, soil: DT50, DT90 or rate constant, kinetic model, formation fraction Parent and metabolites, water/sediment: DT50, DT90 or rate constant, kinetic model, (formation fraction) – for overall system, water column and sediment What are the kinetic endpoints?

  3. To compare with criteria, triggers for further studies, as provided in Annex II, III and VI of Dir. 91/414/EEC and in Guidance Documents on Aquatic and Terrestrial Ecotoxicology As input to calculations of PECsoil, PECgw, PECsw and PECsed What are the kinetic endpoints used for?

  4. Use against triggers (parents & metabolites): DT50 and DT90 derived by best-fit kinetics (unless deviation from first order kinetics can be attributed to experimental artefact!)Degradation or dissipation endpoints?- Mainly left to users to decide. What endpoints are used for different purposes (triggers/PEC)?

  5. PECgw, PECsw and PECsed – calculated e.g. by FOCUS simulation tools: DT50 or rate constant, for metabolites also formation fraction, derived by first order kinetics (1st tier).Data from lab or field studies.Endpoints from field studies must be normalised.

  6. PECsoil calculated by spreadsheets or parameter estimation software: DT50 or rate constant, for metabolites also formation fraction, Endpoints derived by best-fit kinetics. Data from lab or field studies.

  7. For use against triggers and to calculate PECsoil:Values not averaged (normally!) To calculate PECgw, PECsw and PECsed:Averaged values (normally!) Average or representative worst-case values?

  8. Rate constants and DT50s: Geometric – pragmatic reason: produces equal results Other parameters (e.g., formation fractions): Arithmetic Geometric or arithmetic mean?

  9. DT50 and DT90 obtained by different kinetic models can be averaged. Specific recommendations are provided for metabolite endpoints and for use of endpoints for calculation of PECgw, PECsw and PECsed when first order kinetics does not provide an adequate fit. Finally,

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