Considerations of temperature in the context of the persistence classification in the EU

Autor(en): Matthies, Michael
Beulke, Sabine
Stichwörter: Arrhenius equation; CHEMICALS; Degradation simulation testing; Environmental Sciences; Environmental Sciences & Ecology; Environmental temperature; Exposure assessment; Hazard; PBT assessment; Persistence criteria; Temperature normalisation
Erscheinungsdatum: 2017
Volumen: 29
Simulation degradation studies for industrial chemicals, biocidal products and plant protection products are required in the EU to estimate half-lives in soil, water and sediment for the comparison to persistence criteria for hazard (P/vP) assessment, and for use in exposure assessments. There is a discrepancy between European regulatory approaches regarding the temperature at which degradation half-lives should be (1) measured in simulation degradation testing of environmental compartments, and (2) compared to the P/vP criteria. In this paper, an opinion is provided on the options for the experimental temperature and extrapolation to other conditions. A review of the historical development of persistence criteria did not give conclusive evidence of the temperature at which the half-lives that underpin the P-criteria were measured, but room temperature is likely. Half-lives measured at 20 degrees C are in line with the intentions of some international agreements, but in the EU there is a continued political debate regarding the relevant temperature for comparison with persistence criteria. Measuring degradation at 20 degrees C has the advantage that metabolites/transformation products can be identified with greater accuracy, and that kinetic fits to determine half-lives for parent compounds and metabolites carry less uncertainty. Extrapolation of half-lives to lower temperatures is possible for assessing environmental exposure, but the uncertainty of the persistence classification is smaller when measured half-lives are used for direct comparison with P/vP criteria, without extrapolation. Model simulations demonstrate the pattern of concentrations that can be expected for realistic worst case climate scenarios in the EU based on the half-life of 120 days in soil at 20 degrees C and of 40 days in water at 20 degrees C, and their temporal and spatial variability.
ISSN: 21904707
DOI: 10.1186/s12302-017-0113-1

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