| Popis: |
The intrinsic variability in chemical composition and the sometimes unknown speciation of inorganic UVCBs (Unknown or Variable composition, Complex reaction products, or Biological materials) result in uncertainties during their assessment, requiring the development of a specific approach. The strategy for the assessment focuses on capturing the variability in composition using the knowledge of processes and input materials, defining the ranges in composition as well as the chemical speciation where applicable, compiling the hazard profiles of the constituents and classifying the UVCB based on the combination of these data. Elemental concentrations of the UVCB constituents are usually measured due to their economic value, allowing to document the variability in composition. Speciation, preset by the input material and process is not routinely quantified. Where the speciation of the constituent is unknown, the speciation with the worst-case classification can be taken forward for the calculation of the UVCB classification. For the risk assessment, the hazards of each constituent are assessed and the corresponding effect values (e.g. PNEC, DNEL) taken forward where a hazard is identified. Workplace monitoring and environmental release data as well as metal-specific models are used in exposure assessment. The potential combined exposure and toxicity of the UVCB constituents are assessed in a tiered way, starting from the conservative summation of the RCRs, further refined with additional information. |
