Registration Dossier

Physical & Chemical properties

Viscosity

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Administrative data

Endpoint:
viscosity
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Justification for type of information:
1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
The basis for the adoption of a category approach for the three grades of processed Cashew Nutshell Extract is the commonality of the constituents and functional groups in the three grades and the common modes of action for specific localised endpoints that are manifest in physico-chemical, environmental fate and toxicological properties that are similar or follow a regular pattern as a result of structural similarity. The ECHA Final Decisions on the Annex IX and X (mammalian toxicology, ecotoxicology and environmental fate) Testing Proposals for three grades confirmed the applicability of a category approach which involves reading data across from the source substances Cashew Nutshell Extract, Decarboxylated, Distilled (Distilled Grade) and Cashew Nutshell Extract, Decarboxylated, Distillation Residue (Distillation Residue Grade) to the target substance Cashew Nutshell Extract, Decarboxylated (Technical Grade) by interpolation. In this context interpolation is “the estimation of a value for a member of the group using measured values from other members on both sides of that member within the defined group spectrum”. Further details on the justification for using the interpolation based read-across approach are given in the attached document “Report on the grouping and read-across rationale for the three grades of processed Cashew Nutshell Extract”. For the Annex VII and VIII endpoints a programme of testing has been carried out to provide comparative information for the three grades and develop a data matrix to support the category and read-across approaches. This has involved generating reliable data for all Annex VII and VIII physico-chemical and environmental fate endpoints and certain mammalian toxicity properties. However, based on the discussions surrounding the Final Decisions it was not considered necessary to apply this approach retrospectively to address all identified data gaps at Annexes VII and VIII. The original data used for the registration of a single substance (Cashew Nutshell Liquid, CAS Number 8007-24-7) was largely based on data for Distilled Grade since this was considered to be the most (eco) toxicologically active form, given the higher content of low molecular weight constituents (such as cardanol) and the low content of polymeric species. However, for the short-term acute aquatic toxicity endpoints the testing on algae, invertebrates and fish was carried out on Technical Grade. The measured data for the key physico-chemical properties that underpin the likely short term aquatic toxicity of the three grades, namely water solubility and octanol-water partition coefficient, are consistent. Therefore, based on the use of the category approach it is considered appropriate to read-across from the existing viscosity data for Technical Grade to the other two grades.
2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL)
For the viscosity endpoint no test data is available for the registered substance Technical Grade. However, data is available for the compositionally similar substance Technical Grade which is part of the category of the three grades of CNSL. The measured data for viscosity provides values of 265 to 294 centipoise for two samples of Technical Grade. The values for the measured physico-chemical parameters for the three grades are consistent and generally show limited variability. Therefore, it is considered appropriate to read-across from the data for Distilled Grade to Technical Grade with the result that it has been estimated that the viscosity of Technical Grade will be between 265 and 295 centipoise.

Data source

Materials and methods

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Batch Number: 117992

Results and discussion

Viscosity
Temp.:
other: 25 °C
Parameter:
other: cps
Value:
294

Applicant's summary and conclusion

Conclusions:
Read-across from the data for Distilled Grade to Technical Grade is considered appropriate. The result from one batch tested (No: 117992) was 294 so it is estimated that the viscosity of Technical Grade will be around this value.
Executive summary:

For the viscosity endpoint no test data is available for the registered substance Technical Grade. However, data is available for the compositionally similar substance Distilled Grade which is part of the category of the three grades of CNSL. The measured data for viscosity provides values of 265 to 294 centipoise for two samples of Distilled Grade. The values for the measured physico-chemical parameters for the three grades are consistent and generally show limited variability. Therefore, it is considered appropriate to read-across from the data for Distilled Grade to Technical Grade with the result that it has been estimated that the viscosity of  Technical grade will be between 265 and 295 centipoise.