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Short-term toxicity to aquatic invertebrates

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Description of key information

The acute toxicity of XDI to Daphnia magna was tested in a semi-static test system in accordance with OECD guideline 202 and the principles of Good Laboratory Practice. Test solutions were prepared by adding XDI to test medium, and allowing the substance to dissociate completely. The results were expressed as mean measured concentrations of the transformation product XDA (instead of nominal concentrations of XDI) and subsequently recalculated to the parent material XDI. So, the 48h-EC50 values were 6.2 mg XDA/L  and 8.6 mg XDI/L.
The acute toxicity of XDA to Daphnia magna was tested in a static test system in accordance with OECD guideline 202 and the principles of Good Laboratory Practice. The results were expressed as analytically confirmed nominal concentrations XDA and subsequently recalculated to the dossier substance XDI. So, the 48h-EC50 values were 15.2 mg XDA/L and 21 mg XDI/L.
The means are used as key values for chemical safety assessment and for classification purposes.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
9.7 mg/L

Additional information

The results of the study performed with XDI was expressed as mean measured concentrations of the transformation product XDA. Based on the rapid transformation of the parent material XDI, this is deemed more relevant as the test organisms are indeed not exposed to the parent material XDI but to its transformation product XDA. Based on the latter, it was deemed important to evaluate the toxicity of the pure transformation product XDA.

Both studies were reviewed and determined to be reliable. The results of both studies also were of the same magnitude. Although the XDA studies received a lower Klimisch value due to the pH issue, it was judged that the pH issue did not influence the results of the study and thus it is deemed that the results put the same weight into the scale of the weight of evidence.

The means for the aquatic invertebrates are:

Key value for chemical safety assessment: 48 h-EC50 for freshwater invertebrates: 9.7 mg XDA/L (geometric mean of 6.2 and 15.2 mg XDA/L)

Key value for CLP classification: 48h-EC50 for freshwater invertebrates: 13.4 mg XDI/L (geometric mean of 8.6 and 21 mg XDI/L)