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Short-term toxicity to fish

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Description of key information

Experimental data regarding the acute toxicity to fish for CAS 16111-62-9 are not available. CAS 16111-62-9 hydrolyses instantly when released to the aqueous phase. The main degradation product is 2-ethylhexan-1-ol (CAS 104-76-7) which is formed at a proportion of 84.4-96.9 %. In addition, 2-ethylhexan-1-ol is more toxic than the other degradation products formed from CAS 16111-62-9. Therefore, results (QSAR calculated as well as experimental) for 2-ethylhexan-1-ol are deemed appropriate in the risk assessment of CAS 16111-62-9.
The lowest observed value for 96-h acute fish toxicity of 2-ethylhexan-1-ol is LC50 = 16.207 mg/L.

Key value for chemical safety assessment

LC50 for freshwater fish:
16.207 mg/L

Additional information

No test results on the acute toxicity to fish are available for bis(2-ethylhexyl) peroxydicarbonate. bis(2-ethylhexyl) peroxydicarbonate hydrolyses instantly when released to the aqueous phase (half-life < 1 h). The main degradation product of bis(2-ethylhexyl) peroxydicarbonate is 2-ethylhexan-1-ol (CAS 104-76-7) which is formed at a proportion of 84.4–96.9 %. In addition, 2-ethylhexan-1-ol is more toxic than the other degradation products formed from CAS 16111-62-9. Therefore, results for 2-ethylhexan-1-ol are deemed appropriate in the risk assessment of bis(2-ethylhexyl) peroxydicarbonate.

Calculated QSAR results using two different models as well as published data (original reference not available) are available for 2-ethylhexan-1-ol which are used in a weight-of-evidence approach.

The 96-h acute LC50 value of 2-ethylhexan-1-ol for fish was calculated using the ECOSAR model. The LC50 (96 h) for fish (species not specified) is estimated at 16.207 mg/L.

In addition, the 96-h LC50 value of 2-ethylhexan-1-ol for fathead minnow was calculated using the VegaNIC model (version 1.0.4). The predicted value for the LC50 (96 h) for fathead minnow is 23.59 mg/L. The experimental value referenced in the program data base (2-ethylhexan-1-ol is a substance of the training set) is 28.3 mg/L. The experimental value is preferred over the predicted value and therefore the experimental value of the training set will be further considered in the risk assessment.

For 2-ethylhexan-1-ol a test was conducted under GLP according to Directive 84/449/EEC, which is similar to OECD test guideline 203. In this experiment with the golden orfe a LC50 (96 h) of 17.1 mg/L was established. The NOEC (96 h) was determined to be 14 mg/L whereas the LC100 was determined to be 21 mg/L, demonstrating a very steep dose-response relationship.

Experimental data are available for the long-term toxicity of for 2-ethylhexan-1-ol to Daphnia. These data will be relevant for PNECfreshwater derivation. Data on acute fish toxicity are only necessary for classification and labelling of the substance.

The estimated QSAR results are in good agreement with published experimental data. The lowest result for acute fish toxicity is the ECOSAR calculated 96-h LC50 of 16.207 mg/L. This value is even below the lowest reported experimental value of LC50 (96 h) = 17.1 mg/L and can be considered as adequately protective. Considering the steepness of the dose-response relationship demonstrated by experimental data, this value can be considered as a clear worst-case and will therefore be carried forward to the risk assessment.

Conclusion: The lowest QSAR-derived LC50 for fish is considered to be adequate for a regulatory conclusion, since sufficiently conservative. No additional (experimental) information is required to cover the endpoint “acute toxicity to fish”.