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Short-term toxicity to aquatic invertebrates

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Description of key information

The 48-h EC50 of Rosamusk is 3.8 mg/L based on a read across from CP Formate, which was tested in a study in accordance with OECD TG 202 with an obtained 48-h EC50 of 7.7 mg/L. Rosamusk aquatic invertebrate toxicity is converted from the CP Formate EC50 based on the difference between the measured log Kow values of 4.9 and 4, respectively, and the MW of 196 and 184 g/mol, respectively.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
3.8 mg/L

Additional information

No experimental data is available for Rosamusk. Therefore read-across is performed to the close structural analogue CP Formate. The full read across is presented in the Aquatic Endpoint summary including the read across justification.

CP Formate's acute Daphnia toxicity:

An OECD TG 202 guideline study in compliance with GLP with aquatic invertebrates (Daphnia magna) is available for the test substance. Daphnids (20/concentration) were exposed to WAFs prepared at loading rates of 4.6, 10, 22, 46 and 100 mg/L under static conditions for 48 hours. Exposure was performed in vessels closed with a screw cap and minimal headspace in order to minimize the loss of the test substance due to evaporation. Analysis of the samples taken at the start of the final test showed measured concentrations of 3.19, 7.65, 16.0, 35.1 and 39.4 mg/L in the WAFs prepared at 4.6, 10, 22, 46 and 100 mg/L. During the exposure period the measured concentrations decreased slightly to respectively 2.58, 6.19, 13.9, 28.6 and 28.6 mg/L, i.e. by 13 to 27% below the initial measured concentrations. The average exposure concentrations (t=0 - 48h; geometric mean) were calculated to correspond to 2.9, 6.9, 15, 32 and 34 mg/L. In the control 10% mortality was observed which was within the accepted guideline criterion of ≤10%. At a concentration of 2.9 mg/L no signs of immobility could be detected. First at concentration of 6.9 mg/L, a 25% immobility response was noted which increased to 100% at all higher concentrations. The study met the acceptability criteria prescribed by OECD guideline (202) and was considered valid. Based on these data, the 48-h EC50 value is determined at 7.7 mg/L (95% C.L. is 6.7 -9.5 mg/L).

Rosamusk's acute Daphnia toxicity

Rosamusk has a higher log Kow and a slightly lower water solubility, compared to CP Formate (log Kow is 4.9 and 4.0 and water solubility is 12.6 and 26.1 mg/L, respectively), which can be expected from the additional methyl group in Rosamusk. In view of the difference in log Kow > 0.5 this needs to be accounted for. First the conversion from mg/L to mmol is needed, which then need to be log transformed because the toxicity is related to the log Kow and not to Kow.

The calculation equation is: (Log (x ug/l source / mol weight source)) *(log Kow target / Log Kow source) * (10^)*mol weight target = ug/l target. Conversion from ug/l to mg/l divide the value with 1000 to present the value in mg/l.

The 48-h EC50 of Rosamusk is 3.8mg/L based on a read across from CP Formate, based on the difference between the measured log Kow values of 4.9 and 4, respectively, and the MW of 196 and 184 g/mol, respectively.