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Short-term toxicity to aquatic invertebrates

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Description of key information

The 48-h EC50 of bis(4-tert-butylcyclohexyl) peroxydicarbonate to Daphnia magna determined in a study according to OECD 202 is 42 mg/L. 

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
42 mg/L

Additional information

In order to determine the acute toxicity of bis(4-tert-butylcyclohexyl) peroxydicarbonate to Daphnia magna, a study according to OECD guideline 202 was performed using five concentrations ranging from 10000 to 460 mg/L (nominal).

For preparation of test solutions the test item was mixed with dilution water at a nominal loading of 10 g/L, followed by vigorous stirring at 37 ± 2 °C for 7 days. This procedure was chosen to maximise concentrations of the poorly soluble test material. The lower treatments were prepared by diluting with dilution water.

Actual test concentrations (geometric means of 0-hour and 48-hour samples), determined by GC-measurement of the breakdown products cis- and trans-4-tert-butylcyclohexanol, were 8.9, 20.1, 43.1, 97.9, and 208.8 mg/L (aggregate concentrations of parent substance including potentially formed hydrolysis products).

The chemical identity of the dissolved test material being present in test media is unclear. This is due to the fact that the location of decomposition (aqueous test solutions or analytical equipment) cannot be discriminated. Since one additional peak (other than cis- and trans-4-tert-butylcyclohexanol) was detected in the chromatograms, but not identified and quantified, the total concentration of test material is probably higher than the values reported. The effect concentrations determined in this study are therefore conservative.

Daphnia were exposed to the test item for 48 hours in a static test system. The concentration-response curve after 48 hours was very steep, with only one concentration showing intermediate response (70 % immobilisation). None of the animals were immobilised in the control.

The recovery after 48 hours ranged from 96 % to 102 % of the start concentration. Therefore, the aggregate test item concentrations bis(4-tert-butylcyclohexyl) peroxydicarbonate including potentially formed hydrolysis products) can be considered as stable under the test conditions. The determination of the biological results was based on the geometric mean of the measured concentrations.

The 48-h EC50 for bis(4-tert-butylcyclohexyl) peroxydicarbonate, based on geometric mean measured concentrations (sum) of the breakdown products cis- and trans-4-tert-butylcyclohexanol to Daphnia magna is 42 mg/L.