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Short-term toxicity to aquatic invertebrates

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Description of key information

The 48-hour EC50 of bis(2-ethylhexyl) peroxydicarbonate to Daphnia magna was 9.4 mg/L (EU C.2, OECD 202).

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
9.4 mg/L

Additional information

The 48-hr acute toxicity of bis(2-ethylhexyl) peroxydicarbonate (75.3 % in isododecane) to Daphnia magna was studied under static conditions according to method EU C.2 and OECD 202. Daphnids were exposed to nominal concentrations of 0, 9.9, 14.8, 22.2, 33.3, and 50 mg/L for 48 hours. The test item is a mixture of 2 constituents with different solubilities and physico­chemical properties. Test solutions were prepared according to the WAF methodology (water accommodated fraction). Mortality/immobilisation was observed daily.

Concentrations of the test item were measured by gas chromatography coupled with mass spectrometry. The parent substance was quantified via its degradation product 2-ethyl hexanol. The final concentrations of bis(2-ethylhexyl) peroxydicarbonate were not all maintained within the designated limit of 80 % of initial. Thus effective concentrations were calculated using geometric means of final and initial measured concentrations of the test item.The 48-hour EC50was 9.4 mg/L.

This study is considered as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

 

Results synopsis

EC50 (24 h) and EC50 (48 h) values are summarized in the following table:

Effective concentration (mg/l)

Value

95 % CI

EC50 (24 h)

32

ND

EC50 (48 h)

9.4

ND

CI=confidence interval; ND=not determined

 

Please note: The test was done according to the WAF procedure (since the test item contains 25 % isododecane). Measurements were made for the degradation product 2-ethylhexanol by GC-MS. Isododecane is stated to be practically insoluble in water (no exact values available). The water solubility of the degradation product 2-ethyl hexanol is much higher compared to isododecane. However, isododecane may contribute to the overall toxicity observed in the test. Therefore, the test can be regarded as a worst-case that can be used in the assessment of the pure substance (which is, however, not stable without the additive).