Cyclohexylidenebis[tert-butyl] peroxide

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to read-across justification attached to IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

69 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: lumbriculus variegatus

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

5.1 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: lumbriculus variegatus

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

21 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: lumbriculus variegatus

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

> 1 000 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Reproduction/Mortality/Fertility/ Growth Assessed

Remarks on result:

other: nematodes

Description of key information

Two chronic sediment studies are available with a structural analogue substance:

OECD 225 guideline study is not considered optimal for extremely poorly water soluble substances due to the high pore water concentrations measured and the lack of sediment equilibrium. A more realistic indication of sediment effects is at this time not possible data is considered reliable with this restriction. The partitioning of this substance to sediment was 97 %. Similar adsorbtion to sludge has been demonstrated in a sewage treatment simulation test and hence in reality the test substance is unable to pass the water treatment plant. Meaning that sediment exposure is highly unlikely due to the industrial use of the substance and treated effluent only being released.

 

An ISO 10872 (2010) sediment test with nematodes is also available and no effects to any endpoint were observed up to 1000 mg/kg sediment dw.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:

5.1 mg/kg sediment dw

Additional information

The 28 day EC50 (worst case end point reproduction) based on the Day 0 measured test concentrations was 69 mg/kg, 95 % confidence limits could not be statistically determined from the data. The EC10 has not been reported due to the unsuitability of the data. The No Observed Effect Concentration was 5.1 mg/kg and the Lowest Observed Effect Concentration was 21 mg/kg.

 

Analysis of the sediment on Day 0 of the test showed the measured concentrations to range from 51 % to 91 % of nominal. The 10 and 32 mg/L samples were re-analyzed due to measured concentrations being low compared to nominal, however, similarly low measured concentrations were obtained. Analysis of the overlying water on Day 0 showed measured concentrations to range from less than the limit of quantification, determined to be 0.0058 mg/L, to 0.0076 mg/L. Analysis of the interstitial water on Day 0 of the test showed measured concentrations to range from less than the limit of quantification, determined to be 0.029 mg/L, to 63.7 mg/L.

 

Analysis of the sediment on Day 28 of the test showed the measured concentrations to range from 12 % to 81 % of nominal. Analysis of the overlying water on Day 28 showed the measured concentrations to be less than the limit of quantification. Analysis of the interstitial water on Day 28 of the test showed measured concentrations to range from less than the limit of quantification to 11.7 mg/L.

 

The guideline was followed and the study was conducted in a reliable manner for non difficult substances. However due to the extremely poor solubility of the test chemical in question and the indication of pore water concentrations way in excess of the solubility limit. It appears that the instantaneous spiking of the sediment and short resting period was not sufficient to allow steady state and even distribution in the sediment. Sediment exposure can only ever occur in reality at a maximum of 93 µg/L via water with significantly longer resting periods.

 

Chronic nematode test ISO10872 (2010) shows no effects to any endpoint up to 1000 mg/kg dw.