Cyclohexylidenebis[tert-butyl] peroxide

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: 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

Duration:

28 d

Dose descriptor:

LC50

Effect conc.:

224 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Remarks on result:

other: There was not a sufficient dose-response relationship to provide a reliable estimate and this value should be used with caution.

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

95.3 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Remarks on result:

other: The 7.5% mortality (p 0.035*) recorded at 16.3 mg a.i./kg dry soil is not considered to be biologically significant as it is an outlying result.

Duration:

28 d

Dose descriptor:

LC50

Effect conc.:

141 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: body weight

Remarks on result:

other: The confidence interval was 96.0 – 207.1 mg a.i./kg dry soil.

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

95.3 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: body weight

Duration:

56 d

Dose descriptor:

LC50

Effect conc.:

95.6 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Remarks:

number of juveniles

Remarks on result:

other: There was not a sufficient dose-response relationship to provide a reliable estimate and this value should be used with caution.

Duration:

56 d

Dose descriptor:

NOEC

Effect conc.:

52.9 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Remarks:

number of juveniles

Remarks on result:

other: The significant decrease observed at 16.3 mg a.i./kg dry soil is not considered of biological significance as it can be considered a result of the low level of adult mortality recorded at this rate.

Description of key information

Earthworm reprodcution test (OECD 222) with a structural analogue substance revealed a NOEC = 52.9 mg/kg soil dw.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil macroorganisms:

52.9 mg/kg soil dw

Additional information

OECD 222 with CAS 6731 -36 -8

An earthworm reproduction study according to OECD 222 with a structural analogue substance (CAS 6731 -36 -8) is available. Adult mortality of 0, 0, 7.5, 5, 2.5, 2.5, 10, 95, 100 and 100% was recorded at rates of 5.04, 9.07, 16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6 and 1000 mg a.i./kg dry soil respectively.  No mortality was recorded in the water or solvent controls. The 16.3, 171.5, 308.6, 555.6 and 1000 mg a.i./kg dry soil Trigonox 29 treated groups had significantly higher mortality than the solvent control group.  The 5 mg a.i./kg dry soil Mascot Systemic treated group had significantly higher mortality than the water control group (p<0.001). The LC50 for the mortality on Day 28 was 224 mg a.i./kg dry soil.  However, there was not a sufficient dose-response relationship to provide a reliable estimate and this value should be used with caution. The NOEC for mortality on Day 28 was 95.3 mg a.i./kg dry soil.  The 7.5% mortality (p 0.035*) recorded at 16.3 mg a.i./kg dry soil is not considered to be biologically significant as it is an outlying result. The Trigonox 29 treated groups at 555.6 and 1000 mg a.i./kg dry soil were excluded from the analysis of body weight for adult earthworms as there were no surviving earthworms on Day 28. The 171.5 and 308.6 mg a.i./kg dry soil Trigonox 29 treated groups had significantly lower adult bodyweight than the solvent control group (p<0.001).  The 5 mg a.i./kg dry soil Mascot Systemic treated group had significantly lower adult bodyweight than the water control group (p<0.001).

The LC50 for the mean body weight of the adult earthworms at Day 28 was 141.0 mg a.i/kg dry soil. The confidence interval was 96.0 – 207.1 mg a.i./kg dry soil.

The NOEC for the mean bodyweight at Day 28 was 95.3 mg a.i./kg dry soil. The Trigonox 29 treated groups at 308.5, 555.6 and 1000 mg a.i./kg dry soil  and the positive control group  were excluded from the analysis of number of juveniles on Day 56 as there were only two surviving earthworms at 308.5 mg a.i./kg dry soil and none at 555.6 and 1000 mg a.i./kg dry soil.  No juveniles were produced in the Mascot Systemic treatment.

The coefficient of variation of the number of juveniles in the solvent control group was 4.39%. The 16.3, 95.3 and 171.5 mg a.i./kg dry soil Trigonox 29 treated groups had significantly fewer juveniles than the solvent control group (p=0.042).  The 29.4 and 52.9 mg a.i./kg dry soil Trigonox 29 treated groups had significantly more juveniles than the solvent control group (p=0.042).  The water control group had significantly fewer juveniles than the solvent control group (p=0.005).

The LC50 for the number of juveniles on Day 56 was 95.6 mg a.i./kg dry soil. However, there was not a sufficient dose-response relationship to provide a reliable estimate and this value should be used with caution.

The NOEC for the number of juvenile worms on Day 56 was 52.9 mg a.i./kg dry soil.  The significant decrease observed at 16.3 mg a.i./kg dry soil is not considered of biological significance as it can be considered a result of the low level of adult mortality recorded at this rate. The study was considered valid as there was ≤ 10% adult mortality at four weeks and ≥30 juveniles had been produced in each water control replicate by the end of the test with the coefficient of variation of reproduction ≤ 30%.  In addition application of the toxic reference Mascot Systemic at 5 mg a.i./kg dry soil resulted in substantial and unequivocal toxic effects.