tert-butyl α,α-dimethylbenzyl peroxide

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: 1a GLP guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

yes

Remarks:

extended period up to 58 days

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

The inoculum came from the activated sludge of the biological wastewater treatment plant from Abidos (France, 64). The effluent, obtained one day before seeding the flasks, was centrifuged at approximately 20 °C for 10 min at 1000 g; the base was re-suspended in dilution water in order to keep the same concentration. The inoculum was preconditioned (aeration) until the flasks were inoculated. The amount of dry material in the inoculum, determined by desiccation at 105 °C until a constant weight is obtained, was 4.41 g/L.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Details on study design:

Because of a low hydro solubility of the test item, 25 mg of TERT-BUTYL CUMYL PEROXIDE are directly pour in test flask, corresponding to a theoretical O2 mass of 65.3 mg per flask (ThOD 2.612 mg O2/mg). A parent solution of sodium benzoate in the dilution water to 2.5 mg/mL, was used in a proportion of 10 mL for 250 mL of dilution water, i.e. 25 mg, corresponding to a theoretical O2 mass of 41.65 mg perflask (ThOD 1.67 mg O2/mg). In the inhibition monitoring flask, equivalent quantities of test and reference items are introduced. For this flask, the corresponding theoretical mass of O2 is 107 mg per flask. The flasks were installed in the respirometer where the stirring system was started. After a waiting period of approximately 2 hour, which is necessary to reach the thermal equilibrium of the solutions at a temperature of 22 ± 1°C, the aerated inoculum, pr econditioned if required, is added to all the flasks that are then plugged.

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

58 d

Results with reference substance:

The percentage degradation of the reference item reached a level of 90.2 % by 14 days which is above the requested level of 60 %

Validity criteria fulfilled:

yes

Remarks:

see conclusions

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The method was applied with respect to the following criteria:
• The difference of extremes of replicate values of the removal of test chemical at the plateau, at the end of the test, or at the end of the 10-d window, was less than 20 %;
• The percentage degradation of the reference item reached a level of 90.2 % by 14 days which is above the requested level of 60 %;
• The oxygen uptake of the inoculum blank was of about 19.6 mg O2/L in 28 days, which is below 60 mg O2/L;
• The pH value in the test suspension was 7.45 at day 58 which is in the range of 6-8.5;
• In the toxicity control flasks, containing both the reference item and TERT-BUTYL CUMYL PEROXIDE the percentage biodegradation reached 37.8 % after 14 days. Since this value is higher than 25%, the test item is not inhibitory for inoculum.

Executive summary:

The GLP study of the "ready" aerobic biodegradability of TERT-BUTYL CUMYL PEROXIDE using the OECD method 301 F shows that the test item reached a maximum biodegradation level of 0% in 58 days, the TERT-BUTYL CUMYL PEROXIDE is thus not readily biodegradable.

The item did not demonstrate any inhibiting effect on the micro-organisms.

Description of key information

Based on the results of a GLP study performed according to the OECD 301F guideline with an extended period (up to 58 days), TERT-BUTYL CUMYL PEROXIDE is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The GLP study of the "ready" aerobic biodegradability of TERT-BUTYL CUMYL PEROXIDE using the OECD method 301 F shows that this item reached a maximum biodegradation level of 0% in 58 days, the TERT-BUTYL CUMYL PEROXIDE is thus not readily biodegradable.

The item did not demonstrate any inhibiting effect on the micro-organisms.