tert-butyl α,α-dimethylbenzyl peroxide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

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 (OECD 301 F)

Reason / purpose for cross-reference:

reference to same study

Guideline:

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

Deviations:

yes

Remarks:

extended period up to 58 days

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

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.

Test organisms (species):

activated sludge of a predominantly domestic sewage

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.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

56 d

Hardness:

No data

Test temperature:

22 ± 1°C

pH:

No data

Dissolved oxygen:

No data

Salinity:

Not relevant

Nominal and measured concentrations:

Nominal concentration 100 mg/L

Details on test conditions:

This test was performed according to OECD 301F with the following conditions:

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 (positive control):

no

Duration:

58 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

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.

Validity criteria fulfilled:

not applicable

Conclusions:

TERT-BUTYL CUMYL PEROXIDE is not toxic to microorganisms at the 100 mg/L concentration (NOEC = 100 mg/L, nominal concentration).

Executive summary:

The toxicity of TERT-BUTYL CUMYL PEROXIDE to microorganism was estimated in a ready biodegradability study performed according to OECD 301F guideline and GLP requirements.

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 at the 100 mg/L concentration (NOEC = 100 mg/L, nominal concentration).

Description of key information

TERT-BUTYL CUMYL PEROXIDE is not toxic to microorganisms at the 100 mg/L concentration (NOEC = 100 mg/L, nominal concentration).

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

100 mg/L

Additional information

The toxicity of TERT-BUTYL CUMYL PEROXIDE to microorganism was estimated in a ready biodegradability study performed according to OECD 301F guideline and GLP requirements.

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 at the 100 mg/L concentration (NOEC = 100 mg/L, nominal concentration).