[2-(Isopropoxycarbonyloxy)-benzoyl]-benzoylperoxide

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:

2018-07-07 to 2018-08-06

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted July 17, 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Aerobic activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage treatment plant Rossdorf, Germany.
- Pretreatment: The aerobic activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in test water and centrifuged again. This procedure was done three times. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 3.5 g dry material per litre were mixed with test water and aerated overnight. This suspension was used for the experiment.
- Concentration of sludge: 3.5 g dry material per litre (final sludge concentration in test flasks: 28.7 mg sludge/L)
- Water filtered: Reconstituted water was prepared with pure water

Duration of test (contact time):

28 d

Initial conc.:

103.1 mg/L

Based on:

test mat.

Initial conc.:

112 other: mg O/L

Based on:

ThOD

Remarks:

(1.719 mg O/mg act. ingr.)

Initial conc.:

65 mg/L

Based on:

act. ingr.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
 - Composition of medium: Reconstituted water with activated sludge
 - Additional substrate: no
 - Solubilising agent (type and concentration if used): no
 - Test temperature: 22°C ± 1°C
 - pH: 7.4 (measured at the start of the test), 7.4 (measured at the end of the test)
 - pH adjusted: no
- Aeration of dilution water: no
 - Suspended solids concentration: Stock suspension of 3.5 g/L on dry matter base (final sludge concentration in test flasks: 28.7 mg sludge/L)
 - Continuous darkness: yes
 - Other: The test flasks prepared were incubated at 22°C ± 1°C. The pressure decrease in the reaction vessels was measured over complete experimental phase of 28 days using the BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany. The test flasks were closed gas-tight by a measuring head. Potassium hydroxide solution (45%) was used for trapping the produced carbon dioxide. The amount of O2 consumed by the activated sludge was calculated from the decrease of pressure in the reaction vessel.
 
 TEST SYSTEM
 - Culturing apparatus: BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany; Manometric Test System with test flasks containing a volume of approximately 500 mL.
 - Number of culture flasks/concentration: 7 flasks: 2 test item, 2 Inoculum control, 1 Procedure control, 1 Abiotic control, 1 toxicity control
- Other: The amounts of test item and reference item were directly weighed into the test flasks. No emulsifiers or solvents were used. The closed test flasks were incubated in a climatised chamber under continuous stirring. The consumption of oxygen was determined by measuring the change of pressure in the flasks. Evolved carbon dioxide was absorbed in an aqueous solution (45%) of potassium hydroxide.
 
 SAMPLING
 - Sampling frequency:The change of pressure in the test flasks was measured by means of a manometric method (BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany) each day.
 
 CONTROL AND BLANK SYSTEM
 - Inoculum blank: 2 replicates
 - Abiotic sterile control: 1 replicate
 - Toxicity control: 1 replicate
 - Other: Procedure control – 1 replicate

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

69

Sampling time:

28 d

Details on results:

The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached within a 10-day window; the 10-day window starts when the degradation of the test item reaches at least 10% degradation.
The 10-day window began between day three and four after application, the mean value was calculated to be 13.5% biodegradation (ThODNH4). Therefore, the end of the 10-day window was between day 13 and fourteen. After correction for the mean biochemical oxygen demand of the inoculum controls, the mean biodegradation percentage based on ThODNH4 at the end of the 10-day window was 51%; the criterion of the 10-day window was not passed. The mean biodegradation percentage at the end of the 28-day exposure period was 69% (ThODNH4).

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 81% after 14 days and to 84% after 28 days of incubation. The percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

Validity criteria

Inoculum Control:	The oxygen demand of the inoculum control (medium and inoculum) was 7.5 mg O2/L and thus not greater than 60 mg O2/L within 28 days as required by the test guideline.
pH-Value:	The pH-value of the test item flasks at the end of the test was 7.4 and therefore within the range of pH 6.0 to 8.5 as required by the test guideline.
Reference Item:	The percentage degradation of the reference item should reach the level for ready biodegradability (>60%) within 14 days as required by the test guideline. The reference item sodium benzoate was degraded to more than 60% after 5 days of incubation.
Test Item:	The difference of duplicate values for the degradation of the test item at the end of the 10-day window was less than 20%. The difference of duplicate values at day 28 differed by 0%. The validity criterion was fulfilled.
Toxicity Control:	If in a toxicity test, containing both the test item and a reference item less than 25% biodegradation (based on total ThOD) occurred within 14 days, the test item can be assumed to be inhibitory. The biodegradation was 46% at day 14; the test item was not inhibitory.

Biodegradation in the Toxicity Control
Percentage Biodegradation:	In the toxicity control containing both, the test item and the reference item sodium benzoate, 46% (ThODNH4) biodegradation was noted within 14 days and 59% (ThODNH4) biodegradation after 28 days of incubation. The results are presented inTable2toTable3andFigure1.
Conclusion:	According to the test guidelines the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.
Abiotic Control
Oxygen Demand:	The oxygen demand in the abiotic control was 0 mg/L during the test duration (see Table 2). There was no need to correct the degradation of the test item and toxicity control.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The degradation rate of [2-(Isopropoxycarbonyloxy)benzoyl] benzoylperoxide reached 69% after 28 days but failing the 10-d window.
Therefore, [2-(Isopropoxycarbonyloxy)benzoyl] benzoylperoxide is considered to be readily biodegradable.

Executive summary:

The ready biodegradability of [2-(Isopropoxycarbonyloxy)benzoyl] benzoylperoxide was assessed in a Manometric Respirometry Test according to OECD 301F and under GLP.

The ready biodegradability is evaluated over a period of 28 days. The degradation rate of the test item is calculated by the oxygen consumption of the aerobic activated sludge (non-adapted domestic sewage) microorganisms after 28 days of incubation (103.1 mg/L test item corresponding to 65 mg a.i./L). As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

The mean biodegradation of 10% of the test item was reached between day three and four (ThOD_NH4). At the end of the 10-day window at day 13 and 14, the mean degradation of the test item was 51% (ThOD_NH4) and therefore the 10-day window criterion was not passed. The mean biodegradation at test end after 28 days was 69% (ThOD_NH4).

Therefore, [2-(Isopropoxycarbonyloxy)benzoyl] benzoylperoxide is considered to be readily biodegradable but failing the 10 -d window based on ThOD_NH4.

The reference item sodium benzoate was sufficiently degraded to 81% after 14 days and to 84% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

In the toxicity control containing both, the test item and the reference item sodium benzoate, 46% (ThOD_NH4) biodegradation was noted within 14 days and 59% (ThOD_NH4) biodegradation after 28 days of incubation. According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

Description of key information

The ready biodegradability of [2-(Isopropoxycarbonyloxy)benzoyl] benzoylperoxide was assessed in a Manometric Respirometry Test according to OECD 301F and under GLP.

The degradation rate of [2-(Isopropoxycarbonyloxy)benzoyl] benzoylperoxide reached 69 % after 28 days, but was failing the 10 -d window criterion.

Therefore, [2-(Isopropoxycarbonyloxy)benzoyl] benzoylperoxide is considered to be readily biodegradable, failing the 10 -d window criterion.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window

Type of water:

freshwater