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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1989.09.01 to 1989.10.05
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study was conducted in accordance with a recognized scientific procedure for biodegradation and is based on OECD 301D and EEC Part C.6 [Degradation-biotic degradation: Closed bottle test].
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
A few minor deviations from the protocol of the closed bottle test were introduced. See "any other information on material and methods incl. tables"
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No surrogate or analogue material was used.
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
Seconday activated sludge was obtained from the RZWI Nieuwgraaf in Duiven (1989.09.13). The RZWI Nieuwgraaf is an activated sludge plant treating predominantly domestic wastewater.
Duration of test (contact time):
28 d
Initial conc.:
2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Test procedure
The closed bottle test was performed according to the EEC/OECD test guidelines. In the closed bottle test, a test compound is added to an aqueous solution of mineral salts and exposed to relatively low numbers of microorganisms under aerobic conditions for a period of 28 days. A few minor deviations from the protocol of the closed bottle test were introduced. See "Any other information on materials and methods incl. tables"

Stock solutions
The sodium acetate vas added to the bottles using stock solution of 1000 mg/litre. For the application of the test substance on silica gel, a stock solution of 1000 mg/litre in dichloromethane vas used.

Deionized water
Deionized water containing no more than 0.01 mg Cu per litre was prepared in an Elgastat water purification system (Elga, Breukelen, The Netherlands).

Test bottles
The test was performed in 280 ml BOD (Biological Oxygen Demand) bottles.

Calculation of the biodegradation
The biodegradation was calculated as the ratio of the biochemical oxygen demand (BOD) to the theoretical oxygen demand (ThOD). The ThOD of the test subtance (pure active ingredient) is 1.92 g O2/g test substance. The BOD of the test substance and sodium acetate were calculated from the oxygen concentrations in the bottles with and without test substance but with silica gel (C,F) and the bottles with and without sodium acetate but without silica gel (B, D), respectively (see Table in "Any other information on materials and methods inc. tables".).
Reference substance:
other: Sodium acetate
Preliminary study:
No preliminary study was performed.
Test performance:
No data
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Details on results:
[1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is not biodegraded in the closed bottle test (See "Overall remarks"), and therefore should not be classified as readily biodegradable. This lack of biodegradation is not due to toxicity of the test compound because the endogenous respiration is not inhibited by [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide. Lack of biodegradation does not mean that [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is recalcitrant in nature. The stringency of the test procedures could account for the recalcitrance of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide in the closed bottle test.
Results with reference substance:
The reference substance, sodium acetate was degraded up to 94% BOD/ThOD after 23 days. See tables in "Overall remarks".

0xygen concentration in the closed bottles

time (days)

Concentration (mg/litre)

A

B

C

D

E

F

0

9.1

9.1

9.1

9.1

9.1

9.1

9.1

9.1

9.1

9.1

9.1

9.1

mean

9.1

9.1

9.1

9.1

9.1

9.1

5

8.8

8.8

8.6

8.5

8.7

8.5

4.4

4.4

8.7

8.6

8.4

8.4

mean

8.8

8.6

8.6

4.4

8.7

8.4

15

8.6

8.7

8.3

8.4

8.3

8.5

3.8

3.7

8.1

7.9

8.0

8.1

mean

8.7

8.4

8.4

3.8

8.0

8.1

28

8.5

8.6

8.2

8.1

8.3

8.3

3.2

3.4

8.1

7.9

8.0

7.9

mean

8.6

8.2

8.3

3.3

8.0

8.0

42

-

-

7.9

8.3

8.0

8.1

-

-

-

-

7.6

7.6

mean

-

8.1

8.1

-

-

7.6

57

-

-

7.8

7.9

7.4

7.8

-

-

-

-

7.2

7.1

mean

-

7.9

7.6

-

-

7.2

84

-

-

8.5

7.9

7.3

7.8

-

-

-

-

7.1

7.0

mean

-

8.2

7.6

-

-

7.1

A - Mineral nutrient solution without test material and without inoculum.

B - Mineral nutrient solution without test materialbut with inoculum.

C - Mineralnutrientsolutionwith testmaterial (2 mg/litre) on silica gel and with inoculum.

D - Mineral nutrient solution with sodium acetate (6.7 mg/litre) and with inoculum.

E - Mineral nutrient solution without test material but with inoculum and silica gel.

F - Minerai nutrient solutionwithout testmaterialbutwith inoculum and evaporated silica gel.

Oxygen consumption in the closed bottle test inthe presence of the test substance and sodium acetate

Time (days)

5

15

23

42

57

84

Test substance

(MgO2/l)

0

0

0

0

0

0

Sodium acetate

(MgO2/l)

4.2

4.6

4.9

-

-

-

Percentages biodegradation of the tested substanceand sodium acetate in the closed bottle test

Time (days)

5

15

23

42

57

84

Test substance

(%BOD/ThOD)

0

0

0

0

0

0

Sodium acetate

(%BOD/ThOD)

81

88

94

-

-

-

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
The validity of the test is shown by the oxygen consumption in the control bottle with sodium acetate and an endogenous respiration of 0,4 mg/litre. The pH of the medium at the end of the test period is 7.5.
Effectively, as the difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20% and as the percentage degradation of the reference compound has reached the pass level (25%) by day 14 the test was considered as valid. Moreover, oxygen depletion in the inoculum blank did not exceed 1.5 mg dissolved oxygen/l after 28 days and the residual concentration of oxygen in the test bottles did not fall below 0.5 mg/l at any time. Consequently, the test was considered as valid.

The maximum level of biodegradation of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was 0 % in 28 days. Therefore, according to these results, [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is not considered as readily biodegradable.
In the test conditions, no inhibitory effect of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide on the micro-organisms of the inoculum was observed.
Executive summary:

The ready biodegradability of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was evaluated in a study performed in accordance with OECD testing guideline 301 D and GLP requirements.

The maximum level of biodegradation was 0 % in 28 days. Therefore, according to these results, [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is not considered as readily biodegradable.

In the test conditions, no inhibitory effect of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide on the micro-organisms of the inoculum was observed. Validity criteria were fulfilled.

[1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is not biodegraded in the closed bottle test, and therefore should not be classified as readily biodegradable. This lack of biodegradation is not due to toxicity of the test compound because the endogenous respiration is not inhibited by [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide. Lack of biodegradation does not mean that [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is recalcitrant in nature. The stringency of the test procedures could account for the recalcitrance of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide in the closed bottle test.

Description of key information

The ready biodegradability of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was evaluated in a study performed in accordance with OECD testing guideline 301 D and GLP requirements.

The maximum level of biodegradation was 0 % in 28 days. Therefore, according to these results, [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is considered as non readily biodegradable.

In the test conditions, no inhibitory effect of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide on the micro-organisms of the inoculum was observed. Validity criteria were fulfilled

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The ready biodegradability of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was evaluated in a study performed in accordance with OECD testing guideline 301 D and GLP requirements.

[1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is not biodegraded in the closed bottle test, and therefore should be classified as non readily biodegradable. This lack of biodegradation is not due to toxicity of the test compound because the endogenous respiration is not inhibited by [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide. Lack of biodegradation does not mean that [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is recalcitrant in nature. The stringency of the test procedures could account for the recalcitrance of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide in the closed bottle test.