2(3H)-Benzofuranone, 5,7-bis(1,1-dimethylethyl)-3-(4-hydroxy-3,5-

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Read-across to a structural analogue is suggested.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1993

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Remarks:

no GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Source: The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap de Dommel', 's-Hertogenbosch, the Netherlands.
Treatment: The sludge was kept under continuous aeration until further treatment. The concentration of suspended solids was 3.5 g/L in the concentrated sludge. Before use, the sludge was allowed to settle for at least 30 minutes and the liquid decanted for use as inoculum at the amount of 10 ml/L of mineral medium.
Reason for selection: The test has been accepted internationally (EEC, OECD) for determining the 'ready' biodegradability of test substances under aerobic conditions.

Duration of test (contact time):

28 d

Initial conc.:

36.1 mg/L

Based on:

test mat.

Initial conc.:

37.7 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Test duration: 28 days (last C02-measurement on the 29th day
Test vessels: 2 litre all-glass brown coloured bottles
Milli-Q water: Tap-water purified by reverse osmosis and subsequently passed over activated carbon and ion-exchange cartridges (Millipore Corp., Bedford, Mass., USA

Mineral medium: 1 L mineral medium contains: 10 ml of solution (a), 1 ml of solutions (b) to (d) and Milli-Q water.
Barium hydroxide, 0.0125 M: 4 g Ba(0H)2.8H20 per litre Milli-Q water was filtered through filter paper and stored in a sealed vessel to prevent absorption of CO2 from the air.
CO2-free air: A mixture of oxygen (21%) and nitrogen (79%) was led through a bottle, containing 0.5 - 1 litre 0.0125 M Ba(0H)2 solution to trap CO2 which might be present in small amounts. The C02-free air was sparged through the scrubbing solutions at a constant rate.
Test concentration: The test substance was tested in duplicate at 36.1 (A) and 37.7 (B) mg, corresponding to 15 mg TOC/L. The organic carbon content was based on the molecular formula.
pH: 7.4 + 0.2 (measured just before the start of the test)
Temperature: 22 + 2°C (recorded daily during the test period)

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 3 - <= 6

Sampling time:

28 d

Validity criteria fulfilled:

yes

Cross-reference 2

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Activated sludge collected from the sewage treatment plant of CH-4153 Reinach on 29/08/94. The pH after collection was 7.0. The preparation was carried out according to the method described in the guideline.

Duration of test (contact time):

29 d

Initial conc.:

18.2 mg/L

Based on:

test mat.

Initial conc.:

19.9 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Vessels: 2 Liter flasks (dark brown glass) equipped with gas inlet and magnetic stirrer.
Water: The test medium was prepared according to the method described in the guideline.
Air: = 25 ml/min carbon dioxide free air.

CO2 scrubbers : approx 250 ml scrubbers with gas inlet tubes equipped with sintered glass tips containing 200 ml 0.05 N sodium hydroxide. Only one CO2 scrubber was used per test bottle. Theoretically, a solution of 0.05 M NaOH is sufficient to trap at least two times more C02than the maximum ThC02 which can evolve in each test bottle (including CO2 possibly evolved from the bacteria e . g . , endogenous respiration). Moreover, experimentally it was confirmed that no measurable CO2 carry over has ever occurred with the scrubbers used.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

1

Sampling time:

29 d

Validity criteria fulfilled:

yes

Cross-reference 3

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

mixture of sewage, soil and natural water

Details on inoculum:

Sludge was sampled at the following locations. It was then treated according to the MITI guidelines.

Fukogawa city sewage plant (Sapporo-shi Hokkaido)
Fukashiba industry sewage plant (Kashima-gun Ibaragi)
Nakahama city sewage plant (Osaka-shi Osaka)
Ochiai city sewage plant (Shinjuku-ku Tokyo)
Kitakami river (Ishinomaki-shi Miyagi)
Shinano river (Nishikanbara-gim Niigata)
Yoshino river (Tokushima-shi Tokushima)
Lake Biwa (Otsu-shi Shiga)
Hiroshima bay (Hiroshima-shi Hiroshima)
Dookai bay (Kitakyushu-shi Fukuoka)

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation:

test mat. analysis

Remarks:

by GC analysis

Details on study design:

Preparation of the standard solution:
Preparation of standard solution to calculate the concentration of the test substance in the sample solutions were as follows. 100 mg of the test substance which precisely weighed was dissolved in ethyl acetate to obtain 1000 mg/L of a standard stock solution. 200 mg/L of a working standard solution was then prepared by diluting it with ethyl acetate.
Preparation of the calibration curve:
100, 200 and 400 mg/L of standard solutions were prepared by the same method mentioned above. These solutions were analyzed according to the analytical conditions described above. A calibration curve was drawn from the relation between the peak area on the chromatograms and the respective concentrations.

Reference substance:

aniline

Key result

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

28 d

Key result

Parameter:

% degradation (test mat. analysis)

Value:

6

Sampling time:

28 d

Details on results:

Under the present test conditions, the test substance was not biodegraded by microorganisms.

Validity criteria fulfilled:

yes

Materials and methods

Test material

Test material information

Constituent 1

Reference substance name:

Reaction product of: 3-hydroxy-5,7-di-tert-butylbenzofuran-2-one with o-xylene

EC Number:

417-100-9

EC Name:

Reaction product of: 3-hydroxy-5,7-di-tert-butylbenzofuran-2-one with o-xylene

Cas Number:

181314-48-7

Results and discussion

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

28 d

% Degradation 2

Key result

Parameter:

% degradation (test mat. analysis)

Value:

6

Sampling time:

28 d

% Degradation 3

Key result

Parameter:

% degradation (CO2 evolution)

Value:

1

Sampling time:

29 d

% Degradation 4

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 3 - <= 6

Sampling time:

28 d

Details on results:

The test substance is regarded as not biodegradable by OECD criteria.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable