Benzene, C10-13-alkyl derivs.

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 Apr 1995 to 26 May 1995

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)

Qualifier:

according to guideline

Guideline:

other: ISO Guideline No. 9408

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): water treatment plant of Novara Italy
- Storage conditions: aerated at room temperature
- Storage length: collected 24 hrs before use

Duration of test (contact time):

28 d

Initial conc.:

141.9 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

- Test temperature: 22 +/- 0.2 degree C
- Biodegradability is measured by means of manometric respirometry. A measured volume of inoculated medium with a known amount of test substance is stirred in a closed flask. The consumption of oxygen is determined from the reduction in volume of the air contained in the apparatus. Evolved CO2 is adsorbed to soda lime and the amount of oxygen taken up by the substance (corrected for the blank) is expressed as a percentage of the theoretical oxygen demand calculated from the formula of the compound. A reference substance (sodium benzoate) was run in parallel to ensure viability of the inoculum.

Reference substance:

benzoic acid, sodium salt

Test performance:

The reference substance, sodium benzoate, was within the expected range and the study is valid.

Key result

Parameter:

% degradation (O2 consumption)

Value:

64

Sampling time:

28 d

Remarks on result:

other: readily biodegradable, passes 10-day window

Details on results:

Mean degradation at plateau = 78.7%. The test substance was insoluble in water and therefore was added directly to the test flasks by microsyringe.

The test substance was 64.1% degraded at the end of 28 days. The test substance met the 10 -day window and is therefore considered readily biodegradable.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test substance was readily biodegradable.

Executive summary:

The ready biodegradability of the test substance, was determined using the manometric respirometry test. A measured volume of inoculated medium with a known amount of test substance is stirred in a closed flask. The consumption of oxygen is determined from the reduction in volume of the air contained in the apparatus. Evolved CO2 is adsorbed to soda lime and the amount of oxygen taken up by the substance (corrected for the blank) is expressed as a percentage of the theoretical oxygen demand calculated from the formula of the compound.  A reference substance (sodium benzoate) was run in parallel to ensure viability of the inoculum. The test substance was 64.1% degraded at the end of 28 days. The test substance met the 10 -day window and is therefore considered readily biodegradable. In accordance with the OECD Guidelines for Testing of Chemicals Revised Introduction to Section 3 Tests, Item 43, the 10 -day window criterion is not applicable because of the sequential degradation of different components fo the mixture. Therefore, LAB is readily biodegradable.

Reference 2

Endpoint:

biodegradation in water: screening tests

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

standard river die-away method

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water / sediment

Details on inoculum:

- Source of inoculum: Illinois river water or Illinois river sediment
- Pretreatment: water was glass wool filtered

Duration of test (contact time):

42 d

Initial conc.:

100 µg/L

Based on:

test mat.

Initial conc.:

500 µg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

TEST CONDITIONS
- Test temperature: ambient

TEST SYSTEM
- Culturing apparatus: 32 oz Boston round bottles
- Test performed in open system: bottles were loosely capped

SAMPLING
- Sampling frequency: weekly

Parameter:

% degradation (test mat. analysis)

Value:

99

Sampling time:

42 d

Remarks on result:

other: 100 ppb initial concentration

Parameter:

% degradation (test mat. analysis)

Value:

96.3

Sampling time:

42 d

Remarks on result:

other: 500 ppb initial concentration

Details on results:

The half-life of Alkylate 225 was 4 days at 100 ppb and 9 days at 500 ppb. The removal rate varied from 0.076 to 0.170 per day.

Validity criteria fulfilled:

not specified

Interpretation of results:

other: rapidly biodegradable

Conclusions:

The substance rapidly biodegraded in natural river water.

Executive summary:

Concentrations of 100 ppb or 500 ppb were added to samples of 500 ml of natural river water. Concentrations of various substance isomers were determined weekly. Total exposure was 42 days. At the end of this period, the substance was almost completely biodegraded (<96%). The half-life was 4 days for the 100 ppb initial concentration, and 9 days for the 500 ppb initial concentration. This shows that substance degrades more quickly at lower concentrations.

Description of key information

 The substance is readily biodegradable. The ready biodegradation of the substance was determined in an OECD 301F guideline study.  

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The ready biodegradation of the substance was determined in an OECD 301F guideline study (manometric respirometry test). The substance reached 6.1% biodegradation in 28 days and passed the 10 day window. The substance is readily biodegradable.