Sulfonic acids, C6-8-alkane, sodium salts

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

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, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Station Epuration Wavre 2nd stage, 26/09/2004
- Concentration of sludge:
- Initial cell/biomass concentration: >10,000,000 CFU/mL
- Water filtered: yes/no
- Type and size of filter used, if any:

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:standard medium used
- Additional substrate: no
- Test temperature: 21.4 - 20.8 deg C
- pH: 7.3 start/7.6 end
- pH adjusted: no
- Aeration of dilution water: yes
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus:3 L flasks mounted with an aeration tube on a magnetic stirrer.
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: CO2-free air passed through test system at 50-100 mL/min.
- Test performed in open system: yes
- Details of trap for CO2 : 100 mL flasks containing Ba(OH)2 solution. Every 2 days the flask closest to the test container is removed and back-titrated against HCl to determine the amount of CO2 released.

SAMPLING
- Sampling frequency: days 0, 2, 4, 7, 9, 11, 14, 16, 18, 21, 23, 25, 28, 29
- Sampling method: CO2 passed through a solution flask containing Ba(OH)2 where it precipitates as Ba(CO3)2. Remaining Ba(OH)2 is back titrated with HCl using phenolphthalein as indicator.

CONTROL AND BLANK SYSTEM
- Inoculum blank:
- Abiotic sterile control: No
- Toxicity control: Toxicity reference susbtance sodium benzoate at 20 mg C/L

STATISTICAL METHODS: None

Reference substance:

benzoic acid, sodium salt

Remarks:

20 mg C/L

Parameter:

% degradation (CO2 evolution)

Value:

6.6

Sampling time:

2 d

Parameter:

% degradation (CO2 evolution)

Value:

27.6

Sampling time:

4 d

Parameter:

% degradation (CO2 evolution)

Value:

60.5

Sampling time:

11 d

Parameter:

% degradation (CO2 evolution)

Value:

75

Sampling time:

28 d

Results with reference substance:

89.7 % degradation in 28-days

Blank control = 22.0 mg

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Executive summary:

The substance is readily biodegradable - 75% degradation after 28 days, meeting 10 -day window (OECD TG 301B).

Description of key information

The substance is readily biodegradable - 75% degradation after 28 days, meeting 10 -day window (OECD TG 301B).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The ready biodegradability of the substance was tested in a study performed according to OECD TG 301B (CO2 evolution test). The substance achieved 75 % degradation after 28 days and reached 60.5 % within the 10 day window after exceeding 10 % degradation. On this basis, the substance is readily biodegradable.