Sodium anisate

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:

03 - 31 Aug 2017

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)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Hessisches Ministerium für Umwelt, Klimaschutz, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Aerobic activated sludge from sewage treatment plant Bensheim, Germany
- Storage conditions: aerated
- Storage length: aerated for 2 days
- Preparation of inoculum for exposure: Activated sludge was washed by centrifugation and the supernatant liquid phase was decanted; solid material was resuspended in test water and centrifuged again and repeated three times; based on the the ration of wet sludge to its dry weight calculated aliquots of washed sludge suspension, corresponding to 3.5 g dry material per litre were mixed with test water and aerated for 2 days.
- Pretreatment: An aliquot of sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined.
- Concentration of sludge: 3.5 g dry material per litre

Duration of test (contact time):

28 d

Initial conc.:

102.7 mg/L

Based on:

test mat.

Initial conc.:

160.4 mg/L

Based on:

ThOD

Remarks:

ThODNH4

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: according the OECD guideline 301
- Test temperature: 22 ± 1 °C
- pH: 7.5 to 8.2
- Continuous darkness: yes
- Other: continuous stirring

TEST SYSTEM
- Culturing apparatus and measuring equipment: BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany (Manometric Test System, 500 mL fill volume in flasks)
- Number of culture flasks/concentration: 2
- Details of trap for CO2: potassium hydroxide solution (45%)

SAMPLING
- Sampling method: change of pressure in the test flasks was measured by means of a manometric method

CONTROL AND BLANK SYSTEM
- Inoculum control: 2 replicates
- Abiotic sterile control: 1 replicate (poisoned with HgCl2)
- Toxicity control: 1 replicate
- Other: procedure control - 1 replicate

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

89

Sampling time:

28 d

Details on results:

Test item is not inhibitory to aerobic activated sludge microorganisms since degradation was >25% within 14 days (30% after 14 d and 46% after 28 d).

Results with reference substance:

The reference item was sufficiently degraded to 76% after 14 days and to 79% after 28 days of incubation.

Table 1: Validity criteria

Criterion from the guideline	Outcome	Validity criterion fulfilled
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%.	8%	yes
Percentage degradation of the reference compound has reached the pass levels by day 14.	>60%	yes
The oxygen uptake of the inoculum blank is normally 20-30 mg O2/L and should not be greater than 60 mg/L in 28 days.	12.5 mg/L	yes

Validity criteria fulfilled:

yes

Remarks:

For further information see section "Any other information on results incl tables".

Interpretation of results:

readily biodegradable

Conclusions:

Test item is readily biodegradable and not inhibitory to aerobic activated sludge microorganisms since degradation was >25% within 14 days (30% after 14 d and 46% after 28 d).

Description of key information

Readily biodegradable: 89% within 28 d (OECD 301F)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

One GLP guideline study according to OECD 301F is available investigating the ready biodegradability of sodium anisate (CAS 536 -45 -8). A mixed microbial population of the activated sludge from sewage treatment plant Bensheim, Germany was inoculated with a nominal concentration of 102.7 mg/L test substance and incubated for 28 d under controlled conditions in the dark. Degradation was followed by the determination of dissolved oxygen content each day. An inoculum blank, a reference control and a toxicity control were run in parallel. The derived 28 d degradation rate was 89% for the test substance and 30% for the toxicity control after 14 d. Since the test substance reached the pass level of 60% biodegradation within 28 d it is considered to be readily biodegradable according to the OECD criteria. Due to the fact that the degradation rate of the toxicity control was >25% after 14 d, toxic effects of the test substance to the inoculum can be excluded.