Azarbre

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February-March 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Rated as Klimisch 2 since report does not give the details for a reference item and rubber septum were used. Latter are not ideal for fragrance substances due to possible loss from the test system by adsorption which in turn can lead to false negative results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Report date:

1995

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

Deviations:

yes

Remarks:

The study was a modified OECD 301B, similar to today's OECD 310.

Principles of method if other than guideline:

The study was a modified OECD 301B protocol, which is similar to today's OECD 310 test.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Diethyldimethylcyclohex-2-en-1-one

EC Number:

272-462-3

EC Name:

Diethyldimethylcyclohex-2-en-1-one

Cas Number:

68845-36-3

Molecular formula:

C12H20O

IUPAC Name:

2,3-diethyl-4,4-dimethylcyclohex-2-en-1-one

Test material form:

other: liquid

Details on test material:

Please note that the trade name Azarbre is used in this report. Recent analytical data has determined the substance to be a multi-constituent (Reaction mass of 3,5-diethyl-2,5-dimethyl-cyclohex-2-en-1-one and 3,5-diethyl-5,6-dimethylcyclohex-2-en-1-one ). As the chemical manufacturing process has not changed since the report was written, the recent analytical information is relevant to the batch which was tested.

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly industrial, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): the inoculum used was 10% by volume of secondary effluent from an unacclimatised activated sludge plant.
- Laboratory culture: not applicable.
- Method of cultivation: not applicable.
- Storage conditions: no data.
- Storage length: no data.
- Preparation of inoculum for exposure: filtered through a Whatman filter paper (541) to remove coarse particulate matter.
- Pretreatment: The level of dissolved inorganic carbon (DIC) was reduced by sparging the filtered effluent with nitrogen after prior adjustment of the pH to 6.5.
- Concentration of sludge: no data.
- Initial cell/biomass concentration: no data.
- Water filtered: no data.
- Type and size of filter used, if any: no data.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

10 mg/L

Based on:

other: nominal organic carbon, assuming 100% purity of the test compound.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation 1

Parameter followed for biodegradation estimation:

CO2 evolution

Parameter followed for biodegradation estimation 2

Parameter followed for biodegradation estimation:

other: Formation of dissolved inorganic carbon.

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral salts medium, as recommended in the 1988 OECD Ring Test on the harmonisation of ready biodegradability tests with the following deviation: the ferric chloride solution contained 0.25 g not 0.2 g. The EDTA stock solution contained 0.4g as recommended in the 1988 OECD Ring Test and not 0.5g as specified in the draft Ecotoxicology SOP 158 01. The slight difference in composition of the mineral salts medium should have no effect on the results.
- Additional substrate: no data.
- Solubilising agent (type and concentration if used): no data.
- Test temperature: 20 deg C (test temperature range 16 - 23 deg C).
- pH: 6.5.
- pH adjusted: yes
- CEC (meq/100 g): no data.
- Aeration of dilution water: no data.
- Suspended solids concentration: no data.
- Continuous darkness: no data.
- Other:

TEST SYSTEM
- Culturing apparatus: hypovials (160 mL volume).
- Number of culture flasks/concentration: no data.
- Method used to create aerobic conditions: vial filled with air and then sealed. The headspace in each vessel has a volume of 60 ml and, when filled with air, contains approximately 6 times the mass of oxygen required for the complete oxidation of the substance.
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: Ionics 555 Inorganic Carbon Analyser.
- Test performed in closed vessels due to significant volatility of test substance: no data.
- Test performed in open system: no data.
- Details of trap for CO2 and volatile organics if used: no data.

SAMPLING
- Sampling frequency: days 4, 7, 10, 14, 18, 21, 24 and 28.
- Sampling method: at intervals during the 28 day test period a vessel is removed and concentration of carbon dioxide in the headspace gas determined. The seal is then broken and the concentration of inorganic carbon in the test medium is also determined. The total inorganic carbon in the vessel is calculated and corrected by subtracting the total inorganic carbon produced in a control.
- Sterility check if applicable: no data.
- Sample storage before analysis: no data.

CONTROL AND BLANK SYSTEM
- Inoculum blank: the control vessels are identical to the test vessels except for the omission of the test substance.
- Abiotic sterile control: no data.
- Toxicity control: no data.

STATISTICAL METHODS: no data.

Reference substance

Reference substance:

not specified

Results and discussion

Test performance:

The air temperature during the 28 day test period was in the range of 16 - 23°C. The temperature of the liquid medium in the vessels during the 28 day test period was in the range of 18.5 - 25°C.

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

ca. 0

Sampling time:

28 d

Details on results:

Azarbre failed the biodegradation test and consequently could not be classified as readily and ultimately biodegradable on the basis of the results obtained on day numbers 14 - 21.

Any other information on results incl. tables

Percentage biodegradation of Azarbre

Day number   4 7  10  14  18  21  24  28  95% CL  % Biodegradation  3.5  -1.3  -5.3  1.3  -4.0  3.8  -9.1  -0.5  -4.1 to 3.1

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

In a guideline study, to GLP, Azarbre (at 10 mg/L) was not readily biodegradable in activated sludge (ca 0% biodegradation at day 28; 95% CL = -4.1 to 3.1).

Executive summary:

Azarbre was evaluated for ready biodegradability in a study conducted according to OECD TG 301B (CO2 evolution test) and to GLP. Adapted sludge

was used for the inoculum.The change in the total inorganic carbon in the vessel was used to determine the percentage biodegradation. Azarbre (at 10 mg/L initial concentration) underwent minimal biodegradation after 28 days in the test conditions.

In conclusion, in a guideline study, to GLP, Azarbre (at 10 mg/L) showed no evidence of ready biodegradability in activated sludge (ca. 0% biodegradation at day 28; 95% CL = -4.1 to 3.1).