Retinyl acetate

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:

1992-09-03 to 1993-01-07

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test carried out under GLP and according to guideline 301B. Some deviations of guideline, but these are not essential for reliability.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

volume of test solution was reduced from 3 to 1.5 L. The formed CO2 was absorbed with NaOH and determined on a carbon analyzer. Due to poor solubility of the substance in water, an emulsifier was used.

Principles of method if other than guideline:

not relevant

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Retinyl acetate

EC Number:

204-844-2

EC Name:

Retinyl acetate

Cas Number:

127-47-9

Molecular formula:

C22H32O2

IUPAC Name:

(2E,4E,6E,8E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-1-en-1-yl)nona-2,4,6,8-tetraen-1-yl acetate

Details on test material:

- Name of test material (as cited in study report): Vitamin A-Acetat
- Physical state: yellow solid
- Radiochemical purity (if radiolabelling): not relevant
- Storage condition of test material: room temperature, in dark
- Other:

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not relevant

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): sewage treatment plant CH-4153 Reinach dd
1992-08-07
- pH after collection was 7.6

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

10.3 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

20.9 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: 1200 ml mineral solution with the inoculum and 15 ml with solubilising agent and test substance
- Solubilising agent (type and concentration if used): 15 ml polyoxyehtylen-Sorbitan-Monooleate (TWEEN 80), 300 mg/L water
- Test temperature: 22 ± 2 degrees C
- Aeration of dilution water:ca 25 ml air/min purified from carbon dioxide
- Continuous darkness: yes, test carried out in dark brown flasks


TEST SYSTEM
- Culturing apparatus: test vessels containing 1.5 L of medium
- Number of culture flasks/concentration: 2 for the blank and the reference substance, one for each of the two test substance concentrations
- Measuring equipment: Carbon analyzer


SAMPLING
- Sampling frequency: every 3-4 days until 28 days
- Sampling method: CO2 traps filled with 200 ml 0.05 N NaOH



CONTROL AND BLANK SYSTEM
- Inoculum blank: water with inoculum containing 15 ml of TWEEN 80 solution
- Other: Inoculum control with aniline as reference substance

Reference substance

Reference substance:

aniline

Remarks:

20 mg/L

Results and discussion

Preliminary study:

no data

Test performance:

not relevant: no unusual observations

% Degradation

% Degradation 1

Parameter:

% degradation (CO2 evolution)

Value:

18.5

Sampling time:

28 d

Remarks on result:

other: 10.3 mg/L

% Degradation 2

Parameter:

% degradation (CO2 evolution)

Value:

42.2

Sampling time:

28 d

Remarks on result:

other: 20.9 mg/L

Details on results:

calculated biodegradation after 28 days:
inoculum with 10.3 mg/L: 15%
inoculum with 20.9 mg/L: 33%

BOD5 / COD results

Results with reference substance:

CO2 evolution after 28 days: 88.9 and 84.2 mg,
Calculated biodegradation after 28 days: 91 and 85% (mean 88&%), meets 10d-window

Any other information on results incl. tables

measured values on 27th day are not reliable due to instrumental defect and are not taken for calculations

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

The validity criteria (reproducibility within 5%) can only be checked in reference test. Is OK.

Interpretation of results:

other: not readily biodegradable under the conditions of the test

Conclusions:

Biodegradation curve shows steady increase of degradation indicating diffusion limitation due to poor water solubility.
Biodegradation after 28 days is 15 and 33% for concentration of 10.3 and 20.9 mg/L respectively. Substance is not readily biodegradable under the conditions of this test.

Executive summary:

Determination of the biodegradability by measurement of the CO2 formation in % of ThCO2 (Theoretical CO2) calculated from the ThOC (Theoretical organic carbon) according to OECD guideline 301B. In comparison to guideline, the volume of test solution was reduced from 3 to 1.5 L, the formed CO2 was absorbed with NaOH and determined on a carbon analyzer. Due to poor solubility of the substance in water, an emulsifier was used. An inoculum of a sewage treatment plant was used. The biodegradation calculated as % of measured amount of CO2 over the theory after 28 days was 15% for the 10.3 mg test substance/L and 33% for the 20.9 mg test substance/L. The biodegradation curve shows a steady increase of degradation indicating diffusion limitation due to poor water solubility. The validity criteria were met. The test substance is not readily biodegradable under the conditions of this test.