Benzoic acid, 4-hydroxy-, docosyl ester

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an applicable guideline under GLP-conditions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

docosyl 4-hydroxybenzoate

EC Number:

920-338-0

Cas Number:

109236-76-2

Molecular formula:

C29 H50 O3

IUPAC Name:

docosyl 4-hydroxybenzoate

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Municipal sewage treatment plant, D-31137 Hildesheim.
Activated sludge from the sewage plant at Hildesheim is well suited as it receives predominantly municipal sewage and hardly industrial chemical
waste.
The activated sludge was washed twice with autoclaved tap water. After the second washing the settled sludge was filled up with mineral salts
medium and was maintained in an aerobic condition by aeration for four hours. Thereafter the sludge was homogenized with a blender. The
supernatant was decanted and maintained in an aerobic condition by aeration with C02 free air for 5 days. 10 mL/L were used to initiate
inoculation.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

15 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Study of ready biodegradability over a period of 28 days with a non-adapted activated siudge in order to check the rate of biodegradation in % by determination of evolved C02.

Results and discussion

Preliminary study:

Based on the carbon content a ThCC>2 of 2.85 mg CO2/mg test item was calculated. A test concentration of 15 mg/L, corresponding to a carbon
content of 11.7 mg C/L in the test vessels was selected.

Test performance:

The ready biodegradability of the test item 4-Hydroxybenzoic acid behenylester was determined with a non adapted activated sludge over a test
period of 28 days in the Modified Sturm Test. The study was conducted according to OECD 301 B. The test item was tested at a concentration of
15 mg/L in duplicates, corresponding to a carbon content (TOC) of 11.7 mgC/L in the test vessels. The biodegradation of the test item was followed
by titrimetric analysis of the quantity of C02 produced by the respiration of bacteria. The degradation was stopped on day 28 by acidification of the
test solutions. The last titration was made on day 29, after residual CO2 had been purged from the test solutions over a period of 24 h. The
percentage C02 production was calculated in relation to the theoretical C02 production (ThC02) of the test item. The biodegradation rate was
calculated for each titration time.
To check the activity of the test system, sodium benzoate was used as functional control. The percentage degradation of the functional control
reached the pass level of 60 % after 6 days and achieved 90 % after 14 days.

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

89

Sampling time:

28 d

BOD5 / COD results

Results with reference substance:

To check the activity of the test system, sodium benzoate was used as functional control. The percentage degradation of the functional control reached the pass level of 60 % after 6 days and achieved 90 % after 14 days.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The test item is considered to be biodegradable, but failing the 10-day window. The missing of the 10 day window might be caused by the poor solubility of the substance.