12-hydroxystearic acid

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted according to accepted guidelines and GLP

Justification for data waiving:

other:

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Materials and methods

Test guideline

Test guideline 1

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

not applicable

Test guideline 2

Qualifier:

according to guideline

Guideline:

ISO Draft (BOD Test for Insoluble Substances)

Deviations:

not applicable

Principles of method if other than guideline:

The ISO draft (BOD Test for Insoluble Substances) is based on the closed bottle test (OECD Guideline 301D) and the RDA-Blok-test, previously published (Blok J.: "A repetitive die-away (RDA) test combining several biodegradability test procedures". Int. Biodeterior. Bull. 15 (1979):57-63) and ring-tested by the OECD (1988 ring-test on ready biodegradability).

The purpose of the method is the measurement of the aerobic ultimate biodegradability, preferably of poorly soluble organic compounds in an aqueous medium at a test concentration of 100 mg ThoD/L. The extent of degradation is determined as the ratio of the biochemical oxygen demand (BOD) within 28 d to either ThoD or COD.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Castor oil, hydrogenated

EC Number:

232-292-2

EC Name:

Castor oil, hydrogenated

Cas Number:

8001-78-3

IUPAC Name:

8001-78-3

Details on test material:

- Name of test material (as cited in study report): Edanor P 19 or castor oil, hydrogenated

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
None

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): From a sewage treatment plant from Hochdahl predominantly municipal sewage serving for a population equivalent of approximately 27 000.
- Preparation of inoculum for exposure: After addition of a magnetic stirrer the inoculum was stabilised under laboratory conditions for approximately one week.
- Concentration of sludge: 2.5-3.5 mg/L of test medium

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
P = 116 mg/L
N = 1.3 mg/L
Na = 86 mg/L
K = 122 mg/L
Mg = 2.2 mg/L
Ca = 9.9 mg/L
Fe = 0.05-0.01 mg/L
- Test temperature: 20-25 degree C when the bottles were incubated in the shaker. The temperature was adjusted to 20 ± 0.5 degree C half an hour before each oxygen measurment.

TEST SYSTEM
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: The bottles were aerated with compressed air by means of a sintered glass tube until oxygen saturation was reached.
- Measuring equipment:
The COD was determined in a variant of the ISO method 6060 (closed system with a pressure equaliser / Kelkenberg method, Z.f. wasser und abwasserforschung 8, 146, 1975)
The oxygen determination was performed using a oxygen-electrode (WTW; FRG; microprocessor oximeter OXI 2000 with electrode model TriOxmatic EO 200)
- Test performed in closed vessels: Yes
- Other: The bottles were shaking continously to assure steady state oxygen partitioning between liquid and gas

SAMPLING
- Sampling frequency: Weekly

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

7 d

Remarks on result:

other: None

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

28

Sampling time:

14 d

Remarks on result:

other: None

% Degradation 3

Parameter:

% degradation (O2 consumption)

Value:

54

Sampling time:

21 d

Remarks on result:

other: None

% Degradation 4

Parameter:

% degradation (O2 consumption)

Value:

64

Sampling time:

28 d

Remarks on result:

other: None

Details on results:

For further details on the result, see Tables 1 and 2 and Figure 1 under "attached background material"

BOD5 / COD results

BOD5 / COD

Parameter:

COD

Value:

2 440 mg O2/g test mat.

Results with reference substance:

Degradation (calculation based on ThoD):
7 d: 82 %
14 d: 92 %
21 d: 94 %
28: d 95 %

Any other information on results incl. tables

None

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

other: Ultimately biodegradable

Conclusions:

Under the test conditions, 64 % of castor oil, hydrogenated was degraded within the 28 d test period. The substance could therefore be considered as ultimately biodegradable.

Executive summary:

The ultimate biodegradability of the test substance was tested in a 28 d two phase closed bottle test (OECD guideline 301 D) / BODIS-test with GLP compliance. The test represents a modification of the closed bottle test especially suited for poorly soluble compounds.

A defined mineral medium was inoculated with a mixed bacterial inoculum, stabilized under laboratory conditions for 1 week and then spiked with a predetermined amount of test substance. The test vessels were glass bottles with a known volume of aqueous test mixture (2/3) and air (1/3). The bottles were shaken continuously to assure steady state oxygen partitioning between liquid and gas phase. The degradation was followed by weekly measurements of the BOD in the aqueous phase for a 28 d period. One blank control and one reference substance, sodium acetate, were run in parallel for validity purposes. The total oxygen uptake in the flasks was calculated from the measured dissolved oxygen concentration divided by the saturation value at normal conditions and multiplied with the total oxygen content.

Under the test conditions, 64 % of the test substance was degraded within the 28 d test period. The substance could therfore be considered as ultimately biodegradable.