Zinc bis[12-hydroxyoctadecanoate]

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:

2002-02-08

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with abridged report

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(vers. 1992)

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Zinc bis[12-hydroxyoctadecanoate]

EC Number:

252-669-5

EC Name:

Zinc bis[12-hydroxyoctadecanoate]

Cas Number:

35674-68-1

Molecular formula:

C18H36O3.1/2Zn

IUPAC Name:

zinc bis(12-hydroxyoctadecanoate)

Test material form:

other: solid

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
not applicable

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): municipal sewage treatment plant (67435 Neustadt Wstr., Germany), aeration tank, sample from 2002-02-06
- Pretreatment: activated sludge was aerated continuously and wash with drinking water and OECD-media
- Concentration of sludge: the dry residue was determined to be 7.28 g suspended solids/L, the concentration for testing was 25 mg solids/L

Duration of test (contact time):

29 d

Initial test substance concentration

Initial conc.:

20 mg/L

Based on:

other: calculated organic carbon content

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium acc. to OECD
- Solubilising agent (type and concentration if used): none
- Test temperature: room temperature (20 +/- 1°C)
- pH: no data
- pH adjusted: no data

- Suspended solids concentration: 25 mg solids/L
- Test vessels: "Woulffe'sche bottles" 5 L volume
- Test volume: 3000 mL each
- Continuous darkness: no data

TEST SYSTEM
- Sample preparation: the org. carbon content was calculated to be 68.7 %
- Culturing apparatus: aeration with clean, moistened CO2-free air during the test
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aeration with clean, moistened CO2-free air for 24 h before testing
- Measuring equipment: IC measurement of the emitted CO2 wit a TOC 5050A;
- 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: discharched air was trapped in 0.25 M NaOH solution (one trap followed by a second one)

SAMPLING
- Sampling frequency: at day 2, 4, 6, 8, 10, 13, 17, 21, 28, and 29 of the study
- Sampling method: for the IC measurement 0.5 or 1 ml solution were sampled from the first of the two NaOH traps; on day 29 both bottles were sampled and the IC results were summed up

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes, without inoculum
- Toxicity control: testsubstance + aniline


STATISTICAL METHODS: according to guideline

Reference substance

Reference substance:

aniline

Results and discussion

Preliminary study:

no data

Test performance:

No unusual observations during test reported.

% Degradation

% Degradation 1

Parameter:

% degradation (CO2 evolution)

Value:

14.5

Sampling time:

4 d

% Degradation 2

Parameter:

% degradation (CO2 evolution)

Value:

53.5

Sampling time:

13 d

Remarks on result:

other: end of 10 d window

% Degradation 3

Parameter:

% degradation (CO2 evolution)

Value:

71.4

Sampling time:

28 d

% Degradation 4

Parameter:

% degradation (CO2 evolution)

Value:

72

Sampling time:

29 d

Details on results:

- The 10 day window begins at day 3 (graphically determined). At day 13 53 % was degraded. At the end of the test 72 % was degraded. Thus, the 60 % pass level within the 10 day window was failed.
- Abiotic degration was 4 %.

- Validity: The test is considered valid, as
- the difference of extremes of replicate values of the removal of the test item at the end of the test is less than 20%,
- the percentage degradation of the reference item has reached the pass level of 60% by day 14,
- the total CO2 production of the blind trial was 25 mg CO2/L (mean value)
- Toxicity: If the total degardation in the toxicity test is below 25 %, the test substance is regared as toxic. In this study the total degradation was 49 % in in the toxicity test. However, since the theoretical degradation (mean value of reference and test approach) is 75%, an inhibition of degradation by the test substance was assumed.

BOD5 / COD results

Results with reference substance:

The reference substance aniline was degraded to 72 % within 10 days.

Any other information on results incl. tables

Table 1: Emitted carbon in mg/L

Day	Blind1	Blind2	Refer.	Test 1	Test 2	abiot.	Toxicity
2	1.50	1.66	1.30	2.64	1.65	1.26	0.84
4	2.42	2.53	10.93	5.81	5.28	1.00	4.66
6	2.06	1.77	12.49	8.10	8.23	0.73	10.24
8	2.64	2.80	15.47	11.66	10.65	0.36	15.22
10	3.02	3.28	17.81	14.07	12.77	0.48	17.64
13	4.26	4.88	20.26	17.16	14.58	1.19	21.67
17	4.28	5.00	21.50	19.55	18.49	0.98	24.20
21	4.34	5.11	21.10	19.51	19.30	1.53	24.77
28	4.11	4.77	21.05	20.04	19.02	0.86	25.93
29	6.25	7.42	22.78	22.56	21.53	0.79	27.07

 

Table 2: Degradation in %

Day	Refer.	Test 1	Test 2	Mean	abiot.	Toxicity
2	-1.4	5.0	0.3	2.7	6.0	-1.8
4	41.5	15.7	13.3	14.5	4.8	5.3
6	52.0	29.1	30.0	29.6	3.5	20.1
8	62.6	42.2	37.7	39.9	1.7	30.2
10	72.0	51.5	45.7	48.6	2.3	35.0
13	77.1	59.4	47.6	53.5	5.7	41.3
17	82.9	70.3	65.8	68.0	4.7	47.2
21	80.5	69.7	69.3	69.5	7.3	48.4
28	81.6	73.6	69.3	71.4	4.1	51.9
29	78.3	74.2	69.8	72.0	3.7	48.9

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

see above, "Detail on results" for details

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

Altogether, 71.4% of zinc-12-hydroxystearate was biodegraded after 28 days as determined in the OECD 301B test with 14.5 % after 4 days and 53.5% after 13 days. Zinc-12-hydroxystearate is readily biodegradable as the 60% level was passed within 28 days but failed the 10 day window criteria.