Octadecanoic acid, C16-18-alkyl esters

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:

22 Oct - 19 Nov 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP-Guideline study with acceptable restrictions (The degradation in one replicate was below the pass level and differed by > 20%. However, the mean biodegradation based on BOD was > 70% (replicate 1: 88.5%; replicate 2: 51.56%; replicate 3: 84.79%). Moreover, the primary degradation measured by HPLC was 83, 74 and 100% in the three test vessels supports the assumption that the substance is readily biodegradable according to the OECD criteria. Therefore, the study is considered to be valid.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Deviations:

yes

Remarks:

pH was not measured at the end of the study

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: Circular on Test Methods of New Chemical Substances (Japan), Biodegradation test

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Docosyl docosanoate

EC Number:

241-646-5

EC Name:

Docosyl docosanoate

Cas Number:

17671-27-1

Molecular formula:

C44H88O2

IUPAC Name:

docosyl docosanoate

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

other: mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment

Details on inoculum:

- Source of inoculum/activated sludge: location: 10 sites (4 sewage plants, 3 rivers, 1 lake and 2 bays) around Japan; Sampling depth: return sludge in sewage plants, surface water and surface soil of foreshore.
- Laboratory culture: Thirty minutes after stopping of aeration, discard about one third of the whole volume of supernatant and add an equal volume of a solution (pH adapted to 7.0 with NaOH) containing 0.1% each of glucose, peptone and pottasium orthophosphate, to the settled material and re-commence aeration. This procedure was repeated once per day.
- Temperature: 25 ± 2 °C
- Storage conditions: observed appearance and general condition of sludge, determined sediments, pH, temperature and dissolved oxygen and observed with a light microscope, if it is normal.
- Storage length: started to use: 15 Oct 1991
- Concentration of sludge: 3900 mg/L

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation 1

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation 2

Parameter followed for biodegradation estimation:

DOC removal

Parameter followed for biodegradation estimation 3

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

TEST CONDITIONS
- Composition of medium: recommended medium in the guideline
- Test temperature: 25 ± 1 °C
- Suspended solids concentration: 30 mg/L

TEST SYSTEM
- Culturing apparatus: closed oxygen consumption measuring machine with 300 mL culture bottle
- Number of culture flasks/concentration: 1 (water + test substance), 3 (sludge + test sub.), 1 (sludge + reference sub.), 1 (sludge)
- Measuring equipment: Coulometer
- Details of trap for CO2 and volatile organics if used: soda lime

SAMPLING
- Sampling frequency: Continuously
- Sterility check if applicable: no

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 1 bottle
- Abiotic sterile control: no
- Toxicity control: no

Reference substance

Reference substance:

aniline

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

75.3

Sampling time:

28 d

% Degradation 2

Parameter:

% degradation (test mat. analysis)

Value:

86

Sampling time:

28 d

Details on results:

No 10-day window required. Substance was readily biodegradable.

BOD5 / COD results

Results with reference substance:

The oxygen consumption for aniline in the above used test system reached 60% and 72% degradation after 7 days and 14 days.

Any other information on results incl. tables

The degradation in one replicate was below the pass level (51.56%). However, the mean biodegradation based on BOD was > 70%. Moreover, the primary degradation measured by HPLC was 83, 74 and 100% in the three test vessels supports the assumption that the substance is readily biodegradable according to the OECD criteria.

Table 1. Result of BOD, DOC and HPLC after 28 days

		water + test sub.	sludge + test sub.			Theoretical Amount
		sample No. 6	sample No. 3	sample No. 4	sample No. 5
BOD (*1)	mg	0.0	85.0	49.5	81.4	96.0
DOC	mg	0.0	1.1	0.5	1.0	24.4
HPLC	mg	30.2	5.0	7.7	0.0	30
	% (*2)	101	17	26	0	-

(*1) (sludge + test sub.) was calculated by subtracting blank values.

(*2) Residue percentage was calculated as followed.

Residue percentage = Residue amount (mg) / Theoretical amount (mg) x 100

Applicant's summary and conclusion

Validity criteria fulfilled:

no

Remarks:

Biodegradation in one replicate differed by more then 20%.

Interpretation of results:

readily biodegradable