Sorbitan, tridocosanoate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

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:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge obtained from site Kurume central sewage treatment center (Kurume-shi, Fukuoka, Japan), receiving predominantly domestic sewage
- Concentration of sludge: 30 mg/L (suspended solids)

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium according to guidelne
- Test temperature: 22±1 °C
- Continuous darkness: yes
- pH: 7.3 - 7.8 (at the end of exposure)
- Other: Test solutions were stirred continuously.

TEST SYSTEM
- Culturing apparatus: Closed system oxygen consumption measuring apparatus (No. CM-067)
- Number of culture flasks/concentration: 2
- Details of trap for CO2 and volatile organics if used: Soda lime No.1 (for absorption of carbon dioxide, Wako Pure Chemical Industries)
SAMPLING
- Sampling frequency: O2 consumption was measured continuously.
- Sampling method: automatic measurement without specific sampling


CONTROL AND BLANK SYSTEM
- Inoculum blank: 1
- Toxicity control: 1
- Reference substance: yes, 2 bottles

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

13

Sampling time:

28 d

Remarks on result:

other: mean of two replicates

Details on results:

The test item was not dissolved, the test solution was colorless.
In the test solution (sludge+ test item+ sodium benzoate) for checking the toxicity of the test item, the percentage biodegradation by BOD was 34% after 14 days. According to the test guideline, the test item can be assumed to be not inhibitory on the activated sludge microorganisms at the applied concentration level of 100 mg/L because the percentage biodegradation was > 25% within 14 days.

Results with reference substance:

99% after 14 days

Table 1: Biodgradation rates

	Sludge + test item
	Vessel No. 1	Vessel No. 2	Average
Percentage biodegradation by BOD after 28 days	22	3	13
Percentage biodegradation by BOD at the end of the 10-day window	22	-	-

Table 2: Validity criteria for OECD 301.

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	19%	yes
Percentage degradation of the reference compound has reached the pass levels by day 14.	99% at day 14	yes
The toxicity control should degrade to at least 25% (based on ThOD or ThCO2) within 14 d.	34%	yes

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Interpretation of results:

under test conditions no biodegradation observed

Description of key information

Not readily biodegradable according to OECD criteria (13% after 28 d, OECD 301F).

Additional information

The available test on the ready biodegradability of the test substance was performed according to OECD Guideline 301 F. The biodegradability of the substance was assessed by following the O2 consumption of non-adapted activated sludge over 28 days. At test termination after 28 days a degradation rate of 13% based on O2 consumption was determined. The toxicity control (test substance + reference substance) achieved 34 % degradation after 14 days. Thus, inhibitory effects of the test substance on activated sludge microorganisms can be excluded. Based on the result the substance is considered not readily biodegradable according to OECD criteria.