Isotridecanol, ethoxylated

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Please refer to the Analogue Approach Justification provided in Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

equivalent or similar to guideline

Guideline:

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

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

not specified

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): Denton Wastewater Treatment Plant, Denton, Maryland, USA
- Pretreatment: The sludge was sieved using a 2-mm screen and then aerated for approximately four hours. After the aeration period, the sludge was homogenized in a blender at medium speed for approximately two minutes and then allowed to settle for approximately 30 minutes.
- Concentration of sludge:
- Initial cell/biomass concentration:

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: 2470 mL of NANO®pure water, 3 mL calcium chloride solution (2.75%), 3mL of ferric chloride solution (0.025%), 3 mL of magnesium sulfate solution (2.25%), 30 mL of phosphate buffer (pH 7.4), 30 mL of the activated sludge inoculum
- Test temperature: 18.6 to 21.8°C
- pH: 7.2
- pH adjusted: no

TEST SYSTEM
- Culturing apparatus: amber 4-liter bottles
- Number of culture flasks/concentration: 2
- Details of trap for CO2 and volatile organics if used: 100 mL of 0.5 N KOH


SAMPLING
- Sampling frequency: CO2 traps were removed for analysis on days 1, 6, 8, 13, 15, 19, 22 and 26.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates
- Reference control: 2 replicates

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

50.7

Sampling time:

28 d

Remarks on result:

other: mean of two replicates

Results with reference substance:

Biodegradation rate: 92.5 % after 28 days, 78.3% after 15 days

Table 1: Ultimate biodegradation after x days [% of ThCO2]

	Cumulative Percent of Theoretical Carbon Dioxide Evolved1
Day	Reference 1	Reference 2	Test substance	Test substance
1	0.0	-0.2	-0.1	0.4
6	56.4	52.5	10.0	9.9
8	64.6	62.9	13.6	13.2
13	71.0	78.1	25.8	24.0
15	75.3	81.3	30.6	29.7
19	79.3	39.1	38.3	37.8
22	84.7	88.6	41.8	41.1
26	87.4	89.8	45.3	46.0
29	91.3	93.6	51.6	49.7
Mean	92.5		50.7

Table 2: Validity criteria for OECD 30 B1.

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%.	< 5%	yes
Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).	78.3% after 15 days	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	n.a.	n.a.
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	0	yes
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium.	5.2 mg/L

Validity criteria fulfilled:

yes

Remarks:

please refer to "Any other information on results incl. tables"

Interpretation of results:

not readily biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

supporting study

Study period:

12 Jan - 10 Feb 2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Please refer to the Analogue Approach Justification provided in Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

no

Remarks:

The test facility is certified according to GLP, the performance of the study occurred under GLP-near conditions without the formal procedure of GLP quality assurance.

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): Activated sludge from the municipal wastewater treatment plant Breisgauer Bucht, Germany treating predominantly domestic wastewater
- Pretreatment: The activated sludge was washed twice by settling the sludge, decanting the supernatant and resuspending the sludge in aerated tap water
- Concentration of sludge: 30 mg solids/L

Duration of test (contact time):

28 d

Initial conc.:

20 - 20.1 mg/L

Based on:

other: TOC

Initial conc.:

43.5 - 43.6 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: acc. to guideline
- Test temperature: 21.0 - 21.5 QC
- Suspended solids concentration: 30 mg/L dry solids
- Continuous darkness: diffuse light

TEST SYSTEM
- Culturing apparatus: Gas wash bottles (2000 ml volume) with lateral connecting pieces for butyl rubber septums were used as reactors. The CO2 produced in the reactors was absorbed in two 250 ml gas wash bottles in series.
- Number of culture flasks/concentration: 3
- Details of trap for CO2 and volatile organics if used: 0.2 M NaOH

SAMPLING
- Sampling frequency: on days 0, 4, 7, 11, 14, 21, and 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 replicates
- Toxicity control: 1 replicate

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

60.2

Sampling time:

28 d

Remarks on result:

other: mean of three replicates

Details on results:

The degradation in the toxicity control was 68.6% within 14 days and 76.1% within 28 days

Results with reference substance:

Biodegradation rate after 14 d: 97,43 (mean of three replicates)

Table 1: Ultimate biodegradation after x days [% of ThCO2]

Flask	Day
	0	4	7	11	14	21	28	28 (after acidification)
Test 1	0	18.3	33.5	46.0	51.0	61.6	67.7	66.5
Test 2	0	17.0	29.8	40.5	51.3	56.4	59.7	55.5
Test 3	0	17.2	32.5	42.0	49.6	53.9	57.8	58.7
Reference 1	0	79.4	90.6	93.4	93.3	100.6	98.3	97.3
Reference 2	0	79.1	92.8	100.1	100.9	108.8	105.6	106.1
Reference 3	0	83.1	98.1	96.1	98.1	108.9	105.4	107.9
Toxicity control	0	41.2	55.3	65.6	68.6	74.0	74.7	76.1

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%.	<10%	yes
Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).	>90%	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	68.6%	yes
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	0	yes
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium.	29.5 mg/L	yes

Validity criteria fulfilled:

yes

Remarks:

please refer to "Any other information results incl. tables"

Interpretation of results:

readily biodegradable, but failing 10-day window

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Study period:

03 Mar - 31 Mar 1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Please refer to the Analogue Approach Justification provided in Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

equivalent or similar to guideline

Guideline:

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

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

not specified

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): Activated sludge from the aeration tank of a municipal waste water treatment plant (ARA Werdhölzli, Zürich), not adapted, not pre-conditioned
- Concentration of sludge: 30 mg/I of suspended solids

Duration of test (contact time):

28 d

Initial conc.:

18.5 - 18.7 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Aerobic mineral salts medium prepared with deionised water
- Test temperature: 22±0.5 DC
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes, temperature-controlled dark room

TEST SYSTEM
- Culturing apparatus: 2500 ml closed glass bottle containing a total volume of test solution of 2000 ml;
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aerated with CO2-free air
- Measuring equipment: gas-absorption bottles containing 125 ml of 0.15 M NaOH
- Details of trap for CO2 and volatile organics if used: NaOH

SAMPLING
- Sampling frequency: daily

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates
- Procedure control: 1 replicate
- Abiotic sterile control: no
- Toxicity control: no

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

75

Sampling time:

28 d

Parameter:

% degradation (DOC removal)

Value:

82

Sampling time:

28 d

Results with reference substance:

The reference substance reached 97% after 14 days.

Table 1: Validity criteria for OECD 301 B

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%.	<5%	yes
Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).	97%	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	n.a.	n.a.
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	0	yes
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium.	18.5 mg/L	yes

Table 2 CO2 produced by the test units, the inoculum blank and the procedure control

	Inoculum blank	Procedure control blank * (sodium benzoate)		Test unit 1		Test unit 2
Time (days	Total CO, release in test sample [mgIC/I]	Total CO, release in test sample [mgIC/I]	Degradation [%]	Total CO, release in test sample [mgIC/I]	Degradation [%]	Total CO, release in test sample [mgIC/I]	Degradation [%]	Mean Degradation [%] Test unit 1+2
0	0	0	0	0	0	0	0	0
1	0.3	6.5	33.2	-0.3	-3.2	0	-1.6	-2.4
2	1.9	12.3	55.6	1.9	0.0	2.2	1.6	0.8
5	6.3	21.2	79.7	9.5	17.1	10.8	24.3	20.7
8	8.3	26.0	94.7	14.9	35.4	14.2	31.6	33.6
12	10.5	28.6	96.8	21.0	56.3	20.6	54.5	55.4
16	12.0	30.2	97.4	24.9	69.1	24.4	66.9	68.0
19	13.6	31.9	97.9	27.5	74.5	27.0	72.3	73.4
22	14.4	32.7	97.9	28.5	75.5	28.1	73.9	74.7
26	17.0	35.4	98.4	31.3	76.6	31.0	75.5	76.1
28	18.5	36.9	98.4	32.5	75.0	32.5	75.5	75.3

Validity criteria fulfilled:

yes

Remarks:

Please refer to "Any other information on results incl tables"

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable: 75% (CO2 evolution) in 28 days (OECD 301B)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Studies investigating the ready biodegradability of Isotridecanol, ethoxylated, < 2.5 EO (CAS 69011-36-5) are not available. The assessment is therefore based on tests available for the structural analogue Isotridecanol, ethoxylated, 3 EO (CAS 24938-91-8). Three studies conducted according to OECD guideline 301B, conducted with domestic activated sludge as inoculum, are available.

In the key study, a degradation rate of 75% based on CO2 evolution was determined. Based on DOC removal a degradation rate of 82% was recorded after 28 days of incubation (OECD 301B, 1999). Based on the results the substance is readily biodegradable. In a supporting study, a degradation rate of 60.2 mg/L based on CO2 evolution was determined. The test substance can be considered as readily biodegradable but failing the 10-day window (OECD 301B, 2006). In a third study conducted according to OECD 301 B a degradation rate of 50.7% was determined (OECD 301b, 2005).

Based on the results for the read-across substance, Isotridecanol, ethoxylated, < 2.5 EO (CAS 69011-36-5) is considered readily biodegradable according to OECD criteria.