Poly(oxy-1,2-ethanediyl), α-(carboxymethyl)-ω-hydroxy-, C16-18 (even numbered) and C18-unsatd. alkyl ethers

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

7 June - 17 August 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): sewage plant at Taunusstein-Bleidenstadt

Prior to use a sampie was washed twice with mineral nutrient solution of the CO2 -Evolution-Test to eliminate organic components and carbonates from the sludge. After resolution with mineral nutrient medium the sludge was aerated by means of compressed humidified alr for about four hours, Before use as inoculum for the COrEvolution-Test the sludge was homogenised in a "Waring Blender" at low speed for 2 minutes and then filtered through a cotton filter previously carefully rinsed with deionised water. The filtrate was used as inoculum (1 % of the final volume of the test solution) on the same day of preparation.

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

- Total volume: 3500 mL; 35 mL of the inoculum
- t0: 84.6 mg (first test solution) and 83.8 mg (second test solution)
- Final (calculated) concentration in the test solution: 10 mg C/L
- Two test solution for blank correction
- One test solution containing 120.1 mg sodiumbenzoate/3.5L (20mg C/L) of test solution was run in parallel.
- One test solution was prepared using 120.4 mg sodium benzoate and 84.8 mg of the test item for toxicity control.

Reference substance:

benzoic acid, sodium salt

Parameter:

other: ThCO2

Value:

82

Remarks on result:

other: mean

Parameter:

other: ThCO2

Value:

73

Sampling time:

28 d

Remarks on result:

other: 84.6 mg test item

Parameter:

other: ThCO2

Value:

90

Sampling time:

28 d

Remarks on result:

other: 83.8 mg test item

Results with reference substance:

The reference item sodium benzoate was degraded by 84%, the "10-days-window" being met within 9 days (72% degradation).

Concentration: 84.6 mg/3.5L/ ≈16 mg TOC [1]/L

ThCO2 [2]: 2491 mg CO2/g test item

1st Test Solution with 16 mg C/L

Date	Time (d)	mg CO2 generated in the test solution, cumulative	%TCO2 (=%Biodegradation)
06 -10 -05	2	4.92	2
06 -13 -05	5	54.53	26
06 -17 -05	9	105.94	50
06 -24 -05	16	150.04	71
06 -29 -05	21	153.78	73
07 -06 -05	28	154.34	73 [4]
07 -07 -05	29	154.37	73 [5]

Concentration: 83.8 mg/3.5L/≈16 mg TOC [1]/L

ThCO2 [2]: 2491 mg CO2/g test item

2nd Test Solution with 16 mg C/L

Date	Time (d)	mg CO2 generated in the test solution, cumulative	%TCO2 (=%Biodegradation)
06 -10 -05	2	4.84	2
06 -13 -05	5	57.50	28
06 -17 -05	9	112.99	54
06 -24 -05	16	163.47	78
06 -29 -05	21	174.01	83
07 -06 -05	28	183.26	88 [4]
07 -07 -05	29	188.71	90 [5]

Concentration: 120.1 mg/3.5L/≈20 mg TOC [1]/L

ThCO2 [2]: 2131 mg CO2/g control item

3nd Test Solution with 20 mg C/L Sodiumbenzoate

Date	Time (d)	mg CO2 generated in the test solution, cumulative	%TCO2 (=%Biodegradation)
06 -10 -05	2	80.15	31
06 -13 -05	5	149.82	59
06 -17 -05	9	184.40	72
06 -24 -05	16	213.61	83
06 -29 -05	21	215.51	84
07 -06 -05	28	217.07	85 [4]
07 -07 -05	29	215.97	84 [5]

Concentration of test item: 84.8 mg/3.5L/≈10 mg TOC [1]/L

Concentration of sodiumbenzoate: 120.4 mg/3.5L/≈20 mg TOC [1]/L

4th Test Solution with 20 mg C/L Sodiumbenzoate + 16 mg C/L TS

Date	Time (d)	mg CO2 generated in the test solution, cumulative	%TCO2 (=%Biodegradation)
06 -10 -05	2	86.68	19
06 -13 -05	5	197.27	42
06 -17 -05	9	275.61	59
06 -24 -05	16	342.47	73
06 -29 -05	21	354.56	76
07 -06 -05	28	360.40	77[4]
07 -07 -05	29	365.15	78 [5]

1) TOC: Total Organic Carbon

2) ThCO2: Theoritical amount of CO2 that can be generated by the test item

3) %TCO2: Percentage of total CO2 the test item has generated in relation to the ThCO2

4)The test solution was stopped by the addition of 1 mL conc. HCl;

5) The difference between this titration and that before is due to the liberation of CO2 after acidification of the test solution.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Calculated from the organic carbon content of the test item and the measured CO2 generation, 73% of the theoretical CO2 (ThCO2) has been generated by the test item within 28d of test period in the first culture with 84.6 mg of test item. 90% of the theoretical CO2 (ThCO2) has been generated by the test item within 28d in the second culture with 83.8 mg of test item. The mean degradation value of the test item was 82%

Executive summary:

The substance was tested for biodegradability according to CO2 -Evolution-Test, OECD 301B. Calculated from the organic carbon content of the test item and the measured CO2 generation, 73% of the theoretical CO2 (ThCO2) has been generated by the test item within 28d of test period in the first culture with 84.6 mg of test item. 90% of the theoretical CO2 (ThCO2) has been generated by the test item within 28d in the second culture with 83.8 mg of test item. The mean degradation value of the test item was 82%. The "10 -days-window", as required by the OECD guideline 301B is not regarded, as the test item is a polymer with a typical chain-distribution and not a pure substance. Nevertheless, the "10-days-window" was also met. Thus, the test item may be regarded as "readily biodegradable". the control item sodium benzoate was degraded 84%, the "10-days-window" being met within 9 days (72%). The total CO2 -evolution of the Blank was 77.3 mg CO2. Thus the test is regarded to be valid. The results obtained with the toxicity control indicate that there was no toxicity of the test item towards microorganisms at the concentration used within the test (73% degradation after 16 d).

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1998-02-05 to 1998-03-06

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(adopted July 17, 1992)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

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): Municipal sewage treatment plant, D-31137 Hildesheim
Activated sludge from the sewage plant at Hildesheim is weIl suited as it comprises mostly municipal sewage and hardly industrial chemical waste.

The activated sludge is maintained in an aerobic condition by aeration for four hours and then homogenized with a mixer. The sludge is filtered and the filtrate (30 µL) is subsequently used to initiale inoculation.

- Storage conditions: aerobic condition
- Storage length: 4 h
- Preparation of inoculum for exposure:
- Pretreatment: fitration
- Initial cell/biomass concentration: 3.8E08 CFU/L

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

test mat.

Initial conc.:

12.6 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral nutrient solution acc. to OECD 301 B / CO2 Evolution Test

- Test temperature: 22 ± 2 °C
- pH adjusted: no
- Continuous darkness: no, low light conditions (brown glass bottles)


TEST SYSTEM
- Culturing apparatus: 5000 mL brown glass flasks
- Number of culture flasks/concentration: 2 vessels for the test compound concentration (P1' P2), 1 vessel for the reference compound (R1), 2 vessels for monitoring the activity of the inoculum (C1, C2), 1 vessel for the toxicity control (T1)
- Method used to create aerobic conditions: vessels were connected to the system tor the production ot CO2 free air and aerated tor 24 h.

- Details of trap for CO2 and volatile organics if used: After 24 h the CO2 adsorption vessels were connected to the air outlets of the incubation vessels via a series of 3 gas wash bottles. Determination of CO2 was carried out by titration subsequent to complete adsorption of the released CO2 in a basic solution.


- Other: The necessary amounts of nutrient media and inoculum were placed in each of the incubation vessels. The vessels were then connected to the system tor the production ot CO2 free air and aerated tor 24 h. After 24 h the CO2 adsorption vessels were connected to the air outlets of the incubation vessels via a series of 3 gas wash bottles. The test and reference substance concentrations were placed into the incubation vessels, the vessels made up to 3 L with CO2 free aqua bidest. and connected to the system tor the production ot CO2 free air.


SAMPLING
- Sampling frequency: Backtitration of the residual Ba(OH)2 with 0.05 N HCI was carried out three times a week during the first ten days and thereafter twice weekly.


CONTROL AND BLANK SYSTEM
- Inoculum blank: nutrient solution and inocculum
- Abiotic sterile control: no
- Toxicity control: test substance (20 mg/L), reference substance (35 mg/L), nutrient solution and inocculum
- Functional control: reference substance (35 mg/L), nutrient solution and inocculum
- Other: An acute bacterial toxicity test was conducted on February 02, 1998 according to OECD 209 (Study No. BBR56471).

STATISTICAL METHODS:
The theoretical production of carbon dioxide (ThCO2) of the test item and functional control is calculated by the carbon content and the molecular formula, respectively.
The produced CO2 was calculated by: 1 mL HCl (c = 0.05 mol/L) = 1.1 mg CO2
The net amount of CO2 produced is calculated by correcting the results of the test item and functional control for endogenous CO2 production of the inoculum controls.
The biodegradation is calculated from the ratio theoretical CO2 production to net CO2 production.

Reference substance:

acetic acid, sodium salt

Preliminary study:

not performed

Parameter:

% degradation (CO2 evolution)

Value:

64

Sampling time:

14 d

Parameter:

% degradation (CO2 evolution)

Value:

73

Sampling time:

28 d

Details on results:

The test substance reached the 10% level (begin of biodegradation) after a short adaptation phase of 3 days. The pass level of abiodegradation > 60% was reached in a 10 d-window. After 14 days the biodegradtion came to 64% and to a maximum of 73% after 28 days.
In the toxicity control more than 25% biodegradation occured within 28 days. The test substance concentration can be assumed to have no inhibitory effect on the biodegradation of the functional control.

Results with reference substance:

The percentage degradation of the functional control reached the pass level of> 60% after 14 days with a degradation rate of 87% at this point of time.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The testsubstance proved to be readily biodegradable (>60% biodegradation after 28 d) in a study conducted in accordance with the OECD TG 301 B, and in compliance with GLP standards.

Executive summary:

The biodegradation of Polyoxyethylene(9) oleyl ether carboxylic acid was studied in accordance with the OECD TG 301 B, and in compliance with GLP standards for 28 d.

Polyoxyethylene(9) oleyl ether carboxylic acid  was tested in a concentration of 20 mg/L in duplicates, corresponding to a carbon content of 12.6 mgC/L.The biological degradation of the test substance was followed by titrimetric analyses of the quantity of CO2, which was produced by the respiration of bacteria. CO2 production was analysed at 0, 1, 4, 6, 8, 11, 14, 18, 21, 25 and 28 days of incubation. The degradation was finished on day 28 by acidification. The last titration was made on day 29, after the soluble CO2 was turned out over a period of 24h.

The CO2 production was calculated as the percentage of total CO2 that the test substance could have theoretically produced based on carbon composition. Biodegradability is therefore expressed as a percentageThCO2 (calculated by carbon content) and was calculated tor each titration of CO2.

In order to check the activity of the study system sodium acetate was used as functional control. The percentage degradation of the functional control reached the pass level of > 60% after 14 days with a degradation rate of 87% at this point of time thus fulfillling the quality criterion of the guideline.

In the toxicity control containing both test substance and reference compound 41% biodegradation occured within 14 days. The test substance can be assumed to have no inhibitory effect on the biodegradation of the functional control.

The test substance reached the 10% level (begin of biodegradation) after a short adaptation phase of 3 days. The pass level of biodegradation > 60% was reached in a 10d-window. After 14 days the biodegradation came to 64% and to a maximum of 73% after 28 days. ThereforePolyoxyethylene(9) oleyl ether carboxylic acid fulfills the OECD criteria of ready biodegradability in the 10-day window and after 28 days.

Description of key information

Two different tests according to OECD301B show both readily biodegradability (maintaining 10 -d-w).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable