Sodium N-methyl-N-(1-oxotetradecyl)aminoacetate

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:

12 Nov - 10 Dec 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: ISO 14593

Qualifier:

according to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace 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 was obtained from the municipal wastewater treatment plant Breisgauer Bucht, Germany on 05 Nov 2004
- Storage length: 6 days
- Pretreatment: The sludge was pre-incubated at 20 - 21 °C with CO2-free aeration for 6 days to keep the IC of the blank at a low level. The pH of the inoculum was determined three times and adjusted with NaOH. The activated sludge was washed twice by settling the sludge, decanting the supernatant and re-suspending the sludge in aerated tap water.
- Concentration of dry solids: 5.07 g/L

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

other: TIC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
A: 8.5 g KH2P04, 21.75 g K2HP04, 33.4 g Na2HP04* 2 H20, NH4Cl 0.5 g are dissolved in demineralised water and made up to 1 L.
B: 36.4 g CaCI2*2H20 is dissolved in demineralised water and made up to 1 L.
C: 22.5 g MgS04 * 7H20 is dissolved in demineralised water and made up to 1 L.
D: 0.25 g FeCI3* 6H20 0.25 9 is dissolved in demineralised water, stabilised with one drop of concentrated HCI and made up to 1 L.
For preparation of the mineral medium 10 mL of solution (A) is mixed with 800 mL bi-distilled water, 1 mL of solutions (B), (C) and (D) are added and made up to 1 L each.
- Test temperature: 20 - 22 °C
- pH adjusted: yes, with NaOH
- Aeration of dilution water: The mineral medium was aerated for 9 days with CO2-free air to reduce the IC.
- Suspended solids concentration: 4 mg dry solids per litre

TEST SYSTEM
- Culturing apparatus: Serum bottles, 120 mL, sealed with silicon septa and aluminium caps
- Number of culture flasks/concentration: 17
- Method used to create aerobic conditions: aeration of mineral medium
- Measuring equipment: TOC 5000 A (Shimadzu) with autosampler
- CO2 absorption medium: 28.0 g NaOH were dissolved in 100 mL bidistilled water in a closed recipient (7 M NaOH).

SAMPLING
- Sampling frequency: On day 7, 14, 21 and 28 samples for TIC-measurements were taken.
- Sampling method: Three flasks of each flask series were withdrawn after 7, 14 and 21 days and 1 mL each of 7 M NaOH were added through the septa for CO2-absorption in the liquid phase. On day 28 a sampling of five flasks was done. The samples were shaken for at least two hours and after se

CONTROL AND BLANK SYSTEM
- Inoculum blank: 17 flasks
- Toxicity control: 17 flasks

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

71

Sampling time:

28 d

Details on results:

- All validity criteria were met.
- The mean degradation extent in the inhibition control was 70% at the end of the test. Therefore the test item had no toxic effect on the inoculum.
- Degradation kinetics (mean values from 3 to 5 replicates): 51% after 7 days, 61% after 14 days, 83% after 21 days and 71% after 28 days
- The criterion for biodegradation (60% ThCO2 within 28 d) could be met: 71% in 28 d
- The criterion for ready biodegradation was not met: At the end of the 10-day window, on day 12, mean degradation was below 60%.

Results with reference substance:

- The reference compound sodium benzoate reached the pass levels for ready biodegradability within 7 days.

Table 1: Interpolated degradation extents of the test item for the evaluation of the 10-day window. Values for 7 and 14 days were measured.

 

Day	1	2	3	4	5	6	7	8	9	10	11	12	13	14
Degradation (%)	7	15	22	29	37	44	51	53	54	55	57	58	60	61

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The pass level of 60% was reached in a ready biodegradation test (OECD 310) within 28 days, but the 10-day window criterion was not met.

Reference 2

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 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: Cambridge Sewage Treatment Works, Cowley Road; date of collection: 29 January 2013
- Pretreatment: Sieved to 850 µm to remove coarse particulates, settled and centrifuged at ~ 4000 rpm for ~ 5-10 minutes. The supernatant discarded, sludge resuspended in mineral media and centrifuged at ~ 4000 rpm for ~ 5-10 minutes, the supernatant discarded again and homogenised thoroughly by mechanical stirring (spoon). Dry sludge solids determined on the pellet produced.
- Concentration of dry sludge solids: 0.03 g/L

Duration of test (contact time):

28 d

Initial conc.:

20.01 mg/L

Based on:

other: TOC

Initial conc.:

104.95 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineal medium
- Test temperature: 22 ± 2 °C
- Aeration of dilution water: Aeration by the passage of carbon dioxide free air at a controlled rate
- Suspended solids concentration: 0.03 g/L dry sludge solids
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Conical flasks of nominal volume 2000 mL filled with 1500 mL of inoculated mineral medium
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Atmospheric air was pumped into the test system and scrubbed clean of carbon dioxide by passing over soda lime.
- Measuring equipment: Tekmar-Dohrmann Phoenix 8000 (UV-Persulfate Analyser)
- Details of trap for CO2 and volatile organics if used: The carbon dioxide is trapped in sodium hydroxide and is measured as Dissolved Inorganic Carbon (DIC).
- Other: The test solutions were stirred for the duration of the study.

SAMPLING
- Sampling method: On day 28, 2 mL of 50% hydrochloric acid is added to each bioreactor, which are then aerated overnight, to drive off the remaining carbon dioxide. One last analysis of evolved carbon dioxide is made on day 29.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates
- Toxicity control: 1 replicate

Reference substance:

other: sodium acetate

Parameter:

% degradation (CO2 evolution)

Value:

83

Sampling time:

28 d

Details on results:

- The mean degradation extent in the inhibition control was 81% at the end of the test. Therefore the test item had no toxic effect on the inoculum.
- The criterion for biodegradation (60% ThCO2 within 28 d) could be met: 83% in 28 d
- The criterion for ready biodegradation was not met: At the end of the 10-day window, on day 13, mean degradation was below 60%.

Results with reference substance:

The reference substance reached the pass level for ready biodegradability (91% on day 29).

Experience has shown that a 10 day window is commonly not achieved with this protocol as the carbon dioxide produced at any time point will take time to be sparged into the sodium hydroxide traps. Carbon dioxide is water soluble, the degree of which is pH dependent, therefore, it can be retained by the bioreactor throughout the test and only released upon acidification.

Table 1: Percentage biodegradation

Time (days)	Reference			Test chemical			Toxicity control
	1	2	Mean	1	2	Mean
0	0	0	0	0	0	0	0
2	43	46	45	1	2	1	19
5	55	59	57	36	35	35	38
7	59	63	61	46	41	43	51
9	61	65	63	52	48	50	56
14	66	70	68	63	58	60	64
19	69	73	71	66	62	64	71
23	71	91	81	72	65	69	76
28	75	93	84	76	67	71	80
29	76	94	85	76	68	72	80
29	86	97	91	86	80	83	81

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 May - 14 Jun 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

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge was collected on 13 May 2005 from the municipal waste water treatment plant Neustadt/Weinstrasse, Lachen-Speyerdorf
- Method of cultivation: The sludge was continuously aerated and washed with tap water and OECD medium
- Concentration of suspended solids: 12.78 g/L

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

other: TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium as recommended by the guideline
- Test temperature: 21 ± 1 °C
- Aeration of dilution water: All vessels were aerated overnight with CO2-free air prior to test start and during the test
- Suspended solids concentration: 25 mg/L

TEST SYSTEM
- Culturing apparatus: 2 L Glass bottles, 1500 mL fill volume
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Aeration with CO2-free air
- Details of trap for CO2: Outgoing air from the test vessels passed two serial bottles containing 0.25 M NaOH solution
- Other:

SAMPLING
- Sampling frequency: Measurement of evolved CO2 on days 2, 4, 6, 8, 10, 14, 21, 28 and 29
- Sampling method: 0.5 mL aliquots of the NaOH solution was sampled at each time point and analysed using a TOC 5050A (Shimadzu)

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 vessels
- Abiotic sterile control: 1 vessel
- Toxicity control: 1 vessel

Reference substance:

aniline

Parameter:

% degradation (CO2 evolution)

Value:

85.2

Sampling time:

28 d

Details on results:

- The toxicity control attained 98.3% degradation.
- Abiotic degradation was 26.6%.

Results with reference substance:

The reference substance attained 79.9% degradation after 28 days.

Table 1: Percentage of Degradation

Day	% Degradation
	Reference	Test Item (mean of duplicates)	Abiotic Control	Toxicity Control
2	2.6	1.7	3.4	3.2
4	26.5	24.1	3.1	53.5
6	56.1	47.5	11.3	68.7
8	66.5	57.4	16.0	75.8
10	71.1	61.3	8.6	79.7
14	76.2	72.9	17.6	86.7
21	85.0	88.3	22.9	97.5
28	77.6	83.0	28.0	99.6
29	79.9	85.2	26.6	98.3

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable (85.2% in 28 d, OECD 301 B); read-across

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Four experimental studies are available, which cover the ready biodegradability of the target substance Sodium N-methyl-N-(1-oxotetradecyl)aminoacetate (CAS 30364-51-3). In the key study, read-across in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5 was performed to the structurally and chemically related source substance N-methyl-N-[C18-(unsaturated)alkanoyl]glycine (EC 701-177-3). Since the determining factor for biodegradability is carbon chain length, this source substance is considered a worst-case approach based on its longer chain length (C18) compared to the target substance (C14). A detailed read-across approach justification is provided in IUCLID section 13.

The first study was performed with the structurally and chemically related source substance N-methyl-N-[C18-(unsaturated)alkanoyl]glycine (EC 701-177-3),according to OECD guideline 301 B. In this study, 20 mg/L test substance (based on TOC) was inoculated with 25 mg/L domestic, non-adapted activated sludge for 28 d. After 28 d, the test item was degraded by 85.2% in terms of CO2 evolution. Thus, the source substance N-methyl-N-[C18-(unsaturated)alkanoyl]glycine (EC 701-177-3) is readily biodegradable according to guideline criteria.

Two studies with the target substance itself further substantiate the degradability of the target substance. In the first supporting study performed according to OECD 301B, activated sludge was used as inoculum with a test substance concentration of 104.95 mg/L. A mean degradation of 83 % was observed after 28 days, but the 10-day window was not achieved (60% at day 14 instead of day 13). In the second supporting study performed according to OECD 310 domestic activated sludge was used as inoculum with a test concentration of 20 mg/L based on total inorganic carbon (TIC). 71% mean biodegradation was reported after 28 days and the 10-day window was not achieved. (60% biodegradation obtained at day 13, instead of day 12).

Based on the structural and chemical similarity of the target and source substance, the target substance is expected to exhibit a similar environmental fate profile as the selected source substance. Since the source substance represents a worst-case scenario with regard to carbon chain lengths and the 10-d window in both supporting studies was only narrowly missed by 1 d, it is concluded that the target substance substance Sodium N-methyl-N-(1-oxotetradecyl)aminoacetate (CAS 30364-51-3) is readily biodegradable according to OECD guideline criteria.