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Biodegradation in water: screening tests

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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:
other: GLP-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
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Please refer to analogue approach justification provided in IUCLID section 13.
Parameter:
% degradation (CO2 evolution)
Value:
85.2
Sampling time:
28 d
Remarks on result:
other:
Remarks:
Source: RA-A, EC 701-177-3, LAUS, 05041406J605, 2005, CO2 Evolution
Conclusions:
The target substance is readily biodegradable based on experimental results with a structurally and chemically closely related source substance (85.2% in 28 d, OECD 301 B); read-across

Description of key information

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

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

There is no experimental study available, in which the ready biodegradability of the target substance Reaction mass of N-(1-oxooctadecyl)sarcosine and N-hexadecanoyl-N-methylglycine (EC 947-850-7) was assessed. Therefore, read-across to the structurally and chemically closely related source substance N-methyl-N-[C18-(unsaturated)alkanoyl]glycine (EC 701-177-3) was performed in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5 in order to fulfill the standard data requirements for the target substance.

Based on the structural and chemical similarity of the target and source substance, the selected source substance is considered a suitable representative for the assessment of the ready biodegradability of the target substance, in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5. A detailed analogue justification is provided in IUCLID section 13.

The available study with the source substance N-methyl-N-(C18-(unsaturated)alkanoyl)glycine (EC 701-177-3) was performed according to the OECD guideline 301 B using non-adapted activated sludge from a municipal waste water treatment plant. 20.0 mg/L test item (based on total organic carbon content) was inoculated with 25 mg/L activated sludge (suspended solids) for 28 d under aeration with CO2-free air. Inoculum blanks, an abiotic sterile control and a toxicity control were run in parallel. CO2 was trapped in bottles containing 0.25 M NaOH solution and the evolution of CO2 concentrations was followed by TOC analysis in regular intervals.

After 28 d incubation, the test item was degraded by 85.2% in terms of CO2 evolution and the 10-day window was met. Thus, the substance is readily biodegradable according to the OECD criteria. 

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. Therefore, it is concluded that the target substance Reaction mass of N-(1-oxooctadecyl)sarcosine and N-hexadecanoyl-N-methylglycine (EC 947-850-7) is readily biodegradable according to OECD guideline criteria.