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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016-06-01 to 2016-08-10
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report date:
2016

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
2008
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
1992
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Didodecyl hydrogen citrate
EC Number:
247-146-3
EC Name:
Didodecyl hydrogen citrate
Cas Number:
25637-88-1
Molecular formula:
C30H56O7
IUPAC Name:
didodecyl hydrogen citrate
Constituent 2
Chemical structure
Reference substance name:
Tridodecyl 2-hydroxypropane-1,2,3-tricarboxylate
EC Number:
265-671-6
EC Name:
Tridodecyl 2-hydroxypropane-1,2,3-tricarboxylate
Cas Number:
65277-53-4
Molecular formula:
C42H80O7
IUPAC Name:
tridodecyl citrate
Constituent 3
Chemical structure
Reference substance name:
Dodecyl dihydrogen 2-hydroxypropane-1,2,3-tricarboxylate
EC Number:
278-950-2
EC Name:
Dodecyl dihydrogen 2-hydroxypropane-1,2,3-tricarboxylate
Cas Number:
78568-45-3
Molecular formula:
C18H32O7
IUPAC Name:
2-[2-(dodecyloxy)-2-oxoethyl]-2-hydroxysuccinic acid
Test material form:
solid

Study design

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history, procedure): sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany; withdrawn on June 23th, 2016
- Storage conditions: kept aerobic until use
- Concentration of sludge: concentration used in the test was 29.6 mg dry mass/litre
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
100 mg/L
Based on:
act. ingr.
Initial conc.:
32 mg/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: as stipulated in OECD guideline 301
- Additional substrate: no
- Test temperature: 22°C ± 1°C
- pH: 7.4 ± 0.2
- pH adjusted: no
- Aeration of dilution water: yes
- Suspended solids concentration: 29.6 mg/L
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: closed 500 mL glass vessels at a medium volume of 250 mL
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aeration
- Measuring equipment: SAPROMAT respirometer (VOITH Inc.)
- Details of trap for CO2 and volatile organics if used: carbon dioxide is adsorbed in a suitable adsorbent
- Other: The consumption of oxygen is determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant gas volume in the respirometer flask.

SAMPLING
- Sampling frequency: measurement and recording of the oxygen demand was carried out continuously
- At test end, NH3-N and NO3-N concentrations were measured in control, test item and abiotic control assays.

CONTROL AND BLANK SYSTEM
Blank control: The blank control consists of inoculated mineral medium only.
Abiotic control: An abiotic control containing test item at 100 mg per litre sterilized mineral test medium (25 mg/250 mL) was applied. The assay was sterilized by adding HgCl2.
Procedural control: A procedural control containing sodium benzoate as reference item at 100 mg per litre mineral test medium (25 mg/250 mL) was applied.
Toxicity control: A toxicity control containing test item at 100 mg per litre and reference item at 100 mg per litre mineral test medium (25 mg/250 mL) was applied.


STATISTICAL METHODS:
Reference substance
Reference substance:
benzoic acid, sodium salt
Remarks:
100 mg/L

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
13.6
St. dev.:
2
Sampling time:
14 d
Remarks on result:
other: 100 mg/L
Parameter:
% degradation (O2 consumption)
Value:
31.7
St. dev.:
2.3
Sampling time:
28 d
Remarks on result:
other: 100 mg/L
Parameter:
% degradation (O2 consumption)
Value:
25.5
St. dev.:
0
Sampling time:
14 d
Remarks on result:
other: 32 mg/L
Parameter:
% degradation (O2 consumption)
Value:
46.1
St. dev.:
0.9
Sampling time:
28 d
Remarks on result:
other: 32 mg/L
Details on results:
The biodegradation of the test item after 28 days of incubation in the static test was found to be 32 % (SD = 2.3 %) and 46 % (SD = 0.9 %) in the assays with 100 mg/L and 32 mg/L, respectively. The biodegradation within the 10-day-window was 18 % and 25 % in the assays with 100 mg/L and 32 mg/L, respectively. The 10-day-window started at day 3 for a concentration of 32 mg test item per liter and at day 8 - 11 for a concentration of 100 mg test item per liter.
The biodegradation of the item mixture in the toxicity control was found to be 39 % after 14 days of incubation. Thus, the demanded threshold value of 25 % is exceeded and the test item can be identified as non-toxic in a ready biodegradability test. The reference item sodium benzoate was degraded to 84 % within the first 14 days.
According to the OECD guideline 301F, the test item must be considered as being not readily biodegradable under the test conditions.

BOD5 / COD results

Results with reference substance:
The reference item sodium benzoate was degraded to 91 % within the first 14 days.

Any other information on results incl. tables

Oxygen consumption. Cumulated consumption (mg O2/L) after 14 days: Single and mean values of the parallel test vessels and standard deviation. Test suspension A, abiotic and procedural control: 100 mg/L; Test suspension B: 24 mg/L;Toxicity control: 200 mg/L.

vessel

Inoculum blank

Test suspension A

Test suspension B

Procedural control

Toxicity control

Abiotic control

1

10

48

31

150

175

2

2

11

41

31

152

173

1

Mean

11

45

31

151

174

2

SD

1

5

0

1

1

1

 

Oxygen consumption. Cumulated consumption (mg O2/L) after 28 days: Single and mean values of the parallel test vessels and standard deviation. Test suspension A, abiotic and procedural control: 100 mg/L; Test suspension B: 24 mg/L;Toxicity control: 200 mg/L.

vessel

Inoculum blank

Test suspension A

Test suspension B

Procedural control

Toxicity control

Abiotic control

1

15

101

54

163

232

6

2

20

93

55

164

233

3

Mean

18

97

55

164

233

5

SD

4

6

1

1

1

2

 

Percent degradation. Degradation after 14 days: Single and mean values of the parallel test vessels and standard deviation.

vessel

Test suspension A

Test suspension B

Procedural control

Toxicity control

Abiotic control

1

14.9

25.5

83.8

39.4

0.8

2

12.2

25.5

85.0

38.9

0.4

Mean

13.6

25.5

84.4

39.2

0.6

SD

2.0

0

0.8

0.3

0.3

 

Percent degradation. Degradation after 28 days: Single and mean values of the parallel test vessels and standard deviation.

vessel

Test suspension A

Test suspension B

Procedural control

Toxicity control

Abiotic control

1

33.3

45.5

87.4

51.4

2.4

2

30.1

46.7

88.0

51.6

1.2

Mean

31.7

46.1

87.7

51.5

1.8

SD

2.3

0.9

0.4

0.2

0.8

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
In this test the test substance was not readily biodegradable.
Executive summary:

The biodegradation of the substance was investigated in a study conducted according to OECD Guideline 301 F, adopted 17th July 1992 (Ready Biodegradability: Manometric Respirometry Test) and EU Method C.4-D, 2008, over a period of 28 days using activated sludge sampled from a sewage treatment plant mainly fed with municipal wastewater as inoculum. The biodegradation rate was determined by measurement of O2 consumption. Inoculum blank, toxicity control and procedural/functional control with the reference substance Sodium benzoate were performed. The test was performed with 32 and 100 mg/L test substance concentration.The functional control reached the pass level >60% after 14 d (84%).

The biodegradation of the test item after 28 days of incubation in the static test was found to be 32 % (SD = 2.3 %) in the assays with 100 mg/L and 46 % (SD = 0.9 %) in the assays with 32 mg/L.

For a concentration of 100 mg test item per liter biodegradation within the 10-day window was found to be 18 %. For a concentration of 32 mg test item per liter biodegradation within the 10-day-window was found to be 25 %. The 10-day-window started at day 3 for a concentration of 32 mg test item per liter and at day 8 - 11 for a concentration of 100 mg test item per liter.

The degradation of the reference substance sodium benzoate had reached 84 % within the first 14 days. The difference of extremes of replicate values of the removal of the test item at the end of the test for 100 mg/L and 32 mg/L, respectively, is less than 20%. Therefore, the test can be considered as valid. No inhibitory effects of the test item were observed (more

than 25 % degradation occurred within 14 days) in the toxicity control.

According to the guideline, PC-2016-670 must be considered as being not readily biodegradable under the test conditions.