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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Endpoint:
biodegradation in water: sewage treatment simulation testing
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
For details on endpoint-specific justification, please see read-across justification document (analogue approach) in section 13.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
assessment report
Radiolabelling:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Duration of test (contact time):
26 d
Initial conc.:
200 µg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
test mat. analysis
Test performance:
Mean hydraulic retention time: 6 h
The total influent flow of 0.5 L/h was maintained by retention time dosing the organic medium and test item stock solution (control: methanol) in appropriate amounts. All solutions were pumped directly into the aeration vessels.
Influent flow
- Organic medium: 500 mL/h
- Test item solution (control methanol): 0.05 mL/h
Parent/product:
parent
Compartment:
total system
Remarks:
STP effluent and STP sludge
Key result
% Degr.:
>= 99.87 - <= 100
Parameter:
other: mean biodegradation during plateau phase (effluent & sludge)
Sampling time:
23 d
Remarks on result:
other: RA from HYEQS
Transformation products:
not measured
Evaporation of parent compound:
no
Volatile metabolites:
no
Residues:
no

DOC Concentration, Degradation and Suspended Solids (Control Unit)

Study

DOC

Suspended solids

day

Date

[mgC/L]

Elimination

Activated Sludge

Effluent

Influent

Effluent

[%]

[g DW/L]

[g DW/L]

0

16.11.09

107.5

2.8

1

17.11.09

107.5

26.8

75

3.4

2

18.11.09

108.2

19.1

82

2.9

0.47

3

19.11.09

108.2

19.4

82

2.7

0.61

4

20.11.09

97.9

17.8

84

3.2

#

5

21.11.09

97.9

23.6

76

2.5

#

6

22.11.09

102.4

14.0

86

2.7

0.76

7

23.11.09

102.4

15.6

85

3.1

0.88

8

24.11.09

100.1

13.6

87

3.3

0.91

9

25.11.09

100.1

10.3

90

3.2

0.59

10

26.11.09

104.1

12.8

87

3.2

0.65

11

27.11.09

104.1

13.1

87

3.4

0.93

12

28.11.09

89.6

11.4

89

3.7

0.86

13

29.11.09

89.6

9.6

89

3.6

0.80

14

30.11.09

105.9

16.2

82

4.1

0.95

15

01.12.09

105.9

15.5

85

3.6

0.79

continued

Study

DOC

Suspended solids

day

Date

[mgC/L]

Elimination

Activated sludge

Effluent

Influent

Effluent

[%]

[g DW/L]

[g DW/L]

16

02.12.09

101.9

10.9

90

3.7

0.91

17

03.12.09

101.9

13.4

87

4.7

0.91

18

04.12.09

98.6

10.5

90

4.2

0.79

19

05.12.09

98.6

13.2

87

4.0

0.85

20

06.12.09

90.8

11.1

89

4.1

1.03

21

07.12.09

90.8

11.8

87

4.0

0.93

22

08.12.09

106.6

17.7

81

4.4

1.16

23

09.12.09

106.6

12.8

88

3.9

0.86

24

10.12.09

105.9

14.4

86

3.8

0.97

25

11.12.09

105.9

13.5

87

3.5

0.47

26

12.12.09

96.7

15.2

86

3.9

1.17

27

13.12.09

96.7

13.7

86

4.0

1.18

28

14.12.09

108.5

15.5

84

3.6

1.13

29

15.12.09

108.5

15.1

86

3.2

0.82

30

16.12.09

9.7

91

3.9

0.97

DOC Concentration, Degradation and Suspended Solids (Test Item Unit)

Study

Test

Day of

DOC

Suspended solids

day

phase

test item application

Date

[mgC/L]

Elimination

Activated Sludge

Effluent

Influent

Effluent

[%]

[g DW/L]

[g DW/L]

0

Acclima- tisation

16.11.09

107.5

2.8

1

17.11.09

107.5

21.2

80

3.0

2

18.11.09

108.2

16.7

84

3.0

0.45

3

19.11.09

108.2

16.6

85

2.9

0.48

4

Adaptation

0

20.11.09

97.9

21.0

81

2.7

#

5

1

21.11.09

97.9

20.7

79

2.7

#

6

2

22.11.09

102.4

13.9

86

2.3

0.72

7

3

23.11.09

102.4

13.4

87

3.4

1.00

8

Plateau Phase

4

24.11.09

100.1

11.6

89

3.4

0.93

9

5

25.11.09

100.1

10.7

89

3.0

0.60

10

6

26.11.09

104.1

14.8

85

3.2

0.66

11

7

27.11.09

104.1

18.6

82

3.4

0.80

12

8

28.11.09

89.6

14.2

86

3.5

0.90

13

9

29.11.09

89.6

11.5

87

3.5

0.82

14

10

30.11.09

105.9

15.9

82

3.8

0.94

15

11

01.12.09

105.9

13.8

87

3.4

0.78

16

12

02.12.09

101.9

11.8

89

3.5

0.93

17

13

03.12.09

101.9

15.8

84

3.7

0.93

18

14

04.12.09

98.6

15.2

85

3.5

0.83

19

15

05.12.09

98.6

16.5

83

3.4

0.84

20

16

06.12.09

90.8

14.2

86

3.9

1.04

21

17

07.12.09

90.8

13.7

85

3.6

0.85

22

18

08.12.09

106.6

22.7

75

4.2

1.28

23

19

09.12.09

106.6

15.5

85

3.7

0.84

24

20

10.12.09

105.9

18.7

82

3.9

0.90

25

21

11.12.09

105.9

11.0

90

3.5

0.48

26

22

12.12.09

96.7

11.6

89

4.2

1.11

27

23

13.12.09

96.7

9.8

90

4.6

1.11

28

24

14.12.09

108.5

9.8

90

4.1

1.09

29

25

15.12.09

108.5

10.3

90

3.9

0.88

30

26

16.12.09

6.9

94

2.9

0.84

Validity criteria fulfilled:
yes
Executive summary:

The study used as source investigated the elimination and degradation of HYEQS in the STP. The study results of the source substance were considered applicable to the target substance. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13.

Endpoint:
biodegradation in water and sediment: simulation testing, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
For details on endpoint-specific justification, please see read-across justification document (analogue approach) in section 13.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
assessment report
Radiolabelling:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
other: River water, sewage effluent, and activated sludge liquor
Duration of test (contact time):
28 d
Initial conc.:
75 µg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
other: % Recovered as Metabolites... (see attached file)
Reference substance:
not required
Test performance:
Please see Tables 1 and 2 below under Remarks on Results.
Compartment:
other: water, material (mass) balance
% Recovery:
86.6
St. dev.:
10.7
Parent/product:
parent
Compartment:
water
% Degr.:
100
Parameter:
other: % disappearance of Parent
Sampling time:
5 d
Parent/product:
parent
Compartment:
water
% Degr.:
39.3
Parameter:
CO2 evolution
Sampling time:
7 d
% Degr.:
67.8
Parameter:
CO2 evolution
Sampling time:
28 d
Parent/product:
parent
Compartment:
water
Key result
% Degr.:
80
Parameter:
CO2 evolution
Sampling time:
21 d
% Degr.:
58.4
Parameter:
other: % Recovered as Metabolites
Sampling time:
7 d
Remarks on result:
other: 0% in all Abiotic samples for all time points.
Parent/product:
product
Compartment:
water
Key result
% Degr.:
11.6
Parameter:
other: % Recovered as Metabolites
Sampling time:
21 d
% Degr.:
2.23
Parameter:
other: % Recovered with Solids
Sampling time:
7 d
% Degr.:
8.4
Parameter:
other: % Recovered with Solids
Sampling time:
21 d
Key result
Compartment:
entire system
DT50:
0.61 d
Type:
other: calculated from first order rate constant
Remarks on result:
other: primary biodegradation
Key result
Compartment:
entire system
DT50:
7.7 d
Type:
other: calculated from first order rate constant
Remarks on result:
other: mineralization
Other kinetic parameters:
first order rate constant
Transformation products:
not specified
Details on transformation products:
In the bioactive treatment, parent disappeared with 56% remaining after 13 hours, 11% remaining after 72 hours, and none present after day 5. The disappearance of parent was associated with the transient appearance of a group of poorly resolved peaks with Rf values from 0.2-0.33. These metabolites reached a maximum level of 73% after 22 hours and decreased to 12% by day 21. A nearly 29 hour lag time was observed in 14CO2 evolution. Mineralization reached 22% after 72 hours and 68% after day 28. Incorporation into solids remained low throughout the experiment.

The abiotic control revealed a single peak at Rf 0.4-0.5 through day 14. After this time, about 20% polar materials were observed in this treatment, indicating chemical oxidation or renewed microbial activity.
Evaporation of parent compound:
not measured
Volatile metabolites:
not measured
Residues:
not measured
Details on results:
TEST CONDITIONS
- Aerobicity, moisture, temperature and other experimental conditions maintained throughout the study: Yes
- Anomalies or problems encountered (if yes): N/A


MAJOR TRANSFORMATION PRODUCTS
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed: The disappearance of parent was associated with the transient appearance of a group of poorly resolved peaks with Rf values from 0.2-0.33. These materials reached a maximum level of 73% after 22 hours and decreased to 12% by day 21.
- Range of maximum concentrations in % of the applied amount at end of study period:N/A


MINOR TRANSFORMATION PRODUCTS
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed: N/A
- Range of maximum concentrations in % of the applied amount at end of study period:N/A


TOTAL UNIDENTIFIED RADIOACTIVITY (RANGE) OF APPLIED AMOUNT: N/A


EXTRACTABLE RESIDUES
- % of applied amount at day 0: N/A
- % of applied amount at end of study period: N/A


NON-EXTRACTABLE RESIDUES
- % of applied amount at day 0: N/A
- % of applied amount at end of study period: N/A


MINERALISATION
- % of applied radioactivity present as CO2 at end of study: mineralization reached 22% after 72 hr, and 68% by day 28.


VOLATILIZATION
- % of the applied radioactivity present as volatile organics at end of study:N/A


STERILE TREATMENTS (if used)
- Transformation of the parent compound: In the abiotic treatment, at the end of 21 days, 68.1% was parent, 26.1% was metabolite, 5.8% was in the solids, and 0.0% was CO2.
- Formation of transformation products: 0% recovered as metabolites in the abiotic sample from time 0 through 7 days; 26% at days 14, 21.
- Formation of extractable and non-extractable residues:N/A
- Volatilization:N/A


RESULTS OF SUPPLEMENTARY EXPERIMENT (if any):N/A
Results with reference substance:
A reference was not part of the study. However, a total of 6 surfactant materials were tested in this study, including KDB.

Table 1. Summary of KDB-Base Results

Time (hr)

% Parent

% CO2

% Metabolite

Total % Biomass

0.25

96.30

N/A

3.51

0.18

0.5

92.90

N/A

6.80

0.30

1

80.98

13.62

4.70

0.70

2

85.37

6.79

7.10

0.74

4

84.47

6.99

7.59

0.95

6

79.41

3.08

16.58

0.94

9

65.99

6.76

27.36

0.52

13

56.56

3.31

39.61

0.52

17

40.71

3.89

54.90

0.49

22

21.73

4.98

72.58

0.70

29

24.91

10.93

63.65

0.51

48

13.45

16.09

69.50

0.96

72

11.09

21.60

62.98

4.32

Day 5

0.00

43.01

53.03

3.96

Day 7

0.00

39.34

58.43

2.23

Day 14

0.00

41.22

41.11

17.66

Day 21

0.00

79.98

11.62

8.40

Day 28

N/A

67.84

N/A

N/A

Day 35

N/A

75.89

N/A

N/A

*Abiotic Control Mean ± S.D.

98.80 ± 0.58

N/A

0.00

1.20 ± 0.58

*Excluding day 14 and 21      N/A-not analyzed

Table 2. Kinetic Analysis of KDB-Base Results.

Process

Function

r2

A (%)

k1 (day-1)

Biodegradation

First order

0.980

95.30 (± 2.85)

1.13 (± 0.12)

Mineralization

First order

0.956

75.66 (± 6.72)

0.087 (± 0.019)

A= Initial concentration (Decay) Asymptote (First order Production).

k1=First order rate constant

Validity criteria fulfilled:
not applicable
Executive summary:

The study used as source investigated the biodegradation of HYEQS in a test performed equivalent to OECD 314D. The study results of the source substance were considered applicable to the target substance. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13.

Endpoint:
biodegradation in water: sewage treatment simulation testing
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
For details on endpoint-specific justification, please see read-across justification document (analogue approach) in section 13.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
assessment report
Radiolabelling:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Duration of test (contact time):
52 d
Initial conc.:
300 µg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Test performance:
The system was started with the conditions described above.
- Set-up of the test units
- Inoculation with activated sludge
- Dosage of sewage (organic medium)
- Sludge adhering to the walls of the activated sludge units was resuspended
- After the system had stabilized and the removal of DOC of the sewage was efficient (> 80 %) the test item solution (control: methanol) was applied.
- Sampling and measurements as given above
- Calculation of ultimate biodegradation of the organic medium, elimination/adsorption and primary biodegradion of the test item
- Completion of the study after a sufficient degree of elimination and the plateau was reached (> 90 %).

Parent/product:
parent
Compartment:
water
Remarks:
STP effluent
Key result
% Degr.:
96
Parameter:
other: (C20 fraction) primary biodegradation
Sampling time:
52 d
Remarks on result:
other: RA from C20/22-ATQ trocken; median of all samples
Parent/product:
parent
Compartment:
water
Remarks:
STP effluent
Key result
% Degr.:
91
Parameter:
other: (C22 fraction) primary biodegradation
Sampling time:
52 d
Remarks on result:
other: RA from C20/22-ATQ trocken; median of all samples
Transformation products:
not measured
Evaporation of parent compound:
no
Volatile metabolites:
no
Residues:
no

Influent and Effluent Concentration and Elimination of C20-fraction
                   of C20/22-ATQ trocken (exemplarily)

Study
day

Day of
test item application

Date

Influent concentration

Effluent concentration

Elimination

[µg/L]

 [µg/L]

[%]

3

0

20.04.09

42.19

 

¿

4

1

21.04.09

42.19

0.228

99.46

5

2

22.04.09

41.00

0.228

99.46

6

3

23.04.09

41.00

0.685

98.33

7

4

24.04.09

41.57

0.228

99.44

9

6

26.04.09

42.19

0.228

99.45

10

7

27.04.09

42.19

0.228

99.46

11

8

28.04.09

42.50

0.228

99.46

12

9

29.04.09

42.50

0.685

98.39

13

10

30.04.09

42.00

0.228

99.46

14

11

01.05.09

42.00

0.228

99.46

15

12

02.05.09

41.91

0.685

98.37

16

13

03.05.09

41.91

0.685

98.37

17

14

04.05.09

41.99

0.685

98.37

18

15

05.05.09

41.99

0.685

98.37

19

16

06.05.09

42.01

0.228

99.46

20

17

07.05.09

42.01

0.228

99.46

21

18

08.05.09

42.94

0.685

98.37

22

19

09.05.09

42.94

0.228

99.47

23

20

10.05.09

41.90

0.228

99.47

24

21

11.05.09

41.90

0.228

99.46

25

22

12.05.09

42.61

0.228

99.46

26

23

13.05.09

42.61

0.228

99.46

27

24

14.05.09

42.13

0.228

99.46

28

25

15.05.09

42.13

0.228

99.46

29

26

16.05.09

41.57

0.228

99.46

30

27

17.05.09

41.57

0.685

98.35

31

28

18.05.09

42.54

0.228

99.45

32

29

19.05.09

42.54

0.685

98.39

33

30

20.05.09

41.21

0.228

99.46

34

31

21.05.09

41.21

0.685

98.34

35

32

22.05.09

42.24

0.228

99.45

36

33

23.05.09

42.24

0.685

98.38

37

34

24.05.09

42.40

0.228

99.46

continued

Study
day

Day of
test item application

Date

Influent concentration

Effluent concentration

Elimination

[µg/L]

 [µg/L]

[%]

38

35

25.05.09

42.40

0.228

99.46

39

36

26.05.09

42.64

0.228

99.46

40

37

27.05.09

42.64

0.228

99.47

41

38

28.05.09

42.09

0.685

98.39

42

39

29.05.09

42.09

0.228

99.46

43

40

30.05.09

42.14

0.228

99.46

44

41

31.05.09

42.14

0.228

99.46

45

42

01.06.09

42.26

0.685

98.37

46

43

02.06.09

43.27

0.685

98.38

47

44

03.06.09

43.27

0.228

99.47

48

45

04.06.09

43.02

0.228

99.47

49

46

05.06.09

43.02

0.228

99.47

50

47

06.06.09

42.44

0.228

99.47

51

48

07.06.09

42.44

0.228

99.46

52

49

08.06.09

41.65

0.228

99.46

53

50

09.06.09

41.65

0.228

99.45

54

51

10.06.09

43.70

1.39#

96.66

55

52

11.06.09

¿

0.228

99.48

Validity criteria fulfilled:
yes
Executive summary:

The study used as source investigated the elimination and degradation extent of C20/22-ATQ trocken in the STP. The study results of the source substance were considered applicable to the target substance. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13.

Endpoint:
biodegradation in water: sewage treatment simulation testing
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Justification for type of information:
For details on endpoint-specific justification, please see read-across justification document (category approach) in the linked category of dimethylalkylamines.
Principles of method if other than guideline:
Deviations from guidline: No DOC concentrations were determined. The purpose of the measurement was to check the rate of elimination of the test item. Therefore only one model activated sludge plant was used. Test duration was limited to 6 days. Inoculation was made by introducing 3 litre of the composite inoculum with a dry matter content of 2 g/L in the aeration vessel, because of the short duration of the test.
Oxygen conditions:
aerobic
Inoculum or test system:
mixture of sewage, soil and natural water
Details on source and properties of surface water:
Water from river Alz, southern Germany, the only discharge of the Chiemsee
Duration of test (contact time):
6 d
Initial conc.:
>= 4 - <= 28 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Parent/product:
parent
Compartment:
water
Remarks:
STP effluent
Key result
% Degr.:
> 99.6
St. dev.:
0.63
Parameter:
test mat. analysis
Remarks on result:
other: RA from C12-14-DMA; mean of 6 daily measurements (days 1-6); 95% CI: +/- 0.7
Transformation products:
not specified
Details on transformation products:
Only elimination was determined.
Details on results:
See table under "Any information on results incl. tables".
According to the guideline, DRc (degradation rate, corrected for material transfer due to transinoculation procedure) was calculated as follows from DR (degradation rate):
DRc = (4*DR - 100)/3

Results with respect to test material:

date

inflow
[µg/L]

outflow
[µg/L]

DR
[%]

DRc

[%]

05/09/00

14000

 

 

 

05/10/00

5000

60

99.57

99.43

05/11/00

4000

5

99.90

99.87

05/12/00

13000

48

98.80

98.40

05/15/00

22000

2

99.98

99.98

05/16/00

28000

8

99.96

99.95

05/17/00

 

1

> 99.99

> 99.99

Validity criteria fulfilled:
not applicable
Remarks:
No clear validity criteria are stated by the guideline (OECD 303, 1981)
Executive summary:

The study used as source investigated the elimination extent of C12-14-DMA in the STP (STP simulation test based on OECD 303A). The study results of the source substance were considered applicable to the target substance. Justification and applicability of the read-across approach (category approach) is outlined in the read-across report in the linked category of dimethylalkylamines.

Description of key information

Biodegradation in Sewage Treatment Plants
One Key studies is available for C12-14 DMA sufficiently reported to demonstrate an elimination of >99.6% in an OECD303A Test. This result is supported by further key studies with the structural analogues HYEQS and C20/22 ATQ as well as a supporting study with Amines, Coco alkyl (C12-18-(even numbered)-alkylamines). These studies conclusively show that DMA category members will be fast and effectively eliminated in the STP firstly by adsorption on particulate matter and secondly by immediate and effective biodegradation by more than 90% in the plateau phase.
Biodegradation in Surface water
In a reliable River Water Die Away test with the radio labelled structural analogues HYEQS at 22 °C, the first order rate constant for primary biodegradation was 1.13 day-1, and the rate constant for mineralization was 0.09 day-1. Within 21 days 80% evolved as CO2.
Biodegradation in Sediment
No studies in sediment are available but the half-life in soil (see IUCLID section 5.2.3) of 16.9 d at 12 deg C can be used instead.

Key value for chemical safety assessment

Half-life in freshwater:
14.8 d
at the temperature of:
12 °C
Half-life in freshwater sediment:
16.9 d
at the temperature of:
12 °C

Additional information

Biodegradation in Sewage Treatment Plants


The first key study was performed with DMA category member C12-14-DMA. Elimination in sewage treatment plants was determined with a non-adapted activated sludge mixed with inoculum from garden soil and surface water from River Alz, southern Germany (STP simulaton test, coupled units; OECD 303A adpoted 1981). In deviation from the guideline, no DOC concentrations were determined. The purpose of the measurement was to check the rate of elimination of the test item. Therefore only one model activated sludge plant was used. Test duration was limited to 6 days. Inoculation was made by introducing 3 litre of the composite inoculum with a dry matter content of 2 g/L in the aeration vessel, because of the short duration of the test. Due to these deviations, the study is rated as reliable with restrictions (RL2). The test item was tested in a concentration of 4-28 mg (test material) dissolved in drinking water, corresponding to a oxygen demand (COD) of 45-116 mg O2 /L. The elimination of the test item in the aerobic simulation test was followed by gaschromatographic analyses. The elimination (removal via biodegradation and via sorption) of the test item was between 98.80 and >99.99%. The test item strongly sorbs to sewage sludge. Biodegradation will occur in the dissolved as well as in the sorbed phase.


The second key study (RL 1, according to GLP) was performed according to OECD 303A with the structural analogue HYEQS. HYEQS is of high similarity to C12-14 DMA in that it has essentially the same alkyl chain distribution and – like DMA category members - two methyl substituents at the amino group. The only difference is an additional hydroxyethyl substituent at the amino group rendering it a quaternary amine being permanently positively charged. This is however a minor difference as due to protonation at environmentally relevant pH values also DMA category members are predominantly positively charged at the amino group (for details, see category document, chapter 2). HYEQS was continuously dosed into the activated sludge unit resulting in an influent concentration of 200 µg/L (137 µg/L C12 isomer, 50 µg/L C14 isomer). Influent and effluent concentration of HYEQS were measured daily using LC MS MS (LOQ C12 organic medium = 0.96 µg/L, C14 0.35 µg/L) including the sludge adsorbed fraction. Already one day after the start of the test the elimination of HYEQS was > 99.95% for C12 and 99.89% for C14. After 2d biodegradation of HYEQS was >99% (quantification of free and sludge adsorbed fraction). The biodegradation rate during the plateau phase was >99.9%.


The third key study (RL 1, according to GLP) was performed according to OECD 303A with the structural analogue C20/22 ATQ. C20/22 ATQ may be regarded as worst case for DMA category members due to its longer alkyl chain. A further difference is that it has – in addition to the two methyl substituents at the amino group inherent to all DMA category members - an additional methyl substituent at the amino group, rendering it a quaternary amine being permanently positively charged. This is however a minor difference as due to protonation at environmentally relevant pH values also DMA category members are predominantly positively charged at the amino group (for details, see category document, chapter 2). C20/22 ATQ was continuously dosed into the activated sludge unit resulting in an influent concentration of 300 µg/L (41 µg/L C20 isomer, 243 µg/L C22 isomer). Influent and effluent concentration of C20/22 ATQ were measured daily using LC MS MS (LOQ C20 influent= 4.1 µg/L, C22 24.3 µg/L; LOQ C20 effluent= 2.1 µg/L, C22 12.1 µg/L) including the sludge adsorbed fraction. Already one day after the start of the test the elimination of C20/22 ATQ was > 99% (C20 and C22 fraction). Biodegradation of C20/22 ATQ has started immediately and reached a maximum of 98% during the plateau phase (quantification of free and sludge adsorbed fraction). Biodegradation of the C20 fraction was 94-98% (median 96%) and of the C22 fraction 87-93% (median 91%).


A further (supporting study) Aerobic Sewage Treatment Plants Simulation test (according to OECD 303A, GLP, RL1) was conducted with the structural analogue Amines, Coco alkyl (C12-18-(even numbered)-alkylamines) (Akzo Nobel, 2002a,b). In part a) of the test, sludge and waste water was from a municipal STP, while in part b) these were from an industrial plant. CAS units were fed with primary settled sewage spiked with coco alkyl amine (57 mg/l), secondary activated sludge from the same plants was used as inoculum. Removal was measured as non purgeable organic carbon (NPOC). 14 measurements from day 3-23 resulted in mean removal percentages of 97±1% for the test with domestic wastewater and 98±2% for the test with industrial wastewater. During the last week, 5 GC/MS measurements of the components were conducted. The detection limit was 1 μg/l for the saturated C12, C14, C16, and C18 amine resp. 3 μg/l for the unsaturated oleylamine. Based on the measurements, removal percentages for coco amine of >99.98% (municipal) resp. 99.83% (industrial) were calculated.


It can be concluded that DMA category members can be eliminated fast and effectively in the STP, firstly by adsorption on particulate matter and secondly by immediate and effective biodegradation by more than 90% in the plateau phase. This means that adsorption does not impede biodegradation, which is confirmed by the tests on ready biodegradability and the simulation tests on biodegradation in soil.



Biodegradation in Surface water


A River Water Die Away test (key study) with the radio labelled structural analogue HYEQS (14C-KDB Base) was conducted equivalent to OECD 314D guideline (Biodegradation in Treated Effluent-Surface Water Mixing Zone; reliability category 1) at 22 °C. HYEQS is of high similarity to C12-14 DMA in that it has essentially the same alkyl chain distribution and – like DMA category members - two methyl substituents at the amino group. The only difference is an additional hydroxyethyl substituent at the amino group rendering it a quaternary amine being permanently positively charged. This is however a minor difference as due to protonation at environmentally relevant pH values also DMA category members are predominantly positively charged at the amino group (for details, see category document, chapter 2).


The rate and extent of both primary (loss of parent) and ultimate (mineralisation to CO2) biodegradation was determined in river water inoculated with both sewage effluent and activated sludge. A small portion of the activated sludge was adapted to the test material before the test. The test system consisted of: 89% river water, 10% sewage effluent, and 1% combined activated sludge liquor. Biodegradation was determined by Liquid Scintillation Counting of 14C-radiolabelled HYEQS for a test duration of 21 days.


HYEQS degraded rapidly with a half-life of 0.61 days for loss of parent. No parent compound remained by day 5. The half-life of mineralization was 7.7 days (CO2 evolved), and by day 21, 80% of the test substance had evolved as CO2. After 21 days, 0% remained as parent, 11.6% was present as metabolites, 8.4% was present in the solids, and 80% was evolved CO2. The first order rate constant for primary biodegradation was 1.13 day-1, and the rate constant for mineralization was 0.09 day-1. Thus, also for DMA category members rapid and ultimate biodegradation in surface waters is expected.



Biodegradation in Sediment


According Annex IX, Section 9.2.1.4 column 2 of the REACH Regulation 1907/2006/EC a Sediment simulation test needs not to be carried out if the substance is readily biodegradable. Thus, the biodegradation of DMA category members in sediment was not tested. Based on ECHA REACH Guidance on Information Requirements and CSA, R.16 Environmental Exposure Assessment, Section A.16-3.2.2 (February 2016) a soil half-life may also be applied for aerobic sediment if no other data are available. A median (3 soils) half-life of 8.9 d at 20 degree C for soil was derived from an OECD 307 Aerobic Soil transformation study (see IUCLID Section 5.2.3) performed with the structural analogue hexadecanamine which will be used for sediment assessment.