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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From November 04, 2019 to February 03, 2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
yes
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: Dihua Sewage Treatment Plant treating predominantly domestic sewage (Taiwan)
Duration of test (contact time):
ca. 29 d
Initial conc.:
ca. 20 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
acetic acid, sodium salt
Remarks:
Sodium acetate anhydrous
Parameter:
% degradation (CO2 evolution)
Remarks on result:
other: Not readily biodegrable
Results with reference substance:
At Day 14 during the study, the biodegradation of reference substance was 88.84 %.

Table 1. The cumulative CO2 production and percentage biodegradation of control group, test group, reference group and toxicity group

Time

(Day)

Cumulative CO2 production (mg)

Percentage biodegradation (%ThCO2)

Control group

Test group

Reference group

Toxicity group

Test group

Reference group

Toxicity group

(1)

(2)

(1)

(2)

Mean

2

0.72

2.81

1.60

23.49

21.51

3.18

1.81

2.50

26.66

12.21

5

5.01

2.92

1.38

49.23

50.77

3.31

1.56

2.44

55.88

28.81

7

8.20

3.36

1.27

67.60

71.01

3.81

1.44

2.62

76.73

40.30

9

11.06

0.49

-1.60

73.54

76.95

0.56

-1.81

-0.62

83.47

43.67

14

15.57

1.60

-0.61

78.27

84.43

1.81

-0.69

0.56

88.84

47.92

19

23.10

2.42

0.33

81.62

89.76

2.75

0.37

1.56

92.65

50.95

23

31.57

4.40

1.10

84.70

94.60

5.00

1.25

3.12

96.14

53.70

28

38.94

6.82

2.97

86.79

99.33

7.74

3.37

5.56

98.52

56.38

29

41.75

7.98

3.24

87.62

100.49

9.05

3.68

6.37

99.45

57.04

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
According to OECD 301B test method, Everzol SR98 was not readily biodegradable.
Executive summary:

This test using the procedures outlined in the SuperLab Study Plan for M62-191000009001EN and OECD 301B (OECD, 1992). The results of this test for Everzol SR98 show that all validity criteria were met. Everzol SR98 was not be considered readily biodegradable under the test conditions.

Description of key information

Not readily biodegradable (OECD TG 301B).

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information

Difference of percentage biodegradation between two replicates of each group were less than 20% during the test. The percentage biodegradation of the reference group was not less than 60% ThCO2 on the 14th days and the cumulative amount of CO2 produced in control group was less than 70 mg/L. All test validity criteria were met. Table 1 showed that toxicity group was not less than 25 % ThCO2 occurred within 14 days. Therefore, the test substance exerted no inhibitory effect to the inoculum. The percentage biodegradation of Everzol SR98 was not achieve 60 % with following 10 days. Therefore, Everzol SR98 was not the readily biodegradable.