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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:
19.02.2018 - 21.03.2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Deviations:
no
GLP compliance:
no
Remarks:
accredited by DAkkS
Specific details on test material used for the study:
The test item is methylhydroquinone (CAS-No.: 95-71-6) with a purity of >99 %.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial, non-adapted
Duration of test (contact time):
28 d
Key result
Parameter:
% degradation (DOC removal)
Value:
33
Sampling time:
28 d

Table 1: DOC-content of blank value-samples and samples with methylhydroquinone, calculated mean values and resulting difference as well as DOC-degradation within total test duration.

test duration [d]

DOC [mg/l] of methylhydroquinone samples

DOC [mg/l] blank samples

DOC-difference [mg/l]

Degradation DOC[%]

I

II

mean

I

II

mean

0

52,00

56,75

54,38

9,40

8,99

9,20

45,18

0

2

44,60

46,03

45,32

1,80

2,82

2,31

43,01

5

5

46,42

44,47

45,45

4,49

3,97

4,23

41,22

9

7

45,86

45,17

45,52

4,92

6,13

5,53

39,99

11

9

46,77

44,88

45,83

5,74

5,44

5,59

40,24

11

12

41,81

45,11

43,46

7,25

9,27

8,26

35,20

22

16

34,78

37,56

36,17

< 0,50

< 0,50

< 0,50

35,67

21

19

35,94

39,42

37,68

< 0,50

4,96

2,73

34,95

23

21

35,25

39,47

37,36

3,64

4,34

3,99

33,37

26

23

35,69

33,03

34,36

< 0,50

5,57

3,04

31,33

31

26

32,71

27,58

30,15

< 0,50

< 0,50

< 0,50

29,65

34

28

34,88

29,46

32,17

2,34

1,54

1,94

30,23

33


       

Validity criteria fulfilled:
yes
Remarks:
The reference samples biodegraded within 5 days to a degree of 88%. Abiotic control samples showed no DOC-degradation.
Interpretation of results:
not readily biodegradable
Conclusions:
Methylhydroquinone is not rapidly biodegradable.
Executive summary:

As a criterion for the classification as rapidly biodegradable a DOC-elimination of 70% of the test item within a 10 day-window during a total test duration of 28 days is considered. The test samples of methylhydroquinone do not meet this criterion since only 33% DOC-elimination during the total test duration were attained. Hence, methylhydroquinone is classified as not rapidly biodegradable.

Description of key information

As a criterion for the classification as rapidly biodegradable a DOC-elimination of 70% of the test item within a 10 day-window during a total test duration of 28 days is considered. The test samples of methylhydroquinone do not meet this criterion since only 33% DOC-elimination during the total test duration were attained. Hence, methylhydroquinone is classified as not rapidly biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable
Type of water:
freshwater

Additional information