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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:
08 December 1992 to 22 January 1993
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Study conducted on read-across material
Justification for type of information:
See the read-across report attached in Section 13.
Reason / purpose:
other: Read-across target
Related information:
Composition 1
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
no
GLP compliance:
no
Test material information:
Composition 1
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: Standard activated sludge was obtained from Chemicals Inspection & Testing Institute.
- Preparation of inoculum for exposure: The standard activated sludge was suspended in ion exchange water and centrifuged. Washing was repeated three times.
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: See the field “Any other information on materials and methods incl. tables”
- Concentration of activated sludge: 30 mg/L (as dry weight)
- Test temperature: 25 ± 1 °C
- Continuous darkness: Yes

TEST SYSTEM
- Number of culture flasks/concentration: Duplicate flasks
- Measuring equipment: Oxygen consumption was continuously measured by BOD measuring equipment
- Measurement conditions: Measurement range, 250 ppm (full scale, 100 % = 75 mgO); Chart speed, 3.125 mm/h; Volume of incubation liquid, 300 mL.
- Test performed in closed vessels: Yes, the inoculum was incubated by stirring in a closed system

SAMPLING
- Sampling frequency: All test systems were measured after Day 7, 14, 21 and 28.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Activated sludge + culture medium
- Abiotic sterile control: Test material + ion exchange water
- Reference substance: Aniline + activated sludge + culture medium
- Sludge blank: Activated sludge + culture medium
Reference substance:
aniline
Remarks:
100 mg/L
Parameter:
% degradation (O2 consumption)
Value:
74.4
Sampling time:
28 d
Results with reference substance:
The degree of degradation in the aniline treated test system was > 40% after 7 days, confirming that the test system was valid.

Table 1: Degree of Biodegradation (%)

Test System

After Day 7

After Day 14

After Day 21

After Day 28

After Day 28

(average)

Test Material, Replicate A

62.3

67.9

75.4

79.3

74.4

Test Material, Replicate B

62.3

70.7

72.6

72.6

Abiotic Sterile Control

58.6

62.3

65.1

67.0

-

Reference Substance*

66.6

78.4

89.0

95.3

-

* Aniline

Table 2: BOD and TOD Values for the Added Amount of Test Material and Aniline (mgO)

Test System

After Day 7

After Day 14

After Day 21

After Day 28

TOD Value

Test Material, Replicate A

27.8

33.8

39.4

42.0

40.3

Test Material, Replicate B

27.8

34.9

38.2

40.5

40.3

Abiotic Sterile Control

23.6

25.1

26.2

27.0

40.3

Reference Substance*

66.0

81.0

93.8

102.0

95.2

Inoculum Blank

2.6

6.4

9.0

11.2

-

* Aniline

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Under the conditions of the study, the test material degraded by 74.4 % after 28 days and was determined to be readily biodegradable.
Executive summary:

The biodegradation of the test material was determined in a ready biodegradability (modified MITI Test (I)) performed according to the OECD guideline 301.C. Standard activated sludge was used as the source of microorganisms, and biochemical oxygen demand (BOD) was continuously measured by closed system automatic measuring equipment of consumed oxygen. Under the conditions of the test, the test material degraded by 74.4% after 28 days and was determined to be readily biodegradable.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted on read-across material
Justification for type of information:
RAAF report to be provided.
Reason / purpose:
read-across source
Related information:
Composition 1
Reference:
Composition 0
Test material information:
Composition 1
Key result
Parameter:
% degradation (O2 consumption)
Value:
74.4
Sampling time:
28 d

Description of key information

Read-across to a substance with a similar structure.

Readily Biodegradable, 74.4 % after 28 days, OECD 301 C, Yoshikawa (1993).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Read-across to a substance with a similar structure.

The key study Yoshikawa (1993) is a non-GLP study yet was conducted in accordance to the standardised guideline the OECD 301.C. The original full study report is in Japanese and has been translated into English. Sufficient details were reported to assess the quality of the submitted results; the study has been assigned a reliability score of 2 in line with the principles for assessing data quality as defined by Klimisch (1997).

The biodegradation of the test material was determined in a ready biodegradability (modified MITI Test (I)) performed according to the OECD guideline 301.C. Standard activated sludge was used as the source of microorganisms, and biochemical oxygen demand (BOD) was continuously measured by closed system automatic measuring equipment of consumed oxygen. Under the conditions of the test, the test material degraded by 74.4% after 28 days and was determined to be readily biodegradable.