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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:
14 August 1995 to 31 October 1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study was conducted in accordance with generally accepted scientific principles, possibly with incomplete reporting or methodological deficiences which do not affect the quality of the relevant results.
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Version / remarks:
1992
Deviations:
no
GLP compliance:
not specified
Specific details on test material used for the study:
-Lot No.: 89002
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: Standard activated sludge (Chemicals Inspection & Testing Institute, obtained on July 20, 1995)- Source of inoculum/activated sludge: Standard activated sludge (Chemicals Inspection & Testing Institute, obtained on July 20, 1995)
- Preparation of inoculum for exposure: On the day of test start the standard activated sludge was suspended in ion exchanged water and centrifuged. This washing procedure was repeated 3 times to obtain activated sludge for addition.
Duration of test (contact time):
28 d
Initial conc.:
98 mg/L
Based on:
test mat.
Details on study design:
TEST CONDITIONS
- Composition of medium: Culture medium was prepared by adding 3 mL each of Liquid A, B, C, and D into 1L of ion exchanged water: A: 21.75 g of dipotassium hydrogen phosphate, 8.5 g of potassium dihydrogen phosphate, 44.6 g of disodium hydrogen phosphate 12 hydrate, and 1.7 g of ammonium chloride were dissolved in 1 L of water. B: 22.5 g of magnesium sulphate 7 hydrate was dissolved in 1 L of water. C: 27.5 g of calcium chloride (anhydrous) was dissolved in 1 L of water. D: 0.25 g of iron (III) chloride 6 hydrate was dissolved in 1 L of water.
- Test temperature: 25 ± 1 °C
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: Oxygen consumption was continuously measured by BOD measuring equipment
- Other: Stirring using stirrer
Key result
Parameter:
% degradation (O2 consumption)
Value:
65.8
Sampling time:
28 d

Table 1: BIODEGRADATION (%)

Test Segment

After 7 days

After 14 days

After 21 days

After 28 days

After 28 days (average)

Test material

 

 

 

 

 

Incubation test segment 1

57.4

59.0

58.0

59.6

 

Incubation test segment 2

48.5

63.2

62.6

62.6

65.8

Incubation test segment 3

59.0

63.6

68.5

75.3

 

Non-incubation test segment

<5

7.4

14.2

21.6

-

Aniline

 

 

 

 

 

Standard test segment

56.7

63.6

66.2

69.5

-

Table 2: BOD Value and ThOD Value for the Added Amount of Test Material and Aniline

Test Segment

After 7 days

After 14 days

After 21 days

After 28 days

ThOD

Test material

 

 

 

 

 

Incubation test segment 1

42.4

47.3

50.3

53.3

71.2

Incubation test segment 2

36.0

50.3

53.6

55.5

71.2

Incubation test segment 3

43.5

50.6

57.8

64.5

71.2

Non-incubation test segment

<2

5.3

10.1

15.4

71.2

Aniline

 

 

 

 

 

Standard test segment

52.9

63.0

69.0

73.9

90.7

Inoculation blank

<2

5.3

9.0

10.9

-

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Under the conditions of the study, the test material degraded by 65.8% after 28 days and was determined to be 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 65.8% after 28 days and was determined to be readily biodegradable.

Description of key information

Readily biodegradable, 65.8% after 28 days, OECD 301 C, Fujii 1995.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The key study (Fujii 1995) was performed to standardised guidelines with a sufficient level of detail to assess the quality of the submitted data. Sufficient details were reported to assess the quality of the submitted results. The study was 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 study, the test material degraded by 65.8% after 28 days and was determined to be readily biodegradable.