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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:
weight of evidence
Study period:
08 Nov - 06 Dec 1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: Circular on Test Methods of New Chemical Substances (Japan), biodegraadation test
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
other: mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment
Details on inoculum:
- Source of inoculum/activated sludge (location, sampling depth): location: 10 sites (4 sewage plants, 3 rivers, 1 lake and 2 bays) around Japan, sampling depth: return sludge in sewage plants, surface water and surface soil of foreshore
- Laboratory culture: Thirty minutes after stopping of aeration, discard about one third of the whole volume of supernatant and add an equal volume of a solution (pH adapted to 7.0 with NaOH) containing 0.1% each of glucose, peptone and potasium orthophosphate, to the settled material and re-commence aeration. This procedure was repeated once per day.
- Temperature: 25 ± 2 °C
- Storage conditions: appearance and general condition of sludge were observed with a light microscope, sediments, pH, temperature and dissolved oxygen
- Storage length: started to use: 15 Oct 1991
- Concentration of sludge: 5500 mg/L
- Water filtered: no
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Parameter followed for biodegradation estimation:
TOC removal
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
TEST CONDITIONS
- Composition of medium: recommended medium in the guideline
- Test temperature: 25 ± 1 °C
- Suspended solids concentration: 30 mg/L
- Continuous darkness: no data

TEST SYSTEM
- Culturing apparatus: closed oxygen consumption measuring machine
- Number of culture flasks/concentration: 1 (water + test substance), 3 (sludge + test sub.), 1 (sludge + reference sub.), 1 (sludge)
- Measuring equipment: Coulometer
- Details of trap for CO2 and volatile organics if used: soda lime

SAMPLING
- Sampling frequency: continuously until day 28
- Sterility check if applicable: no
- Sample storage before analysis: no data

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
Reference substance:
aniline
Key result
Parameter:
% degradation (O2 consumption)
Value:
67
Sampling time:
28 d
Remarks on result:
other: BOD/ThOD
Key result
Parameter:
% degradation (test mat. analysis)
Value:
94
Sampling time:
28 d
Details on results:
No 10-day window required. Substance was readily biodegradable.
Results with reference substance:
The oxygen consumption for aniline in the above used test system reached 58% and 75% degradation after 7 days and 14 days.

Table 1. Results of analysis for BOD, DOC and GC

 

water + test sub.

sludge + test sub.

Theoretical amount

sample No. 6

sample No. 3

sample No. 4

sample No. 5

BOD

mg

0

60.8

64.5

60.6

92.7

DOC

mgC

-

0.8

1.1

1.2

23.8

% (*1)

-

3

5

5

-

GC of C9H14O6

mg

30.4

2.1

0.0

3.0

30

% (*1)

101

7

0

10

-

(*1): Residue percentage = Residue amount (mg) / Theoretical amount (mg) x 100

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Since the test substance reached the pass level for OECD 301C (biodegradation is > 60% after 28 d, no 10-day window required) tetradecanoic acid, tetradecyl ester is readily biodegradable according to the OECD criteria.
Executive summary:

The present study was performed according to OECD 301C (GLP) under aerobic conditions using a mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment as inoculum. The tetradecyl myristate (CAS No 3234-85-3; 100 mg/L), a constituent of the registration substance, was degraded to and extent of 67% (BOD) after 28 d. Since the substance reached the pass level for OECD 301C (biodegradation is > 60% after 28 d, no 10-day window required) tetradecanoic acid, tetradecyl ester is readily biodegradable according to the OECD criteria.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
22 Oct - 19 Nov 1991
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
Please refer to cread across justification justification setcion 13.2

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Please refer to cread across justification justification setcion 13.2

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to cread across justification justification setcion 13.2

3. ANALOGUE APPROACH JUSTIFICATION
Please refer to cread across justification justification setcion 13.2

4. DATA MATRIX
Please refer to cread across justification justification setcion 13.2
Reason / purpose for cross-reference:
read-across source
Inoculum or test system:
other:
Key result
Parameter:
% degradation (O2 consumption)
Value:
75.3
Sampling time:
28 d
Key result
Parameter:
% degradation (test mat. analysis)
Value:
86
Sampling time:
28 d
Details on results:
No 10-day window required. Substance was readily biodegradable.
Results with reference substance:
The oxygen consumption for aniline in the above used test system reached 60% and 72% degradation after 7 days and 14 days.

The degradation in one replicate was below the pass level (51.56%). However, the mean biodegradation based on BOD was > 70%. Moreover, the primary degradation measured by HPLC was 83, 74 and 100% in the three test vessels supports the assumption that the substance is readily biodegradable according to the OECD criteria.

Table 1. Result of BOD, DOC and HPLC after 28 days

 

water + test sub.

sludge + test sub.

Theoretical Amount

sample No. 6

sample No. 3

sample No. 4

sample No. 5

BOD (*1)

mg

0.0

85.0

49.5

81.4

96.0

DOC

mg

0.0

1.1

0.5

1.0

24.4

HPLC

mg

30.2

5.0

7.7

0.0

30

% (*2)

101

17

26

0

-

(*1) (sludge + test sub.) was calculated by subtracting blank values.

(*2) Residue percentage was calculated as followed.

Residue percentage = Residue amount (mg) / Theoretical amount (mg) x 100

Validity criteria fulfilled:
no
Remarks:
Biodegradation in one replicate differed by more then 20%.
Interpretation of results:
readily biodegradable
Conclusions:
Readily biodegradable: 75.3% (BOD) after 28 d (OECD 301C)
Executive summary:

The present study with docosyl docosanoate (CAS No 17671-27-1), a structural analogue, was performed according to OECD 301C (GLP) under aerobic conditions using a mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment as inoculum with a test substance concentration of 100 mg/L (Ministry of Economy, Trade and Industry, Japan, 1992). A biodegradation of 75.3% (BOD) was observed after 28 d. Since the substance reached the pass level for OECD 301C (biodegradation is > 60% after 28 d, no 10-day window required) docosyl docosanoate is readily biodegradable according to the OECD criteria.

Description of key information

Readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Two GLP Guideline studies conducted according to OECD 301 C are available investigating the ready biodigradability of tetradecyl myristate (CAS 3234-85-3), a constituent of the registration substance, and docosyl docosanoate (CAS No 17671-27-1), a strcutural analogue.

1. Result of study with tetradecyl myristate:

The study was performed according to OECD 301C (GLP) under aerobic conditions using a mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment as inoculum. The test substance (100 mg/L) was degraded to and extent of 67% (BOD) after 28 d. Since the substance reached the pass level for OECD 301C (biodegradation is > 60% after 28 d, no 10-day window required) tetradecanoic acid, tetradecyl ester is readily biodegradable according to the OECD criteria.

2. Result with dodesyl docosanoate:

The study with docosyl docosanoate was performed according to OECD 301C (GLP) under aerobic conditions using a mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment as inoculum with a test substance concentration of 100 mg/L (Ministry of Economy, Trade and Industry, Japan, 1992). A biodegradation of 75.3% (BOD) was observed after 28 d. Since the substance reached the pass level for OECD 301C (biodegradation is > 60% after 28 d, no 10-day window required) docosyl docosanoate is readily biodegradable according to the OECD criteria.

Based on the results from one constituent and one structural analogue of the registration substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) it can be concluded that cocoyl olivate is readily biodegradable according to the OECD criteria.