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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:
1997-01-16 - 1997-02-13
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
Method of the Directive 67/548/EEC Annex V.C.4-D (Manometric Respirometry), 1992
Deviations:
no
GLP compliance:
no
Specific details on test material used for the study:
Not applicable.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from wastewater treatment plant, operated with communal waste water (Wupperverband, Germany).
- Storage length: 1 day (sampling date: 1997-01-15)
- Preparation of inoculum for exposure: not specified
- Concentration of sludge: 30 mg/L suspended solids
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 temperature: 20 +/- 1 °C
Reference substance:
aniline
Preliminary study:
No preliminary study was reported.
Test performance:
The test substance is directly weighed out into a mineral medium, inoculated with an aquatic mix population of microorganisms and incubated for 28 days (aerob in the dark at 20 +/- 1 °C). The biodegradation of the test substance during this time is determined by using a respirometer, which records the oxygen consumption.
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
4 d
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
14 d
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Details on results:
The toxicity control attained 39 % degradation after 28 days, confirming that the test substance in the used concentration was not bacteriotoxic.
Parameter:
COD
Value:
1 820 mg O2/g test mat.
Results with reference substance:
Aniline is biodegraded 77 % after 14 days, 81 % on day 28.

Table 1: Summary of measured values

Cell flask content BSB in [mg O2/L] after following days
4 6 8 12 14 18 20 22 26 28
37 Test substance a1 7 7 7 7 7 7 7 7 7 7
38 Test substance a2 6 6 6 6 6 6 6 6 6 6
39 Test substance a3 8 8 8 8 8 8 8 8 8 8
1 Blank b1 14 15 17 19 19 19 19 19 19 19
2 Blank b2    10 12 12 15 15 15 15 15 15 15
3 Blank b3  16 18 20 24 25 26 27 28 29 30
Mean bm   13 15 16 19 20 20 20 21 21 21
4 Anilin r1 8 10 49 199 208 218 221 223 226 227
5 Anilin r2  3 5 87 196 202 206 206 206 206 206
6 Anilin r3 6 6 30 191 202 211 213 214 215 216
40 Toxicity Control T1 2 70 131 153 157 165 176 172 184 176
41 Toxcity Control T2  4 43 143 166 169 168 181 176 191 193

Study Results

Test substance

Initial concentration: 100 mg/L

COD: 1820 mg O2/g

Table 2: Test substance results

 Duration (days)    4 6  8  12  14  18  20  22  26  28
 O2 consumption (g O2/L)  a1  0  0  0  0  0  0  0  0  0  0
 a2  0  0  0  0  0  0  0  0  0  0
 a3  0  0  0  0  0  0  0  0  0
 % Degradation        a1  0  0  0  0  0  0  0  0  0  0
 a2  0  0  0  0  0  0  0  0  0  0
 a3  0  0  0  0  0  0  0  0  0  0
 % Degradation (Mean)    0  0  0  0  0  0  0  0  0  0

Reference substance

Initial concentration: 100 mg/L

Molecular formula: C6H7N

Molecular weight: 93.129 g/mol

ThOD: 2409 mg O2/g

Table 3: Reference substance results

Duration (days)    4 6  8  12  14  18  20  22  26  28
 O2 comsumption (g O2/l)  r1  0  0  33  180  188  198  201  202  205  206
 r2  0  0  71  177  182  186  186  185  185  185
 r3  0  0  14  172  182  191  193  193  194  195
 % Degradation        r1  0  0  14  75  78  82  83  84  85  86
 r2  0 0  29  73  76  77  77  77  77  77
 r3  0  0  6  71  76  79  80  80  81  81
 % Degradation (Mean)    0  0  16  73  77  79  80  80  81  81

Note: The calculation of degradation was carried out under the assumption that no nitrogen oxidation takes place.

Toxicity Control

Initial concentration: 100 mg/L

Initial concentration test substance: 100 mg/L

ThOD of reference substance: 2409 mg O2/g

COD of test substance: 1820 mg O2/g

Table 4: Toxicity control results

Duration (days)    4 6  8  12  14  18  20  22  26  28
O2 consumption (mg O2/L)  t1  55  115  134  137  145  148  151  155  155
 t2  0  28  127  147  149  156  161  163  170  172
 % Degradation     t1  0  13  27  32  32  34  35  36  37  37
 t2  7  30  35  35  37  38  39  40  41
 % Degradation (Mean)    0  10  29  34  34  36  37  38  39  39

Note: The test substance was not bacteriotoxic in the used concentration.

Validity criteria fulfilled:
yes
Remarks:
Validity criteria according to EU Method C.4-D are fulfilled.
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
The study was performed according to EU Method C.4 (Manometric respirometry test) without deviations which may have an impact on the validity of the study. Thus, the results were obtained via a scientifically reasonable method. Hence, there is no doubt that the obtained results are not reliable. Under the conditions used for the test, no degradation has occured during the test duration of 28 days (0 %). Accordingly, the test substance can be regarded as 'not readily biodegradable'.
Executive summary:

The biodegradability of the test substance was investigated according to EU Method C.4 -D (Manometric Respirometry Test). No GLP compliance was cited but the test facility is known to work under standard good laboratory practice. Activated sludge (adaption not further specified) taken from a domestic source with a concentration of 30 mg/L suspended solids is used as inoculumn. The test substance with an initial concentration of 100 mg/L is weighted in a mineral medium containing the inoculumn and incubated for 28 days under aerobic conditions in the dark at 20 ± 1 °C. In parralell the reference substance aniline and a toxicity control are tested, both at a concentration of 100 mg/L also. The biodegradability was determined by means of a respirometer recording oxygen consumption. Based on these measurements 77 and 81 % of the reference degraded after 14 days and 28 days, respectively. In contrast the test substance showed no degradation (0 %) after 4, 14 and 28 days. Accordingly, the test substance can be regarded to be "not readily biodegradable". Based on the results of the toxicity control, the test substance was determined to be not bacteriotoxic .

Endpoint:
biodegradation in water: screening tests
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
12 June 2020
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
Estimation Programs Interface (EPI) Suite for Microsoft Windows, v4.11 (US EPA, 2012)

2. MODEL (incl. version number)
BIOWIN v4.10

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
CC(C)c1cc(C(C)C)c(N=C=O)c(C(C)C)c1N=C=O

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF.

5. APPLICABILITY DOMAIN
See attached QPRF.

6. ADEQUACY OF THE RESULT
- The model is scientifically valid (see attached QMRF).
- See attached QPRF for reliability assessment.
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: EpiSuite v4.11
- Model(s) used: BIOWIN v4.10
- Model description: see field ''Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
Specific details on test material used for the study:
CC(C)c1cc(C(C)C)c(N=C=O)c(C(C)C)c1N=C=O
Oxygen conditions:
other: aerobic (Biowin 1-6) and anaerobic (Biowin 7)
Inoculum or test system:
other: QSAR estimation
Details on study design:
Using the computer tool BIOWIN v4.10 by US-EPA (EPIWIN) the aerobic as well as the anaerobic biodegradability of the test material can be estimated. The following seven different models are used by the tool: Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called Biowin 1-7, respectively). Due to these results the overall prediction of readily biodegradability is done for the desired chemical.
Remarks on result:
not readily biodegradable based on QSAR/QSPR prediction
Details on results:
According to the Linear and also Non-linear Model the substance will biodegrade fast. The Ultimate Biodegradation Timeframe is given in weeks till months, and the Primary Biodegradation Timeframe shows as result a time period of weeks. Both MITI Models predict that the substance is not readily biodegradable, which is also the overall prediction result. Also under anaerobic conditions the substance is suspected to be not biodegraded fast.

Table 1: Biodegradability prediction of 2,4,6-triisopropyl-m-phenylene-diisocyanate

Parameter

Method

Result

Ready Biodegradability Prediction

(withcomputer program from US-EPA (EPIWIN software: BIOWIN Program v4.10))

Biowin1:

Linear Model Prediction

Biodegrades fast

Biowin2:

Non-linear Model Prediction

Biodegrades fast

Biowin3:

Ultimate Biodegradation Timeframe

Weeks - Months

Biowin4:

Primary Biodegradation Timeframe

Weeks

Biowin5:

MITI Linear Model Prediction

Not readily degradable

Biowin6:

MITI Non-Linear Model Prediction

 Not readily degradable

Biowin7:

Anaerobic Model Prediction

Does not biodegrade fast

Ready Biodegradability Prediction

NO

 

Validity criteria fulfilled:
yes
Remarks:
scientifically accepted calculation method was used.
Interpretation of results:
not readily biodegradable
Conclusions:
The substance was predicted to be not ready bioegradable using the US-EPA software BIOWIN v4.10.
Executive summary:

The prediction for biodegradability of the test substance was determined by the computer program BIOWIN v4.10 (EPIWIN software) by US-EPA (2012). The program calculates with seven different models: Linear Model (Biowin 1), Non-linear Model (Biowin 2), Ultimate Biodegradation Timeframe (Biowin 3), Primary Biodegradation Timeframe (Biowin 4), MITI Linear Model (Biowin 5), MITI Non-linear Model (Biowin 6) and Anaerobic Model (Biowin 7). The overall result gives the ready biodegradability prediction of the desired compound. According to Biowin 1 and 2 the substance is biodegrading fast. The Ultimate Biodegradation Timeframe is given in weeks till months, and the Primary Biodegradation Timeframe gives weeks as result. Both MITI Models predict that the substance is not readily biodegradable, which is also the overall prediction result. Also under anaerobic conditions the substance is not expected to be degraded fast.

Description of key information

1) Key_Biodegradation in water: screening tests: The test substance showed 0% degradation after 4, 14 and 28 days of test duration and can therefore be considered to be "not readily biodegradable" (activated sludge, aerobic, EU Method C.4 -D)

2) Supporting_Biodegradation in water: screening tests_QSAR: BIOWIN v4.10 (EPIWIN software) by US-EPA (2012), overall prediction result = not readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
not biodegradable

Additional information

The biodegradability of the test substance was investigated according to EU Method C.4 -D (Manometric Respirometry Test). No GLP compliance was cited but the test facility is known to work under standard good laboratory practice. Activated sludge (adaption not further specified) taken from a domestic source with a concentration of 30 mg/L suspended solids is used as inoculumn. The test substance with an initial concentration of 100 mg/L is weighted in a mineral medium containing the inoculumn and incubated for 28 days under aerobic conditions in the dark at 20 ± 1 °C. In parralell the reference substance aniline and a toxicity control are tested, both at a concentration of 100 mg/L also. The biodegradability was determined by means of a respirometer recording oxygen consumption. Based on these measurements 77 and 81 % of the reference degraded after 14 days and 28 days, respectively. In contrast the test substance showed no degradation (0 %) after 4, 14 and 28 days. Accordingly, the test substance can be regarded to be "not readily biodegradable". Based on the results of the toxicity control, the test substance was determined to be not bacteriotoxic .

As supporting information a prediction for biodegradability of the test substance was determined by the computer program BIOWIN v4.10 (EPIWIN software) by US-EPA (2012). The program calculates with seven different models: Linear Model (Biowin 1), Non-linear Model (Biowin 2), Ultimate Biodegradation Timeframe (Biowin 3), Primary Biodegradation Timeframe (Biowin 4), MITI Linear Model (Biowin 5), MITI Non-linear Model (Biowin 6) and Anaerobic Model (Biowin 7). The overall result gives the ready biodegradability prediction of the desired compound. According to Biowin 1 and 2 the substance is biodegrading fast. The Ultimate Biodegradation Timeframe is given in weeks till months, and the Primary Biodegradation Timeframe gives weeks as result. Both MITI Models predict that the substance is not readily biodegradable, which is also the overall prediction result. Also under anaerobic conditions the substance is not expected to be degraded fast. This supports the study result that the test substance is "not readily biodegradable".