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Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Refer to analogue justification document provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (O2 consumption)

Value:

94

Sampling time:

28 d

Interpretation of results:

readily biodegradable

Conclusions:

A degradation of 94 % was observed after 28 d. Therefore, the test item can be considered as ready biodegradable.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 Jun - 10 Jul 2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Basic data given (comparable to guidelines/standards)

Qualifier:

according to guideline

Guideline:

other: MARINE BODIS ISO/TC 147/SC 5/WG 4N 141

Qualifier:

equivalent or similar to guideline

Guideline:

other: ISO 10708

Principles of method if other than guideline:

Unlike similar screening tests for biodegradability in freshwater systems, thismethod uses natural seawater fortified with mineral nutrients and no innoculum is added in addition to the micro-organisms already present in the seawater. Results from this test are not to be taken as indicators for ready or ultimate biodegradability but serves only to provide a preliminary level of information on ready degradability in seawater.

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: natural seawater

Details on inoculum:

Unlike similar screening tests for biodegradability in freshwater systems, this method uses natural seawater fortified with mineral nutrients and no innoculum is added in addition to the micro-organisms already present in the seawater. The raw seawater used for this study was supplied by a submersible pump situated on Sutherland’s pier on the west side of Flotta in Scapa Flow. It is pumped continuously from a depth of two metres below low water spring tide level, before passing up 1.8 kilometres of plastic pipe to a 20,000 litre storage tank. Two smaller pumps move the water to three settlement tanks situated nine metres above floor level. The seawater temperature varies between 6º C in the winter and 14º C in the summer. The salinity is between 34‰ and 37‰. Five to seven days before test commencement, raw seawater passes by gravity through a 45 µm filter to the ageing tank. Collected on 06 June 2007.

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

other: BOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Natural seawater enriched with (in g/L):
KH2PO4: 8.5
K2HPO4: 21.7
Na2HPO4 x 2H2O: 29.92
NH4Cl: 0.5
CaCl2: 31.84
MgSO4 x 7H2O: 22.5
FeCl3 x 6H2O: 0.25
EDTA: 0.4
- Solubilising agent (type and concentration if used): In tests conducted with poorly soluble materials, an inert support medium is used to provide a large and controlled surface area: 1 g/bottle of chromatography silica powder containing 20 mg of ThOD/g test material/reference base fluid
- Test temperature: 19.3 - 20.2 °C
- Aeration of dilution water: yes; Saturation value for dissolved oxygen at normal atmospheric pressure: 7.45 mg/L; Total Oxygen Capacity: 26.64 mg Oxygen per test vessel

TEST SYSTEM
- Culturing apparatus: 270 (± 0.5) mL glass BOD bottles containing 180 mL test medium
- Number of culture flasks/concentration: 3
- Measuring equipment: Polarographic electrode
- Test performed in closed vessels due to significant volatility of test substance: yes


CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 replicates
- Toxicity control: 3 replicates
- Other: support medium blank: 3 replicates

Reference substance:

benzoic acid, sodium salt

Reference substance:

other: olefin oil

Parameter:

% degradation (O2 consumption)

Value:

45

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

73

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

85

Sampling time:

21 d

Parameter:

% degradation (O2 consumption)

Value:

94

Sampling time:

28 d

Details on results:

The test item biodegraded by 94% over 28 days and showed an inhibition of -7% to seawater bacteria. The Oxygen blank and reference oil degradation were within formal and informal limits of acceptability, respectively.

Results with reference substance:

The soluble reference material, sodium benzoate, degraded by more than 60% in the first fourteen days, indicating that the seawater used in the test contained a satisfactory population of viable bacteria.

Table: Average barometric pressure corrected dissolved oxygen concentrations (mg O2/L)

	Day
	0	7	14	21	28
Oxygen consumption blank	7.17	6.97	7.23	7.06	7.01
Support medium control	7.22	6.89	7.03	7.00	6.93
Sodium benzoate	7.26	3.31	6.32	6.72	6.63
Reference oil	7.20	6.90	5.97	6.44	6.59
Test item	7.44	4.59	5.74	6.38	6.58
Test item + sodium benzoate	7.34	4.07	2.06	4.90	6.19

Table: Sum of BOD (mg O2 per bottle)

	Day
	7	14	21	28
Sodium benzoate	13.73	17.14	18.42	19.83
Reference oil	0.26	4.98	7.30	8.84
Test item	8.94	14.54	17.10	18.70
Test item + sodium benzoate	10.87	30.27	38.38	41.42

Interpretation of results:

readily biodegradable

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

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
Vega version 1.1.4

2. MODEL (incl. version number)
Ready Biodegradability Model (IRFMN) v. 1.0.9

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.

Qualifier:

according to guideline

Guideline:

other: REACH Guidance on QSARs R.6

Principles of method if other than guideline:

- Software tool(s) used including version: Vega v1.1.4
- Model(s) used: Ready biodegradability model (version 1.0.9)

Full reference and details of the used formulas can be found in:
Meylan W.M., Howard P.H., Boethling R.S. et al. Improved Method for Estimating Bioconcentration / Bioaccumulation Factor from Octanol/Water Partition Coefficient. 1999, Environ. Toxicol. Chem. 18(4): 664-672

- Model description: see field 'Justification for non-standard information', 'Attached justification' and 'any other information on Material and methods'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Remarks on result:

other: the substance was predicted to be readily biodegradable

For detailed information on the results please refer to the attached report.

Interpretation of results:

readily biodegradable

Reference 4

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Remarks:

The substance is not fully compliant with the applicability domain of the model. However, this calculation is used in a weight of evidence approach, in accordance to the REACh Regulation (EC) No 1907/2006, Annex XI General rules for adaptation of the standard testing regime set out in Annexes VII to X, 1.2. It is adequately documented and justified. For more detail see field `overall remarks, attachments´.

Justification for type of information:

1. SOFTWARE
Vega version 1.1.4

2. MODEL (incl. version number)
Ready Biodegradability Model (IRFMN) v. 1.0.9

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.

Qualifier:

according to guideline

Guideline:

other: REACH Guidance on QSARs R.6

Principles of method if other than guideline:

- Software tool(s) used including version: Vega v1.1.4

- Model(s) used: Ready biodegradability model (version 1.0.9)
Full reference and details of the used formulas can be found in:
Meylan W.M., Howard P.H., Boethling R.S. et al. Improved Method for Estimating Bioconcentration / Bioaccumulation Factor from Octanol/Water Partition Coefficient. 1999, Environ. Toxicol. Chem. 18(4): 664-672

- Model description: see field 'Justification for non-standard information', 'Attached justification' and 'any other information on Material and methods'

- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Remarks on result:

other: The substance was predicted to be possible readily biodegradable

For detailed information on the results please refer to the attached report.

Reference 5

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Remarks:

The substance is not fully compliant with the applicability domain of the model. However, this calculation is used in a weight of evidence approach, in accordance to the REACh Regulation (EC) No 1907/2006, Annex XI General rules for adaptation of the standard testing regime set out in Annexes VII to X, 1.2. It is adequately documented and justified. For more detail see field `overall remarks, attachments´.

Justification for type of information:

1. SOFTWARE
Vega version 1.1.4

2. MODEL (incl. version number)
Ready Biodegradability Model (IRFMN) v. 1.0.9

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.

Qualifier:

according to guideline

Guideline:

other: REACH Guidance on QSARs R.6

Principles of method if other than guideline:

- Software tool(s) used including version: Vega v1.1.4

- Model(s) used: Ready biodegradability model (version 1.0.9)
Full reference and details of the used formulas can be found in:
Meylan W.M., Howard P.H., Boethling R.S. et al. Improved Method for Estimating Bioconcentration / Bioaccumulation Factor from Octanol/Water Partition Coefficient. 1999, Environ. Toxicol. Chem. 18(4): 664-672

- Model description: see field 'Justification for non-standard information', 'Attached justification' and 'any other information on Material and methods'

- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Remarks on result:

other: The substance was predicted to be readily biodegradable.

For detailed information on the results please refer to the attached report.

Interpretation of results:

readily biodegradable

Description of key information

94% degradation (ISO 10708) after 28 days; read-across

Additional information

No study is available in which the ready biodegradability of Fatty acids, C16-18 (even numbered), esters with glycerol oligomers was assessed. Therefore, read-across to the structurally and chemically closely related source substance Fatty acids, C16-18, tetraesters with 3,3'-oxybis[1,2-propanediol] (CAS 91050-80-5) was performed in accordance with Regulation (EC) No 1907/2006 Annex XI, section 1.5 in order to fulfill the data requirements. The source substance is characterized by similar physico-chemical parameters and is therefore considered suitable representative for the assessment of the ready biodegradability of the target substance. A read-across justification is provided in IUCLID section 13. The robustness of the endpoint is supported by QSAR calculations using the VEGA Ready Biodegradability Model.

One study investigating the ready biodegradability of Fatty acids, C16-18, tetraesters with 3,3'-oxybis[1,2-propanediol] (CAS 91050-80-5) is available. This study is a marine Bodis-test similar to ISO 10708 performed under aerobic conditions using natural seawater as inoculum. A mean biodegradation of 94% was observed after 28 d. Biodegradation in seawater is expected to be slower than that in tests with freshwater and activated sludge as inoculum. Therefore, substances that reach the pass level in a seawater biodegradation test similar to ISO 10708 may be regarded as readily biodegradable.

Based on the available result from a structurally related read-across substance (in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5), which is characterized by a similar ecotoxicological profile and comparable structure, and based on QSAR calculations (VEGA (1.1.4); Ready Biodegradability Model (v1.0.9)), it can be concluded that the target substance Fatty acids, C16-18 (even numbered), esters with glycerol oligomers is readily biodegradable.