Fatty acids, C16-18, isononyl esters

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)

Remarks:

Summary of available data used for the endpoint assessment of the target substance.

Adequacy of study:

key study

Justification for type of information:

Refer to read across justification in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (CO2 evolution)

Value:

>= 76 - <= 81

Sampling time:

28 d

Remarks on result:

other:

Remarks:

Source: CAS 85049-37-2, Oleon, 1995, CO2 evolution

Parameter:

% degradation (CO2 evolution)

Value:

86.8

Sampling time:

28 d

Remarks on result:

other:

Remarks:

Source: CAS 26399-02-0, Croda, 1994, CO2 evolution

Interpretation of results:

readily biodegradable

Conclusions:

The substance is readily biodegradable according to OECD criteria.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: activated sludge plant secondary effluent

Details on inoculum:

- Source of inoculum/activated sludge: 10% by volume of activated sludge plant secondary effluent, filtered through Whatman filter paper (541)

Duration of test (contact time):

28 d

Initial conc.:

10.3 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral salts medium
- Test temperature: 20°C
- pH: 6.5 (adjusted)

TEST SYSTEM
- Culturing apparatus: 160 mL hypovials, 100 mL fill volume
- Number of culture flasks/concentration: 12
- Measuring equipment: Inorganic Carbon Analyser (Ionics 555)
- Test performed in open system: no, sealed with rubber septum and aluminium crimp seal
- Details of trap for CO2 and volatile organics if used: headspace gas

SAMPLING
- Sampling frequency: Day 4, 7, 11, 14, 18, 21 and 28
- Sampling method: One vessel per substance and control on every day, but day 28 (where 5 vessels were analysed)

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

86.8

Sampling time:

28 d

Remarks on result:

other: 84.0-89.7 (95% C.L.)

Details on results:

The test substance reaches a biodegradation of 86.8% within 28 days. As the 10-day window is passed the substance can be judged readily biodegradable according to OECD criteria.

Results with reference substance:

Reference substance was 89.8% biodegraded in 28 days, and fulfilled the 10-day window criteria

Degradation: 34.3% day 4, 61.1% day 7, 76.2% day 11, 75.7% day 14, 84.2% day 18, 85.3% day 21 and 86.8% day 28

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 Jul - 14 Aug 1995

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge was obtained from aeration tank of the waste water treatment plant of Bocholt (Germany), which predominantely treats domestic sewage.
- Pretreatment: Sludge is aerated for 4 hours. Then 3 L of the mixed liquor is homogenised and allowed to settle for 30 minutes. The clear supernatant is decanted to provide sufficient volume for a 1% inoculum in each carboy.

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: according to guideline
- Test temperature: 21 - 24 °C
- pH: 6.97 - 7.41

TEST SYSTEM
- Culturing apparatus: 5 L brown bottle with aeration tubes
- Number of culture flasks/concentration: 2
- Details of trap for CO2 and volatile organics if used: An empty glass bottle to prevent carry-over, a 1 L glass bottle containing 700 mL of 10M NaOH, a 1 L glass bottle containing 700 mL 0.0125 M Ba(OH)2 x 8H2O and an empty glass bottle are connected in series to a pressurised air source.

SAMPLING
- Sampling frequency: Samples were taken on day 1, 3, 5, 7, 10, 14, 18, 24 and 28.
- Sampling method: Periodically, the CO2-absorber closest to the carboy is removed for titration. The remaining absorber is moved one position closer to the carboy and a new absorber is placed at the far end of the series.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 replicates

Reference substance:

aniline

Parameter:

% degradation (CO2 evolution)

Value:

>= 76 - <= 81

Sampling time:

28 d

Details on results:

The test substance reached a biodegtradation of 76 - 81% within a test period of 28 days. As the pass level of 60% was reached in a time period of 10 days, the substance can be judged as readily biodegradable.

Results with reference substance:

80% biodegradation after 28 days

Table 1: Biodegradability of reference (test validity) and test substance in %:

	Biodegradability in %	Biodegradability in % (1)	Biodegradability in % (2)
Day	aniline	CAS No. 85049-37-2	CAS No. 85049-37-2
1	0.3	0.2	0.3
3	1.8	9.9	14.5
5	26.0	31.9	36.6
7	49.0	48.9	54.4
10	63.2	60.8	65.1
14	71.5	70.5	73.1
18	73.6	73.0	77.2
24	76.8	74.3	79.9
28	78.5	75.6	80.9
28*	79.8	75.9	81.4

* after addition of 1 ml HCl to drive off inorganic carbonate

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Reference 4

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

(Q)SAR

Adequacy of study:

supporting study

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 1.1.3

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.

Principles of method if other than guideline:

- Software tool(s) used including version: Vega v1.1.3

- 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

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks on result:

other:

Remarks:

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

Conclusions:

The substance was predicted to be readily biodegradable, according to the Ready Biodegradability model (IRFMN) 1.0.9 and the result appears to be reliable.

Description of key information

Readily biodegradable: 76 – 86.8% within 28 d (301 B, activated sludge); read-across

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

There are no studies available assessing the ready biodegradability of the target substance Fatty acids, C16-18, isononyl esters (CAS 91031-57-1). Therefore, read-across to the two structurally and physico-chemically related source substances Fatty acids, C16-18 and C18-unsatd., 2-ethylhexyl esters (CAS 85049-37-2) and 2-ethylhexyl oleate (CAS 26399-02-0) was conducted in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5. A detailed read-across justification is provided in IUCLID section 13. The biodegradation of the target substance is further supported by reliable QSAR calculations.

Both available read-across studies assessed the ready biodegradability in a CO2 evolution test according to OECD 301 B and GLP.

In the study with source substance Fatty acids, C16-18 and C18-unsatd., 2-ethylhexyl esters (CAS 85049-37-2), a concentration of 10 mg/L test item (nominal, DOC) was inoculated with non-adapted domestic activated sludge and monitored for 28 days. After 28 days, 76 to 81% of the initial test substance was degraded (10-day window was met). Based on these findings, the substance fatty acids, C16-18 and C18-unsatd., 2-ethylhexyl esters is considered to be readily biodegradable according to the OECD criteria.

In the study with 2-ethylhexyl oleate (CAS 26399-02-0) 10.3 mg/L test item (organic carbon content) was inoculated with activated sludge and monitored for 28 days. After 28 days, 86.8% of the initial test substance was degraded. Based on these findings, the substance 2-ethylhexyl oleate is considered to be readily biodegradable according to the OECD criteria.

QSAR calculations (VEGA, IRFMN 1.0.9) predict that the two main constituents of the target substance are readily biodegradable. This result supports the experimental results obtained with the source substance. The prediction of the model is reliable and can thus be used for hazard assessment of the substance.

Based on the structural and physico-chemical similarity of the target and source substances, the results from the source substance can be used to assess the biodegradability of the target substance. In conclusion, the available data suggest that the target substance fatty acids, C16-18, isononyl esters (CAS 91031-57-1) is readily biodegradable.