Fatty acids, C5-9, hexaesters with dipentaerythritol

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Study period:

16 Mar - 14 Apr 1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study with acceptable restrictions for a structurally similar substance, which feature similar physico-chemical properties, environmental behaviour and metabolism: No analytical purity given.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom, date of inspection 23 March 1998

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Melting point: < -20 °C
- Boiling point: 360 °C
- Vapour pressure: 5.4E-15 Pa at 25 °C
- Water solubility: < 0.0775 mg/L at 20 °C and pH 5.7
- log Pow: > 6.2 at 20 °C and pH 6.6

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: A mixed population of activated sludge microorganisms was obtained on 15 Mar 1999 from the aeration state of the Severn Trent Water Plc sewage treatment plant at Belper (Derbyshire, UK), which predominantly treats domestic sewage.
- Storage conditions: The sample of sludge was maintained on continuous aeration.
- Preparation of inoculum for exposure: The activated sludge was washed three times by settlement and resuspension. Approx. 24 h prior to the start of the test the inoculated culture medium was aerated overnight.

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

other: TOC

Initial conc.:

14.7 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: according to guideline
- Solubilising agent: granular silica gel, final concentration 33.3 mg/L
- Test temperature: 21 °C in temperature controlled room
- Aeration: CO2 free air at approx. 40 mL/min, continuous stirring
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 5 L glass culture vessels each containing 3 L of solution
- Number of culture flasks/concentration: 2
- Measuring equipment: Samples were analysed for CO2 using an Ionics 1555B TOC analyser and a Dohrmann DC-190 TOC analyser.
- Details of trap for CO2: The CO2 produced by degradation was collected in two 500 mL Dreschel bottles containing 350 mL of 0.05 M NaOH. The CO2 absorbing solutions were prepared using purified degassed water.

SAMPLING
- Sampling frequency for the first absorber vessel: on days 0, 1, 2, 3, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 27, 28 and 29
- Sampling frequency for the second absorber vessel: on days 0 and 29
- Sample storage before analysis: instant analysis
- Other: On day 28 1 mL of concentrated HCl was added to each vessel to drive off any inorganic carbonates formed. The vessels were resealed, aerated overnight and the final samples taken from both absorber vessels on day 29.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 vessels
- Toxicity control: yes, 1 vessel
- Reference control: yes, 2 vessels

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

14

Sampling time:

28 d

Details on results:

The test substance attained 14% degradation after an test period of 28 days. Thus, the substances is not readily biodegradable according to OECD criteria.

Results with reference substance:

Sodium benzoate attained 100% degradation after 28 days confirming the suitability of the inoculum and test conditions.

The toxicity control attained 41% degradation after 28 days confirming that the test material was not toxic to the microflora in the sewage.

Validity criteria fulfilled:

yes

Interpretation of results:

other: poorly biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Study period:

21 May - 25 Jul 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP - Guideline study, tested with the source substance fatty acids C5-10 esters with Dipentaerythritol. According to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

test duration was 60 instead of 28 days

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

yes (incl. QA statement)

Remarks:

(Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, Mainz, Germany)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge from a biological treatment plant at ESN, NW-Lachen-Speyerdorf, Germany.
- Laboratory culture: no
- Pretreatment: The sludge was filtrated, washed with tap water twice, then washed with and re-suspended in test medium. It was then aerated for >= 12 hours. The dry matter was determined with 4520 mg suspended solids/L.

Duration of test (contact time):

60 d

Initial conc.:

28.8 mg/L

Based on:

test mat.

Initial conc.:

29.3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: according to the guideline
- Test temperature: 19.8 - 22.5 °C
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 1500 mL flasks
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: The test vessels were aerated with purified CO2-scrubbed, moistened air. The scrubbing of carbon dioxide was achieved by bubbling the purified air through a flask containing 1.5 m NaOH. To control the absence of CO2, the air was then led through a flask containing a solution of Ba(OH)2 before reaching the test vessels.
- Measuring equipment: Carbon analyser TOC multi N/C 2100S, Analytik Jena
- Details of trap for CO2 and volatile organics if used: The emitted CO2 was trapped in 0.25 M NaOH. Two scrubbers containing 100 mL each were connected in series to the test vessels. The initial IC value of the 0.25 M NaOH was separately determined in each flask.

SAMPLING
- Sampling frequency: from each flask samples were taken on day 0, 2, 4, 7, 9, 11, 14, 18, 29, 35, 42, 49, 56 and 60
- Sampling method: From each scrubber flask, fifteen samples were taken in order to determine the emitted CO2. The sample volume was 1 mL. The resulting change in the volume of the front flask was considered in the calculation of emitted CO2. On day 59, 5 mL 2M HCL. were added to each flasks in order to drive off dissolved CO2. On day 60, samples from both scrubber test flask were taken.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 replicates
- Abiotic sterile control: yes, 1 bottle
- Toxicity control: yes, 1 bottle
- Posivite control: yes, 2 replicates

Reference substance:

aniline

Remarks:

(nominal concentration: 2.1 g/L)

Parameter:

% degradation (CO2 evolution)

Value:

29

Sampling time:

60 d

Remarks on result:

other: mean from two replicates

Details on results:

The test substance reached 29% degradation after 60 d. Therefore, the test item was considered to be not ready biodegradable according to OECD criteria.

Results with reference substance:

Degradation: 84.8% after 14 days, 60% pass level was reached.

The degradation behavior of positive control and toxicity control was normal. Abiotic degradation was not observed. Both replicates of the test item showed very good correspondence. If degradation in the flask is below 25% after 14 days, the test item can be considered as toxic towards the inoculum. As degradation in the toxicity flask was 48% after 14 days, the test item can be stated as “not toxic towards the inoculum in a concentration of 29.6 mg/L”.

Degradation values: % degradation of the test substance, reference substance, abiotic control and toxicity control.

Day	Positive control 1	Positive control 2	Positive control mean	Test 1	Test 2	Test mean	Abiotic control	Toxicity control
2	2.0	-0.3	0.8	0.8	0.7	0.8	1.7	-0.7
4	17.8	25.7	21.7	2.5	1.0	1.8	1.7	12.4
7	47.8	51.9	49.9	5.1	3.7	4.4	2.0	26.7
9	68.6	68.4	68.5	8.1	4.0	6.1	2.4	32.3
11	78.6	72.3	75.4	11.3	6.8	9.1	1.1	40.7
14	89.1	80.5	84.8	13.7	9.2	11.5	4.9	47.9
18	81.7	80.5	81.1	18.1	9.7	13.9	0.6	49.0
23	92.7	86.3	89.5	18.2	14.8	16.5	-0.1	51.1
29	91.3	83.6	87.4	25.2	17.7	21.5	-0.2	58.3
35	75.6	73.6	74.6	26.6	18.6	22.6	-1.6	44.6
42	81.7	77.2	79.4	30.4	22.4	26.4	-1.4	54.3
49	78.0	77.9	77.9	27.1	19.6	23.3	-2.5	53.2
56	79.0	77.4	78.2	30.7	23.6	27.1	-3.3	53.8
60	86.7	79.4	83.0	34.8	24.0	29.4	-3.3	54.7

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable, not fulfilling specific criteria

Description of key information

Not readily biodegradable: 29% (CO2 evolution) after 60 d (OECD 301B)
14% (CO2 evolution) after 28 d (OECD 301B)

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

In accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read across to the two structurally most similar analogue substancesfatty acids, C5-10, esters with dipentaerythritol (CAS 70983-72-1) and dipentaerythritol with fatty acids, C5 and C9iso (CAS 647028-25-9) was conducted to fulfil the data requirementsaccording to Annex VII-IX ofcarboxylic acids, C5-9, hexaesters with dipentaerythritol (CAS 67762-52 -1) in regard to biodegradation behaviour.

This read-across is justified in detail in the overall summary (IUCLID section 5) and within the analogue justification in IUCLID section 13. Both substances have got the same alcohol component (dipentaerythritol) and similar fatty acid chain lengths (C5-9 for the target substance compared to C7-10iso and C5-9iso for the source substances, respectively).

The study with the read across fatty acids, C5-10, esters with dipentaerythritol (CAS 70983-72-1) was investigated according to OECD 301B under GLP conditions using activated sludge from a wastewater treatment plant as inoculum (Muckle, 2012). Activated sludge microorganisms were exposed to a test substance concentration of 29.05 mg/L (mean) under aerobic conditions for an extended duration of 60 d. The results indicated that the test substance reached a mean degradation of 29% after 60 days. Therefore, the test substance is not readily biodegradable according to the OECD criteria.

The second read across with dipentaerythritol with fatty acids, C5 and C9iso (CAS 647028-25-9) was performed according to OECD 301B under GLP conditions (Mead, 2000). The study was conducted using activated sludge from a sewage wastewater treatment plant as inoculum. Microorganisms were exposed to a test substance concentration of 14.7 mg/L under aerobic conditions for 28 days. The results indicated that the test substance reached a mean degradation of 14% after 28 days. Therefore, the test substance is not readily biodegradable according to the OECD criteria.

Based on the result from structurally related read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which are characterized by a similar structure, it can be concluded that carboxylic acids, C5-9, hexaesters with dipentaerythritol is not readily biodegradable according to OECD criteria.