Fatty acids, C5-10, esters with pentaerythritol

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06.06.-04.07.2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: From the aeration tank of a municipal sewage treatment plant, ARA Werdhölzli, 8048 Zürich, Switzerland
- Pretreatment: No

Duration of test (contact time):

28 d

Initial conc.:

22.1 mg/L

Based on:

other: TOC

Initial conc.:

21.8 mg/L

Based on:

other: TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Aerobic mineral salts medium, prepared with deionised water
- Test temperature: 22.0 ± 0.5 °C
- pH: 7.4 ± 0.2
- pH adjusted: yes with NaOH or H2SO4
- Aeration of dilution water: with CO2-free air
- Suspended solids concentration: 30 mg/L

TEST SYSTEM
- Culturing apparatus: 2500 mL glass bottles containing 2000 mL test solution;
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aerated with CO2-free air and fitted to gas-absorbtion bottles containing 125 ml of 0.15 M NaOH
- Measuring equipment: Shimadzu 5050 TOC-Analyzer using the NPOC-mode

SAMPLING
- Sampling frequency: Day 0, 1, 3, 7, 10, 14, 17, 21, 24 and 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates

Reference substance:

benzoic acid, sodium salt

Remarks:

20.0 mg/L (TOC)

Key result

Parameter:

% degradation (CO2 evolution)

Value:

96

Sampling time:

28 d

Results with reference substance:

The reference substance was degraded to 96.9% by 14 day.

The test substance is readily biodegradable under conditions tested. The biodegradation was > 60% within 28 days and reached 84% at the end of the 10 -day-window.

Table 1: Percentage biodegradation of test and reference substance

Day	Test substance (% degradation)	Reference substance (% degradation)
0	0.0	0.0
1	0.6	4.6
3	5.3	45.2
7	52.1	81.2
10	71.5	92.8
14	86.6	96.7
17	91.7	97.6
21	93.1	98.0
24	96.3	97.8
28	96.0	96.9

 

 

 

Interpretation of results:

readily biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

03.11.-01.12.2008

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:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge from the aeration basin of the domestic sewage treatment plant in 67435 Neustadt/Weinstraße, Lachen-Speyerdorf, Germany
- Preparation of inoculum for exposure: aerated continually, washed with and re-suspended in mineral medium

Duration of test (contact time):

28 d

Initial conc.:

25.9 mg/L

Based on:

test mat.

Initial conc.:

24.8 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium as described in OECD guideline
- Test temperature: 22 ± 1°C
- Suspended solids concentration: 25,1 mg/l

TEST SYSTEM
- Culturing apparatus: 2000 mL Schott flasks
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aerated with purified CO2 scrubbed, moistened air (bubbling the purified air through a flask containing 1.5M NaOH)
- Details of trap for CO2 and volatile organics if used: trapped in 0.25 M NaOH (scrubber containing 100 mL)

SAMPLING
- Sampling frequency: Day 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29
- Sampling method: Analyses of the emitted CO2 were made by IC measurement of samples from the front scrubber flask using a TOC multi N/C
2100S, Analytik Jena. Sample volume was 1 ml. On day 29, samples from both absorber bottles were taken.
- Other: On day 28, 5 mL HCl2 were added to all flasks to drive off dissolved CO2 into the absorber flask.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates
- Toxicity control: 1 replicate
- other: Abiotic control: 1 poisoned flask containing test item without inoculum

Reference substance:

aniline

Remarks:

25.2 mg/l

Key result

Parameter:

% degradation (CO2 evolution)

Value:

78

Sampling time:

28 d

Results with reference substance:

The reference substance was degraded to 100% by day 14.

The test substance is readily biodegradable under conditions tested. The biodegradation was 78% after 28 days and the 10-day-window was fulfilled. The 10 -day-window began on day 3 and at its end 63% were reached.

The IC content of test item in medium was higher then demanded in the guideline. This due to the fact of the test item is very poorly soluble in water. But the measured total carbon content corresponds to 4,61% of nominal TC. Therefore the result is considered valid.

Table 1: Percentage biodegradation of test substance, positive control, abiotic control and toxicity control

Day	Test substance (% degradation)	Positive control (% degradation)	Abiotic control (% degradation)	Toxicity control (% degradation)
2	4.6	4.3	0.9	2.6
4	22.4	34.7	0.5	27.3
7	44.4	62.7	-0.6	43.4
9	49.7	75.5	-1.2	58.6
11	58.8	77.7	-1.9	62.4
14	68.2	91.4	-2.5	83.1
18	75.9	96.2	-3.7	82.7
23	71.9	83.9	-4.4	73.3
29	78.4	75.9	-4.3	80.7

 

 

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable: 78 - 96 % (CO2 evolution) after 28 d (OECD 301B)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Two studies, investigating the ready biodegradability of pentaerythritol tetraesters of n-decanoic, n-heptanoic, n-octanoic and n-valeric acids (CAS-No. 68424-31-7) according to OECD 301B (CO2 Evolution Test), are available. In both studies domestic activated sludge (non adapted) was used as inoculum. In the key study (Häner, 2006) a mean degradation of 96% and in the supporting study (Muckle, 2009) of 78% could be observed at test termination after 28 days. In both studies the 10-day-window was reached. Therewith the test substance can be classified as readily biodegradable according to OECD criteria.