Decanoic acid, mixed esters with heptanoic acid, octanoic acid and trimethylolpropane

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions (no purity stated)

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 from the aeration basin of the domestic sewage treatment plant in Lachen-Speyerdorf, Germany (2008-05-08)
- Preparation of inoculum for exposure: The sludge was aerated continually, washed with and re-suspended in mineral medium.

Duration of test (contact time):

29 d

Initial conc.:

29.7 mg/L

Based on:

test mat.

Initial conc.:

31.9 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium according to OECD guideline
- Test temperature: 22 ± 1°C
- Aeration of dilution water: Before adding test and reference item, all flasks were aerated for > 24 h with purified, CO2-free, moistened air.
- Suspended solids concentration: 25 mg/L

TEST SYSTEM
- Culturing apparatus: 2000 mL-SCHOTT-flasks containing 1500 mL
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Aeration with purified, CO2-scribbed, moistened air. The scrubbing of carbon dioxide was achieved by bubbling the purified air through a flask containing 1.5-m-NaOH.
- Measuring equipment: TOC multi N/C 2100S, Analytik Jena for IC measurement
- Details of trap for CO2 and volatile organics if used: The emitted CO2 was trapped in 0.25-m-NaOH. Two scrubber containing 100 mL each were connected in series to the test vessels.

SAMPLING
- Sampling frequency: on day 0, 2, 4, 7, 9, 11, 14, 17, 23 and 29
- Sampling method: On day 28, 5 mL HCl 2-m were added to all flasks in order to end the test and to drive off dissolved CO2 into the absorber flasks. Analyses of the emitted CO2 were made by IC measurement of samples from the front scrubber flask. Sample volume was 1 mL. Each sample was measured at least in duplicate. On day 29 samples from both absorber bottles were taken.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, 2 replicates
- Abiotic control: Yes, 1 replicate
- Toxicity control: Yes, 1 replicate

Reference substance:

aniline

Remarks:

26.8 mg/L

Key result

Parameter:

% degradation (CO2 evolution)

Value:

85.3

Sampling time:

29 d

Details on results:

Within the 10-day time window the 60% level was passed. Therefore, the test substance is regarded as readily biodegradable.

Results with reference substance:

Degradation: 83.5% after 7 days, 60% pass level was reached.

Table 1: Degradation (%) of reference substance, test substance, abiotic control and toxicity control

Day	Reference 1	Reference 2	Reference Mean	Test 1	Test 2	Test Mean	Abiotoc control	Toxicity control
2	-0.1	-0.1	-0.1	1.5	2.0	1.7	0.2	1.3
4	56.0	45.3	50.6	24.6	21.4	23.0	0.2	41.8
7	86.5	80.5	83.5	45.0	51.9	48.5	0.5	65.9
9	89.8	82.5	86.2	57.9	56.2	57.0	-0.2	70.4
11	89.5	89.2	89.4	64.0	61.2	62.6	-0.7	74.4
14	88.9	91.0	89.9	67.9	63.8	65.8	0.3	80.4
17	88.4	86.5	87.4	74.8	65.8	70.3	-0.7	77.2
23	90.1	88.1	89.1	79.7	77.1	78.4	-2.5	84.3
29	89.3	90.6	89.9	84.1	86.4	85.3	-1.1	87.9

 

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 Jan - 20 Feb 2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study. For read-across, maximum reliability score is 2.

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide 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 tank of a municipal waste water treatment plant, ARA Werdhölzli, 8048 Zürich, Switzerland (22 January 2007)
- Pretreatment: The sludge was washed twice with tap water.

Duration of test (contact time):

28 d

Initial conc.:

20.7 - 20.9 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 ± 0.5 °C
- pH adjusted: Yes, the pH-value was checked at the beginning and at the end of the test and adjusted to pH 7.4 (± 0.2) with NaOH or HCL.
- Suspended solids concentration: 30 mg/L
- Continuous darkness: Yes, temperature-controlled dark room

TEST SYSTEM
- Culturing apparatus: 2500 mL closed glass bottle containing a total volume of test solution of 2000 mL
- Number of culture flasks/concentration: 2/concentration
- Method used to create aerobic conditions: Aerated with synthetic CO2-free air for a maximum test period of 28 days.
- Measuring equipment: Shimadzu 5050 TOC-Analyzer using the NPOC-mode for DOC-determination
- Details of trap for CO2: The air leaving the individual vessels was passed through gas-absorption bottles filled with NaOH.

SAMPLING
- Sampling frequency: on day 0, 1, 3, 8, 10, 14, 17, 21, 24 and 28
- Sampling method: Samples were centrifuged (15 min at 4500g) and acidified to pH<2. Prior to analysis the samples were sparged with CO2-free high purity air for 10 min to remove inorganic carbon.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

72

Sampling time:

28 d

Results with reference substance:

The reference substance was degraded to 90.6% at day 14 and to 87.9% at day 28.

The test substance is readily biodegradable under conditions tested. The biodegradation was > 60% after 28 days and the

10 -day-window was fulfilled, because the biodegradation reached 61% at the end of the 10 -day-window.

Table 1: Percentage biodegradation (mean of two replicates) of test and reference substance

Day	Test substance (% degradation)	Reference substance (% degradation)
0	0.0	0.0
1	1.9	11.2
3	4.7	48.8
8	39.1	75.1
10	48.5	78.2
14	61.7	90.6
17	67.7	90.1
21	74.7	88.1
24	72.8	88.4
28	72.0	87.9

 

Interpretation of results:

readily biodegradable

Description of key information

No relevant studies are available for decanoic acid, mixed esters with heptanoic acid, octanoic acid and trimethylolpropane. Ready biodegradability studies are available for closely related structural analogues (CAS 11138-60-6 and CAS 78-16-0).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Two studies, investigating the ready biodegradability of closely related structural analogues are available:

The first study was conducted in accordance with OECD Guideline 301B (CO2 Evolution Test). Domestic activated sludge (non adapted) was used as inoculum and a mean degradation of 72% after 28 days was observed. The 60% pass level at the 10-day-window was reached therefore the test substance can be classified as readily biodegradable according to OECD criteria.

The second study was also conducted in accordance with OECD Guideline 301B (CO2 Evolution Test). Domestic activated sludge (non adapted) was used as inoculum and a mean degradation of 85.3% after 28 days was observed. The 60% pass level at the 10-day-window was reached therefore the test substance can be classified as readily biodegradable according to OECD criteria.

A report justifying the read-across approach is included in IUCLID Chapter 13.