Fatty acids, C8-10, mixed esters with neopentyl glycol and trimethylolpropane

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 Oct - 14 Nov 2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

non-GLP, no purity

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 wastewater treatment plant, ARA Werdhölzli, Zürich, Switzerland (11 Oct 2006)
- Pretreatment: Prior to the test the sludge was washed twice tap water.

Duration of test (contact time):

28 d

Initial conc.:

10 - 20 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 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, 7, 10, 14, 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: yes, 2 vessels
- Abiotic sterile control: no
- Toxicity control: no
- Other: yes, procedure control, 1 vessels

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

79.4

Sampling time:

28 d

Remarks on result:

other: Mean of two replicates

Results with reference substance:

The reference substance reached 94% biodegradation after 14 days.

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 65% at the end of the 10 -day-window.

Percentage biodegradation of test substance (mean oft two replicates) and reference substance

Day	Test substance (% degradation)			Reference substance (% degradation)
	Test unit no. 1	Test unit no. 2	Mean degradation
0	0.0	0.0	0.0	0.0
1	0.0	-0.7	-0.4	3.3
3	9.3	4.7	7.0	46.3
7	46.7	33.7	40.2	78.8
10	53.7	56.2	54.9	93.9
14	64.9	68.3	66.6	93.5
21	69.1	77.4	73.2	98.3
24	74.1	79.1	76.6	96.4
28	75.8	83.0	79.4	98.2

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable: 79.4% (CO2 evolution) after 28 d (OECD 301B)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

One experimental study is available investigating the ready biodegradability of Fatty acids, C8-10 (even numbered), diesters with neopentyl glycol and di- and triesters with trimethylolpropane (Oleon, 2006). The study was conducted according to OECD 301B using non-adapted activated sludge from a municipal sewage treatment plant. After 28 d a biodegradation of 79.4% (O2 consumption) was recorded. The 10-day window was met and the substance is considered to be readily biodegradable according to the OECD criteria.