1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters

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:

1996-12-13 to 1997-01-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

Composition of medium: according to OECD guideline, sole deviation: pH 7.5 of solution 1

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

other: secondary effluent from a predominantly domestic sewage plant

Details on inoculum:

- Source of inoculum/activated sludge: public sewage treatment plant Plön, Germany
- Laboratory culture: no
- Storage conditions: keeping under aerobic conditions
- Storage length: not mentioned
- Preparation of inoculum for exposure: The inoculum was filtered through a coarse filter, the first 200 ml being discarded.
- Pretreatment: none
- Concentration of sludge: not mentioned
- Initial cell/biomass concentration: not measured
- Water filtered: not mentioned

Duration of test (contact time):

48 d

Initial conc.:

20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: according to OECD guideline, sole deviation: pH 7.5 of solution 1
- Additional substrate: none
- Solubilising agent (type and concentration if used): not used
- Test temperature: as close as possible to 20°C, no further measurements mentioned
- pH: 7.70 pH of medium, no further meassurements mentioned
- pH adjusted: no
- Aeration of dilution water: yes
- Suspended solids concentration: not determined
- Continuous darkness: yes, or only diffuse light
- Other: none

TEST SYSTEM
- Culturing apparatus: test bottles, no further details mentioned
- Number of culture flasks/concentration: 2 bottles, one concentration
- Method used to create aerobic conditions: not mentioned
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: titration with HCl 0.05 M using phenolphthalein as indicator
- Details of trap for CO2: 3 flasks containing 100 ml 0.0125 M barium hydroxide in a serial order
- Other: none


SAMPLING
- Sampling frequency: on days 2, 4, 7, 10, 14, 18, 24, 28, 31, 35, 40, 47, and 48
- Sampling method: On the day of measurement the barium hydroxid absorber was disconnencted closest to the flask and the solution was titrated. The remaining absorbers were moved one place closer to the flask and a new absorber was placed containing 100 ml fresh 0.0125 M barium hydroxid at the far end of the series.
- Sample storage before analysis: not mentioned
- Other: none


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (2 vessels with inoculum without test substance)
- Abiotic sterile control: not performed
- Toxicity control: not performed
- Other: none


STATISTICAL METHODS: no statistics performed

Reference substance:

acetic acid, sodium salt

Remarks:

51.33 mg/L final test medium (15 mg DOC/L)

Preliminary study:

not performed

Test performance:

Parallel groups of bottles were prepared for the determination of the test and reference chemical in simultaneous experimental series. The test was conducted in duplicate in a parallel series.

Parameter:

% degradation (CO2 evolution)

Value:

20.7

Sampling time:

28 d

Parameter:

% degradation (CO2 evolution)

Value:

ca. 71.4

Sampling time:

48 d

Details on results:

see below

Results with reference substance:

see below

Table: Degradation kinetic

sampling time [days]	degradation [%]
	test substance			reference substance
	vessel 1	vessel 2	mean
2	-0.1	0.1	0.0	16.3
4	-0.1	0.4	0.2	34.0
7	0.3	1.3	0.7	50.4
10	0.9	2.0	1.5	63.8
14	1.6	3.2	2.4	71.9
18	2.7	4.7	3.7	74.1
24	7.4	6.9	7.2	78.3
28	22.6	18.7	20.7	79.1
31	35.2	33.2	34.2	79.8
35	46.0	45.1	45.6	80.5
40	55.3	57.3	56.3	80.3
47	63.8	68.6	66.2	80.5
48	67.3	73.1	70.2	81.6
48#	68.7	74.1	71.4	81.6

# analysis of the second and third trap

Validity criteria fulfilled:

yes

Remarks:

Difference of extremes of replicate values was less than 20% and the percentage degradation of reference control reached the level for ready biodegradability by 14 days.

Interpretation of results:

inherently biodegradable

Conclusions:

Under the present test conditions, 71.4 % biodegradability was determined for 1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters at 48 days (20.7 % biodegradability at 28 days).

Executive summary:

The purpose of this test was the measurement of the biodegradability of 1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters in an aerobic, aqueous medium at a concentration of 10 - 20 mg DOC or TOC/L.

The study was conducted according to the OECD guideline 301B and the EEC guideline L383 A: C.4 -C.

A measured volume of inoculated mineral medium containing a known concentration of the test chemical (14.8 mg TOC/L) as the nominal sole source of organic carbon was aerated by the passage of carbon dioxide-free air at a controlled rate in the dark or in diffuse light. Degradation was followed over 48 days by determining he carbon dioxide produced, which was trapped in barium hydroxide and which was measured by titration of the residual hydroxide. The amount of carbon dioxide produced from the test chemical (corrected for that derived from the blank inoculum) was expressed as a percentage of ThCO2.

Under the present test conditions, 20.7 % biodegradability was determined for 1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters at 28 days (71.4 % biodegradability at 48 days).

Description of key information

71.4 % biodegradability was determined for 1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters at 48 days (20.7 % biodegradability at 28 days).

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Type of water:

freshwater