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Environmental fate & pathways

Biodegradation in water: screening tests

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biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1996-12-13 to 1997-01-30
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Composition of medium: according to OECD guideline, sole deviation: pH 7.5 of solution 1
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters
EC Number:
EC Name:
1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters
Cas Number:
Molecular formula:
C33H51O6 to C39H66O6
tris(mixed decyl and octyl)benzene-1,2,4-tricarboxylate
Details on test material:
- Name of test material (as cited in study report): Linplast 810 TM
- Substance type: product
- Physical state: liquid
- Stability under test conditions: no data
- Storage condition of test material: at room temperature, protected from freeze, container stored in a well-ventilated room
- Other:
Test laboratory indentification: density = 0.970 g/cm³
Study sponsor identification: densitiy = 0.968 g/cm³ at 20°C

Study design

Oxygen conditions:
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 test substance concentration
Initial conc.:
20 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
- 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

- 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 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

- 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
Reference substance:
acetic acid, sodium salt
51.33 mg/L final test medium (15 mg DOC/L)

Results and discussion

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.
% Degradationopen allclose all
% degradation (CO2 evolution)
Sampling time:
28 d
% degradation (CO2 evolution)
ca. 71.4
Sampling time:
48 d
Details on results:
see below

BOD5 / COD results

Results with reference substance:
see below

Any other information on results incl. tables

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

Applicant's summary and conclusion

Validity criteria fulfilled:
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
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).