2-ethylhexyl 2-([1,1'-biphenyl]-4-ylcarbonyl)benzoate

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 December 2020 to 04 May 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Adopted July 17, 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-ethylhexyl 2-([1,1'-biphenyl]-4-ylcarbonyl)benzoate

EC Number:

278-051-5

EC Name:

2-ethylhexyl 2-([1,1'-biphenyl]-4-ylcarbonyl)benzoate

Cas Number:

75005-95-7

Molecular formula:

C28H30O3

IUPAC Name:

2-ethylhexyl 2-{[1,1'-biphenyl]-4-carbonyl}benzoate

Test material form:

liquid

Details on test material:

Purity/Composition: 96.27%
Storage Conditions: At room temperature
Test Facility test item number: 210244/A
Test item handling: No specific handling conditions required
CAS number: 75005-95-7
EC Number: 278-051-5
Substance Name: 2-ethylhexyl 2-([1,1'-biphenyl]-4-ylcarbonyl)benzoate

Specific details on test material used for the study:

Physical Description: Colourless to pale yellow liquid (determined by Charles River Den Bosch)
Purity/Composition: 96.69%
Storage Conditions: At room temperature
Purity/Composition correction factor: No correction factor required
Test item handling: No specific handling conditions required
Chemical name : 2-Ethylhexyl 2-([1,1'-biphenyl]-4-ylcarbonyl)benzoate
CAS number: 75005-95-7
EC Number: 278-051-5
Molecular formula: C28H30O3
Molecular weight: 414.22

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands.
- Laboratory culture: not reported
- Method of cultivation: not reported
- Storage conditions: not reported
- Storage length: not reported
- Preparation of inoculum for exposure: Before the start of the test (Day -1) mineral components, Milli- RO water (ca. 80 % of final volume) and inoculum were added to each bottle. This mixture was aerated with synthetic air overnight to purge the system of CO2.
- Pretreatment: not reported
- Concentration of sludge: After treatment concentration of suspended solids (SS) was determined to be 3 g/L in concentrated sludge as used for the test
- Initial cell/biomass concentration: not reported
- Water filtered: yes
- Type and size of filter used, if any: 1 mm

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

30 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Stock solutions of mineral components: 8.50 g KH2PO4, 21.75 g K2HPO4, 67.20 g Na2HPO4.12H2O, 0.50 g NH4Cl, dissolved in Milli- RO water and made up to 1 liter, pH 7.4 ± 0.2, B) 22.50 g MgSO4.7H2O dissolved in Milli- RO water and made up to 1 liter, C) 36.40 g CaCl2.2H2O dissolved in Milli- RO water and made up to 1 liter, D) 0.25 g FeCl3.6H2O dissolved in Milli- RO water and made up to 1 liter. 1 L mineral medium contains: 10 mL of solution (A), 1 mL of solutions (B), (C), (D), and Milli-RO water.
- Additional substrate: Three CO2-absorbers (bottles filled with 100 mL 0.0125 M Ba(OH)2) were connected in series to the exit aeration line of each test bottle.
- Solubilising agent (type and concentration if used): not reported
- Test temperature: between 21 and 24 °C
- pH: test item bottle A: 7.6, test item bottle B: 7.6
- pH adjusted: not reported
- CEC (meq/100 g): not reported
- Aeration of dilution water: This mixture was aerated with synthetic air overnight to purge the system of CO2.
- Suspended solids concentration: 3 g/L
- Continuous darkness: not reported
- Other:

TEST SYSTEM
- Culturing apparatus: not reported
- Number of culture flasks/concentration: not reported
- Method used to create aerobic conditions: A mixture of oxygen (ca. 20 %) and nitrogen (ca. 80 %) was passed through a bottle, containing 0.5 - 1 liter 0.0125 M Ba(OH)2 solution to trap CO2 which might be present in small amounts. Synthetic air was passed through the scrubbing solutions at a rate of approximately 1-2 bubbles per second (ca. 30-100 mL/min).
- Method used to create anaerobic conditions: anaerobic conditions not used.
- Measuring equipment: not reported
- Test performed in closed vessels due to significant volatility of test substance: no
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: Three CO2-absorbers (bottles filled with 100 mL 0.0125 M Ba(OH)2) were connected in series to the exit aeration line of each test bottle.
- Other:

SAMPLING
- Sampling frequency: Titrations were made every second or third day during the first 10 days, and thereafter at least every fifth day until Day 28, for inoculum blank and test item.
- Sampling method: not reported
- Sterility check if applicable: not reported
- Sample storage before analysis: not reported
- Other:

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes
- Other:

STATISTICAL METHODS: not reported

Results and discussion

Preliminary study:

Not reported.

Test performance:

Not reported.

% Degradation

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 12 - <= 19

Sampling time:

28 d

Remarks on result:

other: The test item was not readily biodegradable under the conditions of the modified Sturm test.

Any other information on results incl. tables

Relative biodegradation values calculated from measurements performed during the test period revealed 19 % and 12 % biodegradation of C991 (based on ThCO2). Thus, the criterion for ready biodegradability (at least 60 % biodegradation within a 10-day window) was not met.

In the toxicity control, more than 25 % biodegradation occurred within 14 days (43 %, based on ThCO2). Therefore, the test item was considered not to inhibit microbial activity.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item was not readily biodegradable under the conditions of the modified Sturm test.

Executive summary:

The objective of the study was to evaluate the test item for its ready biodegradability in an aerobic aqueous medium with microbial activity introduced by inoculation with activated sludge.

The study met the validity criteria prescribed by the Study Plan and was considered to be valid.