Reaction products of ((5E)-5-ethylidenebicyclo[2.2.1]hept-2-ene and (5Z)-5-ethylidenebicyclo[2.2.1]hept-2-ene) and 2-methyl-1,3-butadiene, epoxidized

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:

2015

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline screening study; non-GLP. Minor deviations from guideline not considered to impact the overall reliability of the study. No positive or toxicity controls utilised.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

yes

Remarks:

minor deviations not considered to have an impact on the reliability of the study.

Qualifier:

according to guideline

Guideline:

other: van Ginkel and Stroo (1992) Simple method to prolong the Closed Bottle test for the determination of the inherent biodegradability. Ecotox Environ Saf 24 319-327.

Deviations:

not applicable

Principles of method if other than guideline:

Minor deviations from the guidelines of the Closed Bottle test (OECD TG 301) were introduced: ammonium chloride was omitted from the medium to prevent oxygen consumption due to nitrification (omission does not result in nitrogen limitation as shown by the biodegradation of the reference compound); the study was extended using established inherent biodegradation determination literature methodology.

GLP compliance:

no

Remarks:

non-GLP; well documented study report. Conclusion: ‘not biodegradable’. The GLP study to OECD TG 301D would only be required to conclude if the test item were to be concluded as ‘readily biodegradable’ or ‘inherently biodegradable’.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): 1. Secondary activated sludge was obtained from the wastewater treatment plant Nieuwgraaf in Duiven, The Netherlands. This plant is an activated sludge plant treating predominantly domestic wastewater. 2. River water was sampled from the Rhine near Heveadorp, The Netherlands. This river water was aerated for 7 days before use and particles were removed by sedimentation. The river water spiked with mineral salts was used undiluted.
- Storage conditions: See pretreatment field.
- Storage length: < 1 week
- Preparation of inoculum for exposure:
- Pretreatment: The activated sludge was preconditioned to reduce the endogenous respiration rates. To this end, 400 mg Dry Weight (DW)/L of activated sludge was aerated for one week.
- Concentration of sludge: The sludge was diluted in the BOD bottles to 2 mg DW/L

Duration of test (contact time):

28 d

Initial conc.:

3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: The nutrient medium of the Closed Bottle test contained per liter of deionized water; 8.5 mg KH2PO4, 21.75 mg K2HPO4, 33.3 mg Na2HPO4•2H2O, 22.5 mg MgSO4•7H2O, 27.5 mg CaCl2, 0.25 mg FeCl3•6H2O. Ammonium chloride was omitted from the medium to prevent nitrification.
- Test temperature: Temperatures were within the prescribed temperature range of 22 to 24°C.
- pH: The pH of the media (activated sludge) was 7.3 and 8.0 (river water) at the start of the test. The pH of the medium at day 28 was 7.2 (activated sludge) and 7.9 (river water).
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers.
- Number of culture flasks/concentration: 3 bottles containing only inoculum, 3 bottles containing test substance with inoculum
- Measuring equipment: See details on analytical methods
- Test performed in closed vessels due to significant volatility of test substance: No.
- Test performed in open system: No.

SAMPLING
- Sampling frequency: Biodegradation was measured by following the course of the oxygen decrease in the bottles with a special funnel. This funnel fitted exactly in the BOD bottle. Subsequently, the oxygen electrode was inserted in the BOD bottle to measure the oxygen concentration. The medium dissipated by the electrode was collected in the funnel. After withdrawal of the oxygen electrode the medium collected flowed back into the BOD bottle, followed by removal of the funnel and closing of the BOD bottle.
- Sampling method: analyses of the dissolved oxygen concentration
- Sterility check if applicable: No.
- Sample storage before analysis: Not applicable.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Toxicity control: No.

Reference substance:

not required

Parameter:

% degradation (O2 consumption)

Value:

4

Sampling time:

28 d

Remarks on result:

other: Activated Sludge

Parameter:

% degradation (O2 consumption)

Value:

8

Sampling time:

82 d

Remarks on result:

other: Activated Sludge

Parameter:

% degradation (O2 consumption)

Value:

-1

Sampling time:

28 d

Remarks on result:

other: River water

Parameter:

% degradation (O2 consumption)

Value:

2

Sampling time:

84 d

Remarks on result:

other: River water

- Theoretical oxygen demand (ThOD): The calculated theoretical oxygen demand (ThOD) of the reaction mass of the test material is 2.9 mg/mg (reference reported in the present study report).

- Toxicity: Minor inhibition was detected prior to the onset of the biodegradation through suppression of the oxygen consumption in the presence of the test substance. Because of the 8% biodegradation found with activated sludge, toxic effects by the test substance are considered limited.

- Biodegradability: The test item started to degrade after 21 days in the test with activated sludge. A biodegradation percentage of 8 was found at day 42. The biodegradation did not increase after day 42. The test item can therefore not be classified as (readily) biodegradable.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Under the conditions of the study, the substance was biodegraded by 4 % at day 28 in the Closed Bottle test.

Executive summary:

The ready biodegradability was determined in the Closed Bottle test (OECD TG 301 D) performed according to slightly modified OECD, EU and ISO Test Guidelines but without parallel positive or toxicity controls in a limited screening study in an aerobic aqueous medium. The study was extended in accordance with established inherent biodegradation determination literature methodology. Minor inhibition was detected prior to the onset of the biodegradation through suppression of the oxygen consumption in the presence of the test substance. Because of the 8% biodegradation found with activated sludge (at 42 days), toxic effects by the test substance are considered limited. The test substance started to degrade after 21 days in the test with activated sludge. A biodegradation percentage of 8 was found at day 42. The biodegradation did not increase after day 42. The test substance can therefore not be classified as readily biodegradable.

Description of key information

Biodegradation: 4% (28-days) not readily biodegradable, OECD301D, 2015

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

The ready biodegradability was determined in the Closed Bottle test (OECD TG 301 D) performed according to slightly modified OECD, EU and ISO Test Guidelines but without parallel positive or toxicity controls in a limited screening study in an aerobic aqueous medium. The study was extended in accordance with established inherent biodegradation determination literature methodology. Minor inhibition was detected prior to the onset of the biodegradation through suppression of the oxygen consumption in the presence of the test substance. Because of the 8% biodegradation found with activated sludge (at 42 days), toxic effects by the test substance are considered limited. The test substance started to degrade after 21 days in the test with activated sludge. A biodegradation percentage of 8 was found at day 42. The biodegradation did not increase after day 42. The test substance can therefore not be classified as readily biodegradable.