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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
yes
Remarks:
Laboratory temperature exceeding 22 +/-2oC for 19 h, max deviation 0.8oC
GLP compliance:
yes
Test material information:
Composition 1
Specific details on test material used for the study:
Test item: 4,4'-(1-phenylethane-1,1-diyl)bis(heptyloxybenzene)
Solubility and stability of the test substance in solvent/vehicle: Sparingly soluble in water
Purity: 99.56%
Purity test date: 01.02.2016
Test item storage: Room temperature
Stability under storage conditions: 21 March 2012 (expiry date)
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): Municipal sewage treatment plant, treating predominantly domestic sewage
- Storage conditions: continuously aerated
- Concentration of sludge: 3.7 g/L suspended solids
Duration of test (contact time):
<= 28 d
Initial conc.:
<= 12 mg/L
Based on:
ThCO2
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
other: sodium acetate
Key result
Parameter:
% degradation (CO2 evolution)
Value:
1
Sampling time:
28 d
Remarks on result:
other: individual vessel
Key result
Parameter:
% degradation (CO2 evolution)
Value:
4
Sampling time:
28 d
Remarks on result:
other: individual vessel

Day

Cumulative % biodegradation (corrected for blank)

Reference item

Toxicity control

Test item

2

4

3

0

5

30

17

0

7

45

25

0

9

57

30

1

14

68

34

1

19

-

-

1

23

-

-

1

27

-

-

4

29

-

-

5

Validity criteria fulfilled:
yes
Remarks:
Positve control biodegraded by >60% within 14 days
Interpretation of results:
not readily biodegradable
Conclusions:
The test item was measured to be <5% degraded within 28 days, and is therefore considered to be not readily biodegradable under the conditions of the test. The test substance had no inhibitory effect on the dedgradation, and the reference chemical, sodium acetate, was degraded by >60% within 14 days.
Executive summary:

A reliable study to determine the ready biodegradability of the test item following the interntationally acceptable test guideline OECD 301B is available for the test item.The test item was degraded by <5% after 28 days and was not readily biodegradable under the conditions of the test (CO2 evolution, modified Sturm test). The test validity criteria were met and there were no significant deviations noted.

Description of key information

A reliable study (Klimisch 1) to determine the ready biodegradability for the test substance, 4,4’-(1-phenylethane-1,1-diyl)bis(heptyloxybenzene), measured <5% degradation after 28 days, and should be classified as not readily biodegradable under the conditions of the test.

The test substance had no inhibitory effect on degradation and the reference chemical, sodium benzoate, was degraded by >60% after 14 days.

The test validity criteria were met and there were no significant deviations noted to affect the integrity of the study. This study is considered acceptable and satisfies the guideline requirements for a biodegradation in water: screening test.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information