2-(2-(4-methyl-3-cyclohexen-1-yl)propyl)cyclopentanone

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:

April 12, 2016 through July 29, 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

NECTARYL :
Commercial name : Nectaryl
Givaudan Code No. : 7446003
Empirical formula : C15H24O
Molecular weight : 220.35 g/mol
Lot No. : VE00434162
Purity : 95.2% (sum of the three peaks)
Expiration date : April 11, 2017

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland) was used.

The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.

The dry weight of suspended solids was determined by taking two 50 ml samples of the homogenised sludge, evaporating water on a steam bath, drying in an oven at 105 - 110°C for two hours and weighing the residue.

Dry weight of suspended solids: 6.23 g/l, diluted to 2.62 g/l

To obtain a concentration of 30 mg/l (dry weight) in 437 ml total volume, 5.00 ml of sludge (inoculum) was added to 432 ml of mineral medium.

Duration of test (contact time):

66 d

Initial conc.:

30.1 mg/L

Based on:

test mat.

Remarks:

Sample C1

Initial conc.:

30 mg/L

Based on:

test mat.

Remarks:

Sample C2

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Water :
The water used during this study is ultrapure water, containing less than 5 ppb total organic carbon, produced by using a Millipore Direct-Q 3 UV purification system.

Preparation of the Test Flasks :
Test substance samples (13.10 mg, corresponding to 30.0 mg/l in 437 ml of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop. For reference substance samples 43.70 mg (corresponding to 100.0 mg/l in 437 ml of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop.

Flasks are filled with 432 ml of mineral medium. Samples of test or reference substance are added. Then 5.00 ml of suspended sludge diluted to a concentration of 2.62 g/l dry matter is added. Except when the test substance has an acid or alkaline character, the pH of each flask is not measured but assumed to be the same as the mineral medium, in order not to remove any floating undissolved test substance from the test medium by dipping a glass electrode in it. Neutral test substances, even sodium benzoate, were shown not to affect the pH of the medium by more than 0.1 pH unit. Two sodium hydroxide pellets are placed in the quivers on top of the bottle, and the flasks are closed tightly with the measuring heads. The flasks are allowed to equilibrate to the test temperature. The measurement is started by programming the measuring unit of the Oxitop test flasks, and the test flasks are placed in the temperature controlled cupboard of the Oxitop system. After temperature equilibration, the controller of the instrument starts the data acquisition (time zero of the experiment).

Everyday the oxygen consumption of each flask is recorded and correct temperature and stirring are checked.

At the end of the test period (in this case, the study was extended to 66 days, since this study on Nectaryl was part of a series of other incubations performed in parallel of other test items), the pH of each flask is measured again.

Reference substance:

benzoic acid, sodium salt

Remarks:

Sodium benzoate (Fluka, Buchs, Switzerland, Art. No. 71300), purity : min. 99.0%. Test concentration was 100 mg/L.

Key result

Parameter:

% degradation (O2 consumption)

Value:

66

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

76

Sampling time:

42 d

Parameter:

% degradation (O2 consumption)

Value:

81

Sampling time:

66 d

Details on results:

The Ready Biodegradability of Nectaryl was determined by the Manometric Respirometry Test.

Nectaryl did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

Nectaryl undergoes 66% biodegradation after 28 days in the test conditions. The 10-day window criterion is not fulfilled (20% biodegradation on day 11 and 52% on day 21). The 10-day time window criterion was developed on the assumption that a test substance is degraded according to a “standard” growth curve in ready biodegradability tests. The OECD Guidelines for Testing of Chemicals, Section 3. Part 1: Principles and strategies related to the testing of degradation of organic chemicals (adopted 23 March 2006), states that if a substance consists of “constituents with different chain-lengths, degree and/or site of branching or stereo-isomers, even in their most purified commercial forms” and “it is anticipated that a sequential biodegradation of the individual structures is taking place, then the 10-day window should not be applied to interpret the results of the test.” The 10-day time-window should therefore not be applied as a pass / fail criterion for Nectaryl, which is a mixture of four stereoisomers. Thus, Nectaryl should be regarded as readily biodegradable according to this test based on the biodegradation percentage of 66% at day 28.

Results with reference substance:

Degradation of sodium benzoate exceeded 40% after 7 days (measured = 69% degradation) and 65% after 14 days (measured = 79% degradation): the activity of the inoculum was thus verified (validity criterion).

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Nectaryl did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

Nectaryl undergoes 66% biodegradation after 28 days in the test conditions. The 10-day window criterion is not fulfilled (20% biodegradation on day 11 and 52% on day 21). The 10-day time window criterion was developed on the assumption that a test substance is degraded according to a “standard” growth curve in ready biodegradability tests. The OECD Guidelines for Testing of Chemicals, Section 3. Part 1: Principles and strategies related to the testing of degradation of organic chemicals (adopted 23 March 2006), states that if a substance consists of “constituents with different chain-lengths, degree and/or site of branching or stereo-isomers, even in their most purified commercial forms” and “it is anticipated that a sequential biodegradation of the individual structures is taking place, then the 10-day window should not be applied to interpret the results of the test.” The 10-day time-window should therefore not be applied as a pass / fail criterion for Nectaryl, which is a mixture of four stereoisomers. Thus, Nectaryl should be regarded as readily biodegradable according to this test based on the biodegradation percentage of 66% at day 28.

Executive summary:

Nectaryl did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be

non-toxic to the inoculum at the test concentration.

 

Nectaryl undergoes 66% biodegradation after 28 days in the test conditions.The 10-day window criterion is not fulfilled (20% biodegradation on day 11 and 52% on day 21).The 10-day time window criterion was developed on the assumption that a test substance is degraded according to a “standard” growth curve in ready biodegradability tests. The OECD Guidelines for Testing of Chemicals, Section 3. Part 1: Principles and strategies related to the testing of degradation of organic chemicals (adopted 23 March 2006), states that if a substance consists of “constituents with different chain-lengths, degree and/or site of branching or stereo-isomers, even in their most purified commercial forms” and “it is anticipated that a sequential biodegradation of the individual structures is taking place, then the 10-day window should not be applied to interpret the results of the test.” The 10-day time-window should therefore not be applied as a pass / fail criterion for Nectaryl, which is a mixture of four stereoisomers. Thus,Nectarylshould be regarded as readily biodegradable according to this test based on the biodegradation percentage of 66% at day 28.

Description of key information

In an OECD 301F ready biodegradability study, Nectaryl did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

Nectaryl undergoes 66% biodegradation after 28 days in the test conditions. The 10-day window criterion is not fulfilled (20% biodegradation on day 11 and 52% on day 21). The 10-day time window criterion was developed on the assumption that a test substance is degraded according to a “standard” growth curve in ready biodegradability tests. The OECD Guidelines for Testing of Chemicals, Section 3. Part 1: Principles and strategies related to the testing of degradation of organic chemicals (adopted 23 March 2006), states that if a substance consists of “constituents with different chain-lengths, degree and/or site of branching or stereo-isomers, even in their most purified commercial forms” and “it is anticipated that a sequential biodegradation of the individual structures is taking place, then the 10-day window should not be applied to interpret the results of the test.” The 10-day time-window should therefore not be applied as a pass / fail criterion for Nectaryl, which is a mixture of four stereoisomers. Thus, Nectaryl should be regarded as readily biodegradable according to this test based on the biodegradation percentage of 66% at day 28.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

NECTARYL is READILY BIODEGRADABLE.