Cyclopropanecarboxylic acid, 2-[1-(3,3-dimethylcyclohexyl)ethoxy]-2-methylpropyl ester

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11-06-2009 to 17-09-2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP. All relevant validity criteria were met.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Including substance specific analysis and extended from 28 to to 61 days

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected: March 2008 ; signature: June 2008

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): A mixed population of activated sewage sludge micro-organisms (Test System) was obtained from the sewage treatment plant at Bois-de-Bay (Satigny, Switzerland)), which treats predominantly domestic sewage.
- Storage conditions: See pretreatment field.
- Storage length: < 1 week
- Preparation of inoculum for exposure: 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.
- Pretreatment: The sample of activated sewage sludge was maintained on continuous aeration upon receipt. 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. Determination of dry weight is made to inoculate final solution with 30mg/L dry weight activated sludge.
- Concentration of sludge: The sludge was diluted in the BOD bottles to 30 mg DW/L. Dry weight of suspended solids: 1.53 g/L. To obtain a concentration of 30 mg/L (dry weight) in 103 mL of test medium, 2.00 mL of sludge is needed (inoculum). To obtain a concentration of 30 mg/L (dry weight) in 255 mL of test medium, 5.00 mL of sludge is needed (inoculum).

Duration of test (contact time):

>= 28 - <= 61 d

Initial conc.:

20 mg/L

Based on:

test mat.

Remarks:

nominal

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: See table 1. 10 mL of Solution A [KH2PO4: 8.50 g/L; K2HPO4: 21.75g/L; Na2HPO4,2H2O: 33.40 g/L; NH4Cl: 0.50 g/L]; mineral medium: prepared by mixing 50 mL of solution A and 2000 mL deionised water, adding 5 mL of each of the solutions B, C and D and making up to 5 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide.
- Solubilising agent (type and concentration if used): None.
- Test temperature: 22 ±1 °C
- pH: See table 1.
- pH adjusted: No. (final pH was in the range of 7.4 to 7.53 for test item vessels)
- Aeration of dilution water: Not reported
- Suspended solids concentration: 30 mg/L dry weight
- Continuous darkness: No. The test was conducted in diffuse light.

TEST SYSTEM
- Culturing apparatus: 200mL glass flasks with continuous stirring (fill volume ca. 200 mL)
- Number of culture flasks/concentration: In duplicate (test item); In duplicate (Inoculum blank, Abiotic Sterile Control and toxicity control)
- Method used to create aerobic conditions: Sealed flasks wth sensor head/CO2 trap.
- Measuring equipment: The respirometer used during this study is an Oxitop Control System (WTW oxitopC). Evolved carbon dioxide is absorbed by the CO2 trap.

SAMPLING
- Sampling frequency: Daily.
- Sampling method: The respirometer used during this study is an Oxitop Control System.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes. See table 1.
- Abiotic sterile control: Yes.
- Toxicity control: Yes.
- Other: Positive reference control (Sodium Benzoate).

Reference substance:

benzoic acid, sodium salt

Remarks:

99.0 mg/L

Test performance:

1. The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test item at end of 10-day window and/or on day 28. Therefore, the test is considered valid.
2. The BOD of the inoculated blank control was 21.5 mgO2/L and 24.2 mgO2/L and < 60 mgO2/L after 28 days
3. The pH at day 28 was in the range of 6.0 to 8.5
4. The toxicity test exceeded 60% degradation at 14 days and 85% degradation after 28 days thereby confirming that the test material was not toxic to the sewage treatment microorganisms used in the study.
5. Sodium Benzoate exceeded 40% degradation at 7 days and 65% degradation after 14 days thereby confirming the suitability of the inoculum and test conditions.

Parameter:

% degradation (O2 consumption)

Value:

13

Sampling time:

28 d

Remarks on result:

other: 10-day window not met

Parameter:

% degradation (O2 consumption)

Value:

29

Sampling time:

60 d

Remarks on result:

other:

Details on results:

The 10-day window criteria was not met in all replicates.

Results with reference substance:

Sodium Benzoate exceeded 40% degradation at 7 days and 65% degradation after 14 days thereby confirming the suitability of the inoculum and test conditions.

Accompanying quantitative analysis for the test substance evidences rapid disappearance of the test item. This was evidenced as rapid primary biodegradation (DT50 parent < 24 hours and DT90 < 5 days). The The corresponding alcohol was identified as a primary metabolite by comparison to standard reference material. The alcohol was shown to further degrade to 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid by comparison to standard reference material. No test item or reference item other than 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid was detected at the end of the test period.

 

Table 2.0 – Results of specific analysis

Time / day	% initial concentration of test item				Mean % initial concentration of test item	Replicates (n=)
0	95.4	95.6			95.5	2
1	32.2	32.3			32.3	2
2	19.6	22.9			21.3	2
5	0.2	1.0			0.6	2
7	6.1	0.0			3.1	2
9	1.1	1.7			1.4	2
16	0.0	0.0			0.0	2
30	0.0	0.0			0.0	2
61.6	0.0	0.0	0.0	0.0	0.0	4

Since recoveries of the test item primary and secondary metabolites were < 70% the corresponding results are only semi-quantitative and qualitative interpretation. This is why metabolite formation is not presented above.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The mean biodegradation in duplicate was 13 % at day 28. The 10-day window criteria was not met. 29 % degradation was observed by day 60. Substance specific analysis indicated evidence of rapid disappearance of the test item. This was evidenced as rapid primary biodegradation (DT50 parent < 24 hours and DT90 < 5 days). The corresponding alcohol: 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropan-1-ol isomers were identified as a primary metabolite(s) by comparison to standard reference material. The alcohol was shown to further degrade to 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid by comparison to standard reference material. No test item or reference item other than 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid was detected at the end of the test period.

Executive summary:

The ready biodegradability test was carried out according to OECD TG 301F guideline under GLP. The test item, at a concentration of 20.0 mg/L A mixed population of activated sewage sludge micro-organisms (Test System) was obtained from the sewage treatment plant at Bois-de-Bay (Satigny, Switzerland)), which treats predominantly domestic sewage with culture medium in sealed culture vessels in diffused light at 22°C ± 1°C for 28 days. This was later extended to 61 days with substance specific analysis. The sludge was diluted in the BOD bottles to 30 mg DW/L. The degradation of the test item was assessed by the measurement of daily oxygen consumption on days 0 and 28 and latterly to 61 days using an Oxitop control system. Control solutions with inoculum and the reference substance, sodium benzoate, together with a toxicity control were used for validation purposes. In the test inoculum blank the oxygen uptake was < 30 mg O2/L. The pH value at the end of the test period 28 days did not exceed 7.6 in the test item systems and 8.02 in the reference item system. The test system met the validation criteria of the guideline. The toxicity test exceeded 60% degradation at 14 days and 85% degradation after 28 days thereby confirming that the test material was not toxic to the sewage treatment microorganisms used in the study. Sodium Benzoate exceeded 40% degradation at 7 days and 65% degradation after 14 days thereby confirming the suitability of the inoculum and test conditions. The mean biodegradation in duplicate was 13 % at day 28. The 10-day window criteria was not met. 29 % degradation was observed by day 60. Substance specific analysis indicated evidence of rapid disappearance of the test item. This was evidenced as rapid primary biodegradation (DT50 parent < 24 hours and DT90 < 5 days). The corresponding alcohol was identified as a primary metabolite by comparison to standard reference material. The alcohol was shown to further degrade to 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid by comparison to standard reference material. Under the conditions of the study, test item is not considered as readily biodegradable. The substance is rapidly degraded to primary and then secondary metabolite (by oxidation) which were identified within the study. No test item or reference item other than 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid was detected at the end of the test period.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Remarks:

biodegradation metabolite of registered substance

Adequacy of study:

supporting study

Study period:

11-06-2009 to 17-09-2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP. All relevant validity criteria were met.

Remarks:

GLP; well documented study report following a method according to, equivalent or similar to guideline with acceptable deviations which is supplemented by additional information according to the regulatory conclusion the substance is (bio)degraded.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected: March 2008 ; signature: June 2008

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): A mixed population of activated sewage sludge micro-organisms (Test System) was obtained from the sewage treatment plant at Bois-de-Bay (Satigny, Switzerland)), which treats predominantly domestic sewage.
- Storage conditions: See pretreatment field.
- Storage length: < 1 week
- Preparation of inoculum for exposure: 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.
- Pretreatment: The sample of activated sewage sludge was maintained on continuous aeration upon receipt. 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. Determination of dry weight is made to inoculate final solution with 30 mg/L dry weight activated sludge.
- Concentration of sludge: The sludge was diluted in the BOD bottles to 30 mg DW/L. Dry weight of suspended solids: 1.53 g/L. To obtain a concentration of 30 mg/L (dry weight) in 103 mL of test medium, 2.00 mL of sludge is needed (inoculum). To obtain a concentration of 30 mg/L (dry weight) in 255 mL of test medium, 5.00 mL of sludge is needed (inoculum).

Duration of test (contact time):

28 d

Initial conc.:

30 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: See table 1. 10 mL of Solution A [KH2PO4: 8.50 g/L; K2HPO4: 21.75g/L; Na2HPO4,2H2O: 33.40 g/L; NH4Cl: 0.50 g/L]; mineral medium: prepared by mixing 50 mL of solution A and 2000 mL deionised water, adding 5 mL of each of the solutions B, C and D and making up to 5 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide.
- Solubilising agent (type and concentration if used): None.
- Test temperature: 22 ±1 °C
- pH: See table 1.
- pH adjusted: No. (final pH was in the range of 7.39 to 7.41 for test item vessels)
- Aeration of dilution water: Not reported
- Suspended solids concentration: 30 mg/L dry weight
- Continuous darkness: No. The test was conducted in diffuse light.

TEST SYSTEM
- Culturing apparatus: 200mL glass flasks with continuous stirring (fill volume ca. 200 mL)
- Number of culture flasks/concentration: In duplicate (test item); In duplicate (Inoculum blank, Abiotic Sterile Control and toxicity control)
- Method used to create aerobic conditions: Sealed flasks wth sensor head/CO2 trap.
- Measuring equipment: The respirometer used during this study is an Oxitop Control System (WTW oxitopC). Evolved carbon dioxide is absorbed by the CO2 trap.

SAMPLING
- Sampling frequency: Daily.
- Sampling method: The respirometer used during this study is an Oxitop Control System.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes. See table 1.
- Abiotic sterile control: Yes.
- Toxicity control: Yes.
- Other: Positive reference control (Sodium Benzoate).

Reference substance:

benzoic acid, sodium salt

Remarks:

99.0 mg/L

Test performance:

1. The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test item at end of 10-day window and/or on day 28. Therefore, the test is considered valid.
2. The BOD of the inoculated blank control was 40.4 mgO2/L and 39.0 mgO2/L and < 60 mgO2/L after 28 days
3. The pH at day 28 was in the range of 6.0 to 8.5
4. The toxicity test exceeded 60% degradation at 14 days and 99% degradation after 28 days thereby confirming that the test material was not toxic to the sewage treatment microorganisms used in the study.
5. Sodium Benzoate exceeded 40% degradation at 7 days and 65% degradation after 14 days thereby confirming the suitability of the inoculum and test conditions.

Parameter:

% degradation (O2 consumption)

Value:

2

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

6

Sampling time:

66 d

Details on results:

The 10-day window criteria was not met in all replicates.

Results with reference substance:

Sodium Benzoate exceeded 40% degradation at 7 days and 65% degradation after 14 days thereby confirming the suitability of the inoculum and test conditions.

Accompanying analysis for the test substance evidences significant disappearance of the test item. This was evidenced as primary biodegradation. The corresponding carboxylic acid was identified as a primary metabolite by comparison to standard reference material. The metabolite was identified as 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid. Analysis of the test flasks at the end of the experiment showed that the test item had disappeared from the test medium (no test item was recovered from the test flasks ). Disappearance of the test substance can be regarded as evidence for a primary biodegradation

 

Since recoveries of the test item primary metabolites were < 70% the corresponding results are only semi-quantitative and qualitative interpretation. This is why metabolite formation is not presented above. This is evidence however, of metabolite identification and mechanism.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Remarks:

primary biodegradation metabolite of registered substance

Conclusions:

The mean biodegradation in duplicate was 2 % at day 28. The 10-day window criteria was not met. 6 % degradation was observed by day 66. Substance specific analysis indicated evidence of disappearance of the test item at the end of the test. The corresponding carboxylic acid was identified as a primary metabolite by comparison to standard reference material. The metabolite was identified as 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid. The substance is degraded to primary metabolite which was identified within the study.

Executive summary:

The ready biodegradability test was carried out according to OECD TG 301F guideline under GLP. The test item, at a concentration of 30.0 mg/L A mixed population of activated sewage sludge micro-organisms (Test System) was obtained from the sewage treatment plant at Bois-de-Bay (Satigny, Switzerland)), which treats predominantly domestic sewage with culture medium in sealed culture vessels in diffused light at 22°C ± 1°C for 28 days. This was later extended to 66 days with substance specific analysis. The sludge was diluted in the BOD bottles to 30 mg DW/L. The degradation of the test item was assessed by the measurement of daily oxygen consumption on days 0 and 28 and latterly to 66 days using an Oxitop control system. Control solutions with inoculum and the reference substance, sodium benzoate, together with a toxicity control were used for validation purposes. In the test inoculum blank the oxygen uptake was < 60 mg O2/L. The pH value at the end of the test period 28 days did not exceed 7.5 in the test item systems and 8.1 in the reference item system. The test system met the validation criteria of the guideline. The toxicity test exceeded 60% degradation at 14 days and 99% degradation after 28 days thereby confirming that the test material was not toxic to the sewage treatment microorganisms used in the study. Sodium Benzoate exceeded 40% degradation at 7 days and 65% degradation after 14 days thereby confirming the suitability of the inoculum and test conditions. The mean biodegradation in duplicate was 2 % at day 28. The 10-day window criteria was not met. 6% degradation was observed by day 66. Substance specific analysis indicated evidence of disappearance of the test item at the end of the test. The corresponding carboxylic acid was identified as a primary metabolite by comparison to standard reference material. The metabolite was identified as 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid. Under the conditions of the study, test item is not considered as readily biodegradable. The substance is degraded to primary metabolite which was identified within the study.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

12-09-2011 to 13-10-2011

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

non-GLP; well documented study report following a method according to, equivalent or similar to guideline with acceptable deviations which is supplemented by additional information according to the regulatory conclusion the substance is (bio)degraded.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

extended from 28 to to 42 days

Deviations:

no

Principles of method if other than guideline:

In accordance with REACH Regulation (EC) 1907/2006: Annex XI: section 1.1.2 adequate and reliable (with restrictions) study information has been provided (not in accordance with GLP) but which can be considered equivalent to the relevant test method and/or that will be supplemented with additional information in weight of evidence in accordance with : REACH Regulation (EC) 1907/2006: Annex XI: section 1.2. A well documented study report following a method according to, equivalent or similar to guideline with acceptable deviations which is supplemented by additional information according to the regulatory conclusion the substance is (bio)degraded.

GLP compliance:

no

Remarks:

see "Principles of method if other than guideline" field for explanation

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The water used during this study was water from the Rhone river, sampled upstream of the sponsor site in Vernier (Switzerland). The water was sieved and filtered through paper filter in order to remove particles. The measured pH of the water was 8.0.
- Storage conditions: See below.
- Storage length: < 1 week
- Preparation of inoculum for exposure: All flasks are filled with 250 mL of river water. Samples of test substance are 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 in the river water, in order not to remove any floating undissolved test substance from the test medium by dipping a glass electrode in it. 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 cooled to about 18 - 20 °C. 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 to 22 °C, the controller of the instrument starts the data acquisition
(time zero of the experiment).
- Pretreatment: Not applicable.
- Concentration of sludge: Not applicable.

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Test substance samples (5.00 mg, corresponding to 20 mg/L in 250 mL) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop. All flasks are filled with 250 ml of river water. Samples of test item are added.
- Solubilising agent (type and concentration if used): None.
- Test temperature: 22 ±1 °C
- pH: See below. Initial pH was 8.0 for test item vessels and control vessels.
- pH adjusted: No. (final pH was in the range of 8.98 for test item vessels and 8.97 to 9.02 blank control vessels)
- Aeration of dilution water: Not reported
- Suspended solids concentration: Not applicable.
- Continuous darkness: No. The test was conducted in diffuse light.

TEST SYSTEM
- Culturing apparatus: 250mL glass flasks with continuous stirring (fill volume ca. 250 mL)
- Number of culture flasks/concentration: In duplicate (test item); In duplicate (Inoculum blank)
- Method used to create aerobic conditions: Sealed flasks wth sensor head/CO2 trap.
- Measuring equipment: The respirometer used during this study is an Oxitop Control System (WTW oxitopC). Evolved carbon dioxide is absorbed by the CO2 trap.

SAMPLING
- Sampling frequency: Daily.
- Sampling method: The respirometer used during this study is an Oxitop Control System.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes.
- Abiotic sterile control: No
- Toxicity control: No.
- Other: Positive reference control (Sodium Benzoate) in a parallel study (documented in the full study report) indicated that the inoculum was active.

Reference substance:

benzoic acid, sodium salt

Test performance:

1. The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test item at end of 10-day window and on day 28. Therefore, the test is considered valid.
2. The BOD of the inoculated blank control was 11.2 mgO2/L and 8.4 mgO2/L and < 60 mgO2/L after 28 days

Note: The pH at day 28 was not in the range of 6.0 to 8.5 (actual 8.97 for test item vessels and 8.98 to 9.02 in blank controls).

Parameter:

% degradation (O2 consumption)

Value:

20

Sampling time:

28 d

Remarks on result:

other: 10-day window not met

Parameter:

% degradation (O2 consumption)

Value:

24

Sampling time:

42 d

Remarks on result:

other:

Results with reference substance:

Positive reference control (Sodium Benzoate) in a parallel study (documented in the full study report) indicated that the inoculum was active.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The mean biodegradation in duplicate was 28 % at day 28. The 10-day window criteria was not met. The test item undergoes 24% degradation at day 42 under the test conditions.

Executive summary:

The ready biodegradability test was carried out according to OECD TG 301F guideline. The test item, at a concentration of 20 mg/L was exposed to micro-organisms originating from natural river water in sealed culture vessels in diffused light at 22°C ± 1°C for 28 days but later extended to 42 days. The water used during this study was water from the Rhone river, sampled upstream of the sponsor site in Vernier (Switzerland). The water was sieved and filtered through paper filter in order to remove particles. The measured pH of the water was 8.0. The degradation of the test item was assessed by the measurement of daily oxygen consumption on days 0 and 28 and until the end of the test on day 42 using an Oxitop control system. Control solutions with inoculum were used for comparative validation purposes. A separate reference item test using sodium benzoate indicated activity of the inoculum. In the test inoculum blank the oxygen uptake was < 30 mg O2/L. The pH value at the end of the test period 28 days did exceeded 8.5 in the test item replicates and the inoculum blanks. The mean biodegradation in duplicate was 20 % at day 28. The 10-day window criteria was not met. The test item undergoes 24% degradation at day 42. Under the conditions of the study, test item is not considered as readily biodegradable.

Description of key information

1. Biodegradation: not readily biodegradable, mean biodegradation 13 % (28-days; 10-day window not met), at 60 days 29% biodegradation, activated sludge, OECD TG 301F, 2010a

Substance specific analysis indicated evidence of rapid disappearance of the test item. This was evidenced as rapid primary biodegradation (DT50 parent < 24 hours and DT90 < 5 days). The corresponding alcohol was identified as a primary metabolite by comparison to standard reference material. The alcohol was shown to further degrade to 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid by comparison to standard reference material. Under the conditions of the study, test item is not considered as readily biodegradable. The substance is rapidly degraded to primary and then secondary metabolite (by oxidation) which were identified within the study.

 

2. Biodegradation: not readily biodegradable, mean biodegradation 20 % (28-days; 10-day window not met), river water, OECD TG 301F, 2010b

The level of % BOD seen in the two studies performed on the parent substance (i.e. 29% 2010a; 20% 2010b) is likely attributable to the mineralisation of cyclopropane carboxylic acid (i.e. the other expected primary metabolite from ester cleavage of parent substance).

3. Supporting information on (bio)degradation metabolite : 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropan-1-ol (biodegradation metabolite of registered substance) : Biodegradation: not readily biodegradable, mean biodegradation 2 % (28-days; 10-day window not met), at 66 days 6% biodegradation, activated sludge, OECD TG 301F, 2010c

Substance specific analysis indicated evidence of disappearance of the test item at the end of the test. The corresponding carboxylic acid was identified as a primary metabolite by comparison to standard reference material. The metabolite was identified as 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid. The substance is degraded to primary metabolite which was identified within the study.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

Key study : OECD TG 301F, 2010a : The ready biodegradability test was carried out according to OECD TG 301F guideline under GLP. The test item, at a concentration of 20.0 mg/L A mixed population of activated sewage sludge micro-organisms (Test System) was obtained from the sewage treatment plant at Bois-de-Bay (Satigny, Switzerland)), which treats predominantly domestic sewage with culture medium in sealed culture vessels in diffused light at 22°C ± 1°C for 28 days. This was later extended to 61 days with substance specific analysis. The sludge was diluted in the BOD bottles to 30 mg DW/L. The degradation of the test item was assessed by the measurement of daily oxygen consumption on days 0 and 28 and latterly to 61 days using an Oxitop control system. Control solutions with inoculum and the reference substance, sodium benzoate, together with a toxicity control were used for validation purposes. In the test inoculum blank the oxygen uptake was < 30 mg O2/L. The pH value at the end of the test period 28 days did not exceed 7.6 in the test item systems and 8.02 in the reference item system. The test system met the validation criteria of the guideline. The toxicity test exceeded 60% degradation at 14 days and 85% degradation after 28 days thereby confirming that the test material was not toxic to the sewage treatment microorganisms used in the study. Sodium Benzoate exceeded 40% degradation at 7 days and 65% degradation after 14 days thereby confirming the suitability of the inoculum and test conditions. The mean biodegradation in duplicate was 13 % at day 28. The 10-day window criteria was not met. 29 % degradation was observed by day 60. Substance specific analysis indicated evidence of rapid disappearance of the test item. This was evidenced as rapid primary biodegradation (DT50 parent < 24 hours and DT90 < 5 days). The corresponding alcohol was identified as a primary metabolite by comparison to standard reference material. The alcohol was shown to further degrade to 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid by comparison to standard reference material. Under the conditions of the study, test item is not considered as readily biodegradable. The substance is rapidly degraded to primary and then secondary metabolite (by oxidation) which were identified within the study. No test item or reference item other than 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid was detected at the end of the test period.

 

Supporting study : OECD TG 301F, 2010b : The ready biodegradability test was carried out according to OECD TG 301F guideline. The test item, at a concentration of 20 mg/L was exposed to micro-organisms originating from natural river water in sealed culture vessels in diffused light at 22°C ± 1°C for 28 days but later extended to 42 days. The water used during this study was water from the Rhone river, sampled upstream of the sponsor site in Vernier (Switzerland). The water was sieved and filtered through paper filter in order to remove particles. The measured pH of the water was 8.0. The degradation of the test item was assessed by the measurement of daily oxygen consumption on days 0 and 28 and until the end of the test on day 42 using an Oxitop control system. Control solutions with inoculum were used for comparative validation purposes. A separate reference item test using sodium benzoate indicated activity of the inoculum. In the test inoculum blank the oxygen uptake was < 30 mg O2/L. The pH value at the end of the test period 28 days did exceeded 8.5 in the test item replicates and the inoculum blanks. The mean biodegradation in duplicate was 20 % at day 28. The 10-day window criteria was not met. The test item undergoes 24% degradation at day 42. Under the conditions of the study, test item is not considered as readily biodegradable.

 

Supporting information on (bio)degradation metabolite : (2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropan-1-ol), OECD TG 301F, 2010c : The ready biodegradability test was carried out according to OECD TG 301F guideline under GLP. The test item, at a concentration of 30.0 mg/L A mixed population of activated sewage sludge micro-organisms (Test System) was obtained from the sewage treatment plant at Bois-de-Bay (Satigny, Switzerland)), which treats predominantly domestic sewage with culture medium in sealed culture vessels in diffused light at 22°C ± 1°C for 28 days. This was later extended to 66 days with substance specific analysis. The sludge was diluted in the BOD bottles to 30 mg DW/L. The degradation of the test item was assessed by the measurement of daily oxygen consumption on days 0 and 28 and latterly to 66 days using an Oxitop control system. Control solutions with inoculum and the reference substance, sodium benzoate, together with a toxicity control were used for validation purposes. In the test inoculum blank the oxygen uptake was < 60 mg O2/L. The pH value at the end of the test period 28 days did not exceed 7.5 in the test item systems and 8.1 in the reference item system. The test system met the validation criteria of the guideline. The toxicity test exceeded 60% degradation at 14 days and 99% degradation after 28 days thereby confirming that the test material was not toxic to the sewage treatment microorganisms used in the study. Sodium Benzoate exceeded 40% degradation at 7 days and 65% degradation after 14 days thereby confirming the suitability of the inoculum and test conditions. The mean biodegradation in duplicate was 2 % at day 28. The 10-day window criteria was not met. 6% degradation was observed by day 66. Substance specific analysis indicated evidence of disappearance of the test item at the end of the test. The corresponding carboxylic acid was identified as a primary metabolite by comparison to standard reference material. The metabolite was identified as 2-(1-(3,3-dimethylcyclohexyl)ethoxy)-2-methylpropanoic acid. Under the conditions of the study, test item is not considered as readily biodegradable. The substance is degraded to primary metabolite which was identified within the study.