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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Stability:

Hydrolysis:

The second order hydrolysis rate constant of test chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one was determined to be  in range 0.01- 0.030 L/mol-sec . The half life of hydrolysis  of test chemical was estimated was in range of  2.0 - 7.3 years  at pH 7 and  78 - 270 days at pH 8 . These range half life of hydrolysis was indicates that test chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one is not hydrolysable.

Biodegradation:

Biodegradation in water

Biodegradation study was conducted for 21 days for evaluating the percentage biodegradability of test substance (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one by usingPseudomonas citronellolisDSM 50332 as an inoculum (Jens Harder and Christina Probian, 1995).Test inoculumPseudomonas citronellolisDSM 50332 was obtained from the Deutsche Sammlung von Mikroorganismen, Braunschweig, Germany. Initial test substance conc. used for the study was 308.5 mg/l (2 mM). Anoxic media was used for the study.The medium contained (per liter of distilled water) 1 g of NaCl, 0.1 g of MgCl2.7H2O, 0.04 g of CaCl2, 0.5 g of KCl, 0.125 g of NH4Cl, 0.2 g of Na2SO4, 0.4 g of KH2PO4, 1.2 g of K2HPO4, and 0.85 g of NaNO3. After autoclaving, 2 ml of a non-chelated trace element mixture, 2 ml of a selenite-tungstate solution, vitamins, and 20 ml of a 1 M NaHCO3 solution were added, and the pH was adjusted to 7.0.Enrichment cultures were inoculated with activated sludge obtained from a local wastewater plant (Lintel, Osterholz-Scharmbeck, Germany). Enrichment cultures were maintained and test chemical consumption was measured in 21-ml glass tubes containing 15 ml of anoxic medium (10 mM nitrate, 0.5 ml2,2,4,4,6,8,8-heptamethylnonane (HMN), and 2 mM menthone (test chemical)). The overpressure due to gas formation was measured with a syringe, and 10 mM nitrate was added when the electron acceptor was depleted. The gas formed was analyzed by gas chromatography. Bacterial growth was observed daily and required between 3 - 22 days. Monoterpene contents were determined with a gas chromatograph equipped with flame ionization detectors and connected to a digital data-analyzing system. The amounts of monoterpene dissimilated were calculated from the differences in monoterpene contents between the pasteurized controls and the grown enrichment cultures. A model MAT ITS 40 ion trap system was used for the gas chromatography-mass spectrometry analysis.Microbial growth on test chemical menthone was observed within 10 days to 3 weeks. The disappearance of test chemical in mud-free enrichment cultures was quantified.The percentage degradation of test substance (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one was determined to be 1.13% degradation by Test mat. analysis parameter in 21 days. Thus, based on percentage degradation, (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one is considered to be not readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one (CAS No. 89 -80 -5). If released in to the environment, 24.8% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.179%), indicates that (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one is not persistent in sediment.

 

Biodegradation in soil

The half-life period of (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS No.89 -80 -5) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 73.6% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one in soil is estimated to be 30 days (720 hrs). Based on this half-life value of (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Biaccumulation:

Bioaccumulation: aquatic/sediments:

The bioaccumulation study was conducted for estimating the BCF (bioaccumulation factor) value of test chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS no. 89-80-5). The bioaccumulation factor (BCF) value was calculated using a water solubility and a regression derived equation. The BCF (bioaccumulation factor) value of (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one was estimated to be 15 dimensionless, which does not exceed the bioconcentration threshold of 2000, indicating that the chemical (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one is considered to be non-accumulative in aquatic organisms.

Transport and distribution:

Adsorption/desorption:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS no. 89-80-5)was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 . The reference substances were chosen according to functional similarity with the test substance and calibration graph prepared.

The reference substances were Benzamide, Nitrobenzene, 4- Nitrobenzamide, N,N-dimethylbenzamide, N-methylbenzamide, 2 - nitrophenol having Koc value ranging from 1.239 to 2.47. The Log Koc value was determined to be 1.805 dimensionless at 25°C.

Thus based on the result it is concluded that the test substance (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one has a low sorption to soil and sediment and therefore has moderate migration potential to ground water.

Additional information

Stability:

Hydrolysis:

Half life of Hydrolysis of test chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS no. 89-80-5) was estimated by applying weight of evidence approach using experimental data from structurally and functionally similar read across chemicals. The studies are as mentioned below:

The first experimental study was reviewed from authoritative database (HSDB) in this study the half-life and base catalyzed second order hydrolysis rate constant was determined using a structure estimation method of the test chemical. The second order hydrolysis rate constant was determined to be 0.03L/mol-sec with corresponding half-lives of 7.3 yrs and 270 days at pH 7 and 8, respectively. Based on the half-life values, it is concluded that the chemical is not hydrolysable.

Next experimental study was also reviewed from same authoritative database mentioned above in this study the half-life and base catalyzed second order hydrolysis rate constant was determined using a structure estimation method of the test chemical . The second order hydrolysis rate constant was determined to be 0.01L/mol-sec with corresponding half-lives of 2 yrs and 78 days at pH 7 and 8, respectively. Based on the half-life values, it is concluded that the chemical is not hydrolysable.

By considering results of both the studies mentioned above it can be concluded that test chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS no. 89-80-5)is not hydrolysable.

Biodegradation:

Biodegradation in water:

Experimental study and predicted data for the target compound (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS No. 89-80-5) and varioussupporting studiesfor its structurally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (1995), biodegradation experiment was conducted for 21 days for evaluating the percentage biodegradability of test substance (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS no. 89-80-5) by using Pseudomonas citronellolis DSM 50332 as an inoculum. Test inoculum Pseudomonas citronellolis DSM 50332 was obtained from the Deutsche Sammlung von Mikroorganismen, Braunschweig, Germany. Initial test substance conc. used for the study was 308.5 mg/l (2 mM). Anoxic media was used for the study.The medium contained (per liter of distilled water) 1 g of NaCl, 0.1 g of MgCl2.7H2O, 0.04 g of CaCl2, 0.5 g of KCl, 0.125 g of NH4Cl, 0.2 g of Na2SO4, 0.4 g of KH2PO4, 1.2 g of K2HPO4, and 0.85 g of NaNO3. After autoclaving, 2 ml of a non-chelated trace element mixture, 2 ml of a selenite-tungstate solution, vitamins, and 20 ml of a 1 M NaHCO3 solution were added, and the pH was adjusted to 7.0.Enrichment cultures were inoculated with activated sludge obtained from a local wastewater plant (Lintel, Osterholz-Scharmbeck, Germany). Enrichment cultures were maintained and test chemical consumption was measured in 21-ml glass tubes containing 15 ml of anoxic medium (10 mM nitrate, 0.5 ml2,2,4,4,6,8,8-heptamethylnonane (HMN), and 2 mM menthone (test chemical)). The overpressure due to gas formation was measured with a syringe, and 10 mM nitrate was added when the electron acceptor was depleted. The gas formed was analyzed by gas chromatography. Bacterial growth was observed daily and required between 3 - 22 days. Monoterpene contents were determined with a gas chromatograph equipped with flame ionization detectors and connected to a digital data-analyzing system. The amounts of monoterpene dissimilated were calculated from the differences in monoterpene contents between the pasteurized controls and the grown enrichment cultures. A model MAT ITS 40 ion trap system was used for the gas chromatography-mass spectrometry analysis. Microbial growth on test chemical menthone was observed within 10 days to 3 weeks. The disappearance of test chemical in mud-free enrichment cultures was quantified. The percentage degradation of test substance (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one was determined to be 1.13% degradation by Test mat. analysis parameter in 21 days. Thus, based on percentage degradation, (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one is considered to be not readily biodegradable in nature.

 

In a prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one (CAS No. 89 -80 -5) in the presence of mixed populations of environmental microorganisms was estimated.The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one is expected to be not readily biodegradable.

 

Next study was experimental study done from from authoritative database (HSDB, 2017), in this study the biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test chemical. Activated sludge was used as a test inoculum for the study. The percentage degradation of test chemical was determined to be 0% by BOD parameter in 28 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

 

In a supporting study from authoritative database (J-CHECK and HSDB, 2017) biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test chemical. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I) under aerobic conditions. Activated sludge was used as a test inoculums for the study. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of test substance was determined to be 0% and 5% by BOD, TOC removal and GC parameter in 28 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (from peer reviewed journal and EPI suite, 2017) and for its read across substance (from authoritative database J-CHECK and HSDB, 2017), it can be concluded that the test substance (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one can be expected to be not readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one (CAS No. 89 -80 -5). If released in to the environment, 24.8% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.179%), indicates that (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one is not persistent in sediment.

 

Biodegradation in soil

The half-life period of (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS No.89 -80 -5) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 73.6% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one in soil is estimated to be 30 days (720 hrs). Based on this half-life value of (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

On the basis of available information, the test substance (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one can be considered to be not readily biodegradable in nature.

Biaccumulation:

Bioaccumulation: aquatic/sediments:

Experimental study and predicted data for the target compound (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS No. 89-80-5) and varioussupporting studiesfor its structurally similar read across substance were reviewed for the bioaccumulation end point which are summarized as below:

 

In an experimental key study from authoritative database (HSDB and Pubchem, 2017), bioaccumulation experiment was conducted for estimating the BCF (bioaccumulation factor) value of test chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS no. 89-80-5). The bioaccumulation factor (BCF) value was calculated using a water solubility and a regression derived equation. The BCF (bioaccumulation factor) value of (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one was estimated to be 15 dimensionless.

 

In aprediction done using theBCFBAF Program(v3.01) of Estimation Programs Interface (EPI Suite, 2017) was used to predict the bioconcentration factor (BCF) of test chemical (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclo hexan-1 -one (CAS No. 89-80-5). The bioconcentration factor (BCF) of (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one was estimated to be 47.8 L/kg whole body w.w (at 25 deg C).

 

Another predicted data was estimated by using Bio-concentration Factor (v12.1.0.50374) moduleACD (Advanced Chemistry Development)/I-Lab predictive module, 2017). TheBCF over the entire pH scale (pH 1 -14) of the test substance (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one (CAS no. 89 -80 -5) was estimated to be 58.2.

 

In a supporting study from authoritative database (HSDB, 2017) for the test chemical , bioaccumulation experiment was conducted on test organism Cyprinus carpio for 6 weeks for evaluating the bioconcentration factor (BCF value) of test substance under static conditions. Cyprinus carpio was used as a test organism for the study. Test chemical conc. ranges from 0.02 – 0.2 mg/l (nominal concentrations), respectively. The bioconcentration factor (BCF value) of substance (-)-Menthol on Cyprinus carpio was determined to be in the range of 1-15 at a conc. of 0.02-0.2 mg/l, respectively.

 

In next experimental study the bioaccumulation experiment was conducted on test organism Cyprinus carpio for 6 weeks for evaluating the bioconcentration factor (BCF value) of test chemical (from authoritative database J-CHECK and HSDB, 2017).The study was performed according to other guideline "Bioaccumulation test of a chemical substance in fish or shellfish" provided in "the Notice on the Test Method Concerning New Chemical Substances", respectively. Cyprinus carpio was used as a test organism for the study. Test chemical nominal conc. used for the study were 0.2 mg/land 0.02 mg/l, respectively. Test chemical solution was prepared in HCO-40. Analytical method involve the recovery ratio: Test water : 1st concentration area : 89.4 %, 2nd concentration area : 90.0 %, Fish : 74.6 %, - Limit of detection : Test water : 1st concentration area : 7.8 ng/mL, 2nd concentration area : 0.78 ng/mL, Fish : 63 ng/g. Range finding study involve theLC50(48h) 26 mg/L on Rice fish (Oryzias latipes). Lipid content of the test organism Cyprinus carpio was determined to be 4.7%. The bioconcentration factor (BCF value) of test substance on Cyprinus carpio was determined to be 0.5-15 L/Kg at a conc. of 0.2 mg/l and 4.6-11 L/Kg at a conc. of 0.02 mg/l, respectively.

 

On the basis of above results for target chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (from authoritative database HSDB, PubChem, EPI suite and ACD labs,2017) , it can be concluded that the BCF value of test substance (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one ranges from 15 –58.2 which does not exceed the bioconcentration threshold of 2000, indicating that the chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one is not expected to bioaccumulate in the food chain.

Transport and distribution:

Adsorption/desorption:

Experimental study and predicted data for the target compound (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS No. 89-80-5) and varioussupporting studiesfor its structurally similar read across substance were reviewed for the adsorption end point which are summarized as below:

In first experimental study the adsorption coefficient Koc in soil and in sewage sludge of test chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS no. 89-80-5)was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 . The reference substances were chosen according to functional similarity with the test substance and calibration graph prepared.

The reference substances were Benzamide, Nitrobenzene, 4- Nitrobenzamide, N,N-dimethylbenzamide, N-methylbenzamide, 2 - nitrophenol having Koc value ranging from 1.239 to 2.47. The Log Koc value was determined to be 1.805 dimensionless at 25°C.

Thus based on the result it is concluded that the test substance (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one has a low sorption to soil and sediment and therefore has moderate migration potential to ground water.

In next experimental study the Adsorption experiment was conducted for estimating the adsorption coefficient (Koc) value of test chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one (CAS no. 89-80-5). The adsorption coefficient (Koc) value was calculated using a water solubility of 688 mg/l and regression derived equation. The adsorption coefficient (Koc) value of test substance (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one was estimated to be 120 (Log Koc = 2.079). This Koc value indicates that the substance (2R,5S)-5 -methyl-2 -(propan-2 -yl)cyclohexan-1 -one has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

Further another adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical. The adsorption coefficient (Koc) value was calculated using a structure estimation method based on molecular connectivity indices. The adsorption coefficient (Koc) value of test substance was estimated to be 88 dimensionless (Log Koc = 1.944). This Koc value indicates that the substance has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

On the basis of above overall results for target chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one(from authoritative database HSDB, PubChem, EPI suite and ACD labs,2017) and for its read across substance (from authoritative database HSDB, 2017), it can be concluded that the Koc value of test substance (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one ranges from 120–638 indicating that the test chemical (2R,5S)-5-methyl-2-(propan-2-yl)cyclohexan-1-one has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.