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Environmental fate & pathways

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Description of key information

Hydrolysis

The estimated half-life of 2-isopropyl-5-methylcyclohexanone was estimated to be 122.28 days, indicating that it is very negligibly hydrolysable.

Biodegradation in water

Biodegradability of 2 -isopropyl-5 -methylcyclohexanone (CAS no. 1074-95-9) is predicted using OECD QSAR toolbox version 3.4 (2017). Test substance undergoes 31.60% degradation by CO2 evolution parameter in 28 days. Thus, based on percentage degradation, the test chemical 2 -isopropyl-5 -methylcyclohexanone was estimated to be not readily biodegradable in water.

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 2 -isopropyl-5 -methyl cyclohexanone (CAS No.1074 -95 -9). 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 test chemical 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 test chemical 2 -isopropyl-5 -methylcyclohexanone 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 2 -isopropyl-5 -methylcylcohexanone is not persistent in nature.

Biodegradation in soil

The half-life period of 2 -isopropyl-5 -methylcyclohexanone (CAS No. 1074 -95 -9) 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, 73.8% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 2 -isopropyl-5 -methylcyclohexanone in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 2 -isopropyl-5 -methylcyclohexanone, 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.

Bioaccumulation: aquatic / sediment:

The estimated bio concentration factor (BCF) for 2-isopropyl-5-methylcyclohexanone is 47.8 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000.Thus it is concluded that 2-isopropyl-5-methylcyclohexanone is not expected to bio accumulate in the food chain.

Adsorption / desorption:

The adsorption coefficient Koc in soil and in sewage sludge (±)-menthone(CAS No.1074-95-9) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No.121 for testing of Chemicals. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances chosen were 4 -chloroaniline, 4-methylaniline, N-methylaniline, 2 - nitrophenol, Nitrobenzene, 4-Nitrobenzamide, N,Ndimethylbenzamide,N-methylbenzamide and Benzamide, having Koc value ranging from 1.239 to 2.47. The Log Koc value was found to be 2.629 ± 0.0005at 25°C.

Additional information

Hydrolysis

Hydrolysis of 2-isopropyl-5-methylcyclohexanone was predicted using OECD QSAR toolbox version 3.4 (2017). The estimated half-life of 2-isopropyl-5-methylcyclohexanone was estimated to be 122.28 days. This value indicates that 2-isopropyl-5-methylcyclohexanone is very negligibly hydrolysable.

Biodegradation in water

Various predicted data for the target compound 2-isopropyl-5-methylcyclohexanone (CAS No. 1074-95-9) and 3 supporting studies (1 study from authoritative database and 2 studies from secondary source) for its closest read across substance with logKow as the primary descriptor were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2017) by usingQSAR toolbox version 3.4 with logKow as the primary descriptor, percentagebiodegradability of test chemical 2 -isopropyl-5 -methylcyclohexanone (CAS no. 1074-95-9) was estimated. Test substance undergoes 31.60% degradation by CO2 evolution parameter in 28 days. Thus, based on percentage degradation, the test chemical 2-isopropyl-5-methylcyclohexanone was estimated to be not readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound 2 -isopropyl-5 -methylcyclohexano ne (CAS no. 1074 -95 -9) 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 2 -isopropyl-5 -methylcyclohexanone is expected to be not readily biodegradable.

 

Biodegradation study was conducted for 20 days for evaluating the percentage biodegradability of read across substance Dipropylene glycol monomethyl ether (CAS no. 34590-94-8) (HSDB, 2016). The percentage degradation of read across substance was determined to 0, 0 and 31% degradation by ThOD parameter in 5, 10 and 20 days, respectively. Thus, based on percentage degradation, Dipropylene glycol monomethyl ether was considered to be not readily biodegradable in nature.

 

Another weight of evidence study of biodegradation was conducted for 28 days for evaluating the percentage biodegradability of read across substance Dipropylene glycol monomethyl ether (CAS no. 34590-94-8) (OECD SIDS, 2001). Initial test substance conc. used in the study was10 mg/l, respectively. The percentage degradation of read across substance was determined to be 34% degradation in 28 days. At a concentration of 20 mg/l degradation was <10% after 28 days. Thus, based on percentage degradation, Dipropylene glycol monomethyl ether was considered to be not readily biodegradable in nature.

 

In addition to the above weight of evidence studies, another biodegradation study of read across substance Dipropylene glycol monobutyl ether (CAS no. 29911-28-2) from secondary source (OECD SIDS, 2003), was carried out for 28 days for evaluating the percentage biodegradability of read across substance Dipropylene glycol monobutyl ether. The study was performed according to OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test). Initial test substance conc. used in the study was 0, 1.86, or 9.29 mg/l, respectively. Domestic sewage was used as a test inoculum collected from a local municipal sewage treatment facility. To test for its ready biodegradability potential, read across chemical was incubated for 28 days in continuously agitated closed bottles in the dark at two concentrations with inoculum (secondary effluent) collected from a local municipal sewage treatment facility. The incubation temperature of the water was 19.7-20.0°C, pH ranged from 7.2 to 7.4, hardness was not reported, and the concentration of inoculum was one droplet per liter of test solution. Oxygen concentration was the measured variable. Degradation of read across chemical was monitored by assessing the dissipation of oxygen in the test solution over time (i.e., measuring dissolved oxygen content with an oxygen electrode at various time points). Oxygen content was measured (in duplicate bottles) on days 0, 5, 15, and 28. Degradation was calculated by dividing the biochemical oxygen demand (BOD) expressed as mg O2 per mg DPnB, by the theoretical oxygen demand (ThOD).The percentage degradation of read across substance was determined to be 0% by %ThOD parameter in 28 days. Thus, based on percentage degradation, Dipropylene glycol monobutyl ether was considered to be not readily biodegradable in water.

 

On the basis of above results for target chemical 2-isopropyl-5-methylcyclohexanone (study 1, 2 from OECD QSAR toolbox 3.4 and EPI suite) and for its read across substance (study 3 from authoritative database HSDB and study 4 and 5 from secondary source), it can be concluded that the test substance 2 -isopropyl-5 -methylcyclohexanone 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 2 -isopropyl-5 -methyl cyclohexanone (CAS No.1074 -95 -9). 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 test chemical 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 test chemical 2 -isopropyl-5 -methylcyclohexanone 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 2 -isopropyl-5 -methylcylcohexanone is not persistent in nature.

Biodegradation in soil

The half-life period of 2 -isopropyl-5 -methylcyclohexanone (CAS No. 1074 -95 -9) 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, 73.8% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 2 -isopropyl-5 -methylcyclohexanone in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 2 -isopropyl-5 -methylcyclohexanone, 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 substance2-isopropyl-5-methylcyclohexanonecan be considered to be not readilybiodegradable in nature.

Bioaccumulation: aquatic / sediment:

Five studies including Predicted model data and Experimental result for Bioaccumulation endpoint of target chemical 2-isopropyl-5-methylcyclohexanone (Cas no. 1074-95-9) and its relevant read across chemical which is100% structurally similar to targetwere reviewed to summarize as follows:  

 

In a prediction done using the BCFBAF (v3.01) model of the EPI suite Program (2017), the estimated bio concentration factor (BCF) for target chemical 2-isopropyl-5-methylcyclohexanone is 47.8 L/kg wet-wt.

Another prediction model PBT profiler; 2017 indicated that the Bioaccumulation factor (BCF) was predicted to be 48 L/kg wet-wt at 25 deg.C for 2-isopropyl-5-methylcyclohexanone.

 

Further, as per Chemspider - ACD/PhysChem Suite prediction model, the Bioconcentration factor (BCF) for target chemical 2-isopropyl-5-methylcyclohexanone was predicted to be 147.25 at pH 5.5 and 7.4 at temperature 25 deg.C.

 

Above all results are supported by reliable prediction database i.e Scifinder; 2017 for read across substance trans-menthone (Cas no. 89-80-5) indicated the Bioconcentration factor (BCF) for was predicted to be 73.1 at pH 1-10 and temperature 25 deg.C.

 

In addition, a study from authorative database i.e HSDB by US EPA; 2017 for same read across chemical i.e trans-menthone (Cas no. 89-80-5) indicated an estimated BCF of 15 was calculated for menthone, using a water solubility of 688 mg/l and a regression derived equation. This BCF suggests the potential for bioconcentration in aquatic organisms is low.

All studies for target and read across indicate the BCF factor is in the range of 15 -147.25(L/kg wet-wt or dimensionless) concluded test substance chemical 2-isopropyl-5-methylcyclohexanone (Cas no. 1074-95-9) is non Bioaccumulative in aquatic environment as all not exceed the BCF criteria of 2000.

Adsorption / desorption:

Five studies including Experimental result and Predicted model data for Adsorption endpoint of target chemical 2-isopropyl-5-methylcyclohexanone (Cas no. 1074-95-9) and its relevant read across chemical which is 100% structurally similar to target were reviewed to summarize as follows:  

 

First key study from experimental study result performed by UERL lab;2017 which suggest the adsorption coefficient Koc in soil and in sewage sludge (±)-menthone(CAS No.1074-95-9) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No.121 for testing of Chemicals. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances chosen were 4 -chloroaniline, 4-methylaniline, N-methylaniline, 2 - nitrophenol, Nitrobenzene, 4-Nitrobenzamide, N,Ndimethylbenzamide,N-methylbenzamide and Benzamide, having Koc value ranging from 1.239 to 2.47. The Log Koc value was found to be 2.629 ± 0.0005at 25°C.

And Estimation from EPI suite Program using KOCWIN (v2.00) model indicated Soil Adsorption Coefficient i.e Koc value of 2-isopropyl-5-methylcyclohexanone was estimated as Koc 136.2 L/kg (log Koc=2.134)  by means of MCI method at 25 deg.C. This Koc value indicates that the substance 2-isopropyl-5-methylcyclohexanone has a low sorption to soil and sediment and therefore have moderate migration potential to groundwater.

 

Whereas from chemspider prediction database, the soil adsorption coefficient i.e Koc value of test substance 2-isopropyl-5-methylcyclohexanone was estimated to be 1240.21 i.e Log Koc= 3.093 at pH 5.5 and 7.4 at temp.25 deg.C .This Koc value indicates that the substance 2-isopropyl-5-methylcyclohexanone has a low sorption to soil and sediment and therefore have moderate migration potential to groundwater.

 

Above both predicted results are supported by experimental data from HSDB database; (2017) for the read across chemical menthone (Cas no. 89-80-5), using a water solubility of 688 mg/l and a regression derived equation, which indicate the Koc of menthone is estimated as approximately 120.This estimated Koc value suggests that menthone is expected to have high mobility in soil.

 

Whereas SciFinder, American Chemical Society (ACS); 2017 predicted database for same read across i.e menthone (Cas no. 89-80-5) indicate the soil adsorption coefficient i.e Koc value was estimated to be 751 i.e Log Koc= 2.875 at pH range 1-10 and temperature 25 deg.C. This Koc value at all range of pH condition indicates that the substance Methanone has a low sorption to soil and sediment and therefore have moderate migration potential to groundwater.

 

Thus based on the above all available studies for target and read across chemical gives the common conclusion that the test substance 2-isopropyl-5-methylcyclohexanone (Cas no. 1074-95-9) has high to moderate mobility in soil/sediment.