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Biodegradation in water

Biodegradation study was conducted for 19 days for evaluating the percentage biodegradability of test substance 4--tert-Butylcyclohexanol (CAS no. 98-52-2) (from reveiw article Robust Summaries & Test Plans Cyclohexy Derivatives Category, 2006 and secondary source HPVIS, 2017),. The study was performed according to EG-Guideline 84/449/EWG C.3 under aerobic conditions at a temperature of 20± 2⁰C, respectively.Predominantly domestic sewage was used as a test inoculums for the study. Initial test substance conc. used in the study was 20 mg/l based on dissolved organic carbon (DOC). The percentage degradation of test substance 4-tert-Butylcyclohexanol was determined to 10% and 90% after 9 and 19 days, respectively. A 10-day window criterion is fulfilled. Thus, based on percentage degradation, 4-tert-Butylcyclohexanol is considered to be readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2018) prediction model was run to predict the half-life in water and sediment for the test compound 4-tert-butylcyclohexanol (CAS No. 98 -52 -2). If released in to the environment, 28.4% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 4-tert-butylcyclohexanol 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 4-tert-butylcyclohexanol 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 0.141%), indicates that 4-tert-butylcyclohexanol is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 4-tert-butylcyclohexanol (CAS No. 98 -52 -2) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2018). If released into the environment, 70.1% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 4-tert-butylcyclohexanol in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 4-tert-butylcyclohexanol, 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.

Additional information

Biodegradation in water

Various experimental studies and predicted data for the target compound 4-tert-Butylcyclohexanol (CAS No. 98-52-2) and supporting weight of evidence study for its structurally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental study from review article (Robust Summaries & Test Plans Cyclohexy Derivatives Category, 2006) and secondary source (HPVIS, 2017),biodegradation experiment was conducted for 19 days for evaluating the percentage biodegradability of test substance 4--tert-Butylcyclohexanol (CAS no. 98-52-2). The study was performed according to EG-Guideline 84/449/EWG C.3 under aerobic conditions at a temperature of 20± 2⁰C, respectively.Predominantly domestic sewage was used as a test inoculums for the study. Initial test substance conc. used in the study was 20 mg/l based on dissolved organic carbon (DOC). The percentage degradation of test substance 4-tert-Butylcyclohexanol was determined to 10% and 90% after 9 and 19 days, respectively. A 10-day window criterion is fulfilled. Thus, based on percentage degradation, 4-tert-Butylcyclohexanol is considered to be readily biodegradable in nature.

 

Another biodegradation study was conducted for 21 days for evaluating the percentage biodegradability of test substance 4--tert-Butylcyclohexanol (CAS no. 98-52-2) (from Handbook of Environmental Data on Organic Chemicals, 2008 and secondary source IUCLID dataset, 2000). The study was performed according to OECD Guideline 301 E "Ready biodegradability: Modified OECD Screening Test" under aerobic conditions. Predominantly domestic sewage was used as a test inoculums for the study. Initial test substance conc. used in the study was 10 mg/l based on dissolved organic carbon (DOC). The percentage degradation of test substance4-tert-Butylcyclohexanolwas determined to 89% after 21 days. Thus, based on percentage degradation, 4-tert-Butylcyclohexanol is considered to be readily biodegradable in nature.

 

In an supporting weight of evidence study from peer reviewed journal (E. Rorije, et. al, 1997),biodegradability of test substance 4-tert-Butylcyclohexanol (CAS no. 98-52-2) was estimated using the BIODEG linear and non-linear model. The models have been applied are Quantitative Structure-Activity Relationships. Two models are fitted to the judgement of an evaluation of various different biodegradation rates of chemical. This include the one using linear regression and other using a form of non-linear fitting. These models used 36 fragments as descriptors with the molecular weight of the molecule as an added descriptor, and are fitted on the evaluated biodegradation data of a series of 295 compounds. The output of the models, x, is the number that should be interpreted as x < 0.5 (=0) (Chemical biodegrades slowly or not at all) or x > 0.5 (=1) (Chemical biodegrades fast), respectively. These tests typically produce ‘biodegradable’ (1) or ‘non-biodegradable’ (0) as a result. The application of the models has been automated, the BIODEG models are incorporated in the PC-based program. As the biodegradability prediction of chemical 4-tert-Butylcyclohexanol by the BIODEG models comes out to be 1, test chemical 4-tert-Butylcyclohexanol is estimated to be readily biodegradable in nature.

 

For the target chemical4-tert-Butylcyclohexanol(CAS No. 98-52-2), Estimation Programs Interface Suite (EPI suite, 2018) was run to predict the biodegradation potential of the test compound 4-tert-butylcyclohexanol  (CAS no. 98 -52 -2) in the presence of mixed populations of environmental microorganisms. 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 4-tert-butylcyclohexanol is expected to be readily biodegradable.

 

In a supporting weight of evidence study from authoritative database (J-CHECK and HSDB, 2017) for the read across chemical Borneol (CAS no. 507-70-0),biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance Borneol (CAS no. 507-70-0). The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I) under aerobic conditions. Activated sludge (non-adapted) 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 Borneol was determined to be 97, 90 and 100% by BOD, TOC removal and GC parameter in 28 days. Thus, based on percentage degradation, Borneol is considered to be readily biodegradable in nature.

 

On the basis of above results for target chemical 4-tert-Butylcyclohexanol (from review article, secondary source HPVIS & IUCLID dataset, peer reviewed journal and modelling database EPI suite, 2018) and for its read across substance (from authoritative database J-CHECK and HSDB, 2017), it can be concluded that the test substance 4-tert-Butylcyclohexanol can be expected to be readily biodegradable in nature.

Biodegradation in water and sediment

Various predicted data for the target compound 4-tert-Butylcyclohexanol (CAS No. 98-52-2) were reviewed for the biodegradation in water and sediment end point which are summarized as below:

 

In aprediction done using the Mackay fugacity model level III of Estimation Programs Interface (EPI Suite, 2018) was run to predict the half-life in water and sediment for the test compound 4-tert-Butylcyclohexanol (CAS No. 98-52-2).If released in to the environment, 28.4% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 4-tert-butylcyclohexanol 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 4-tert-butylcyclohexanol 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 0.141%), indicates that 4-tert-butylcyclohexanol is not persistent in sediment.

 

In a supporting study from secondary source (Robust Summaries & Test Plans: Cyclohexy Derivatives Category: Revised Summaries, 2006) and HPVIS, 2017, half-life of the chemical 4 -tert-Butylcyclohexanol (CAS No: 98-52-2) in water and sediment by using Mackay EQC Fugacity Level III. The following values has been used in the Mackay EQC Fugacity Level III for the estimating the half-life value. They are water solubility: 100 mg/l, vapour pressure: 0.0075 mm Hg, log Kow: 3.23 and melting point: 55-70°C, respectively. If released into the environment, 38.1% of the chemical will partition into water according to the Mackay EQC Fugacity Level III and the half-life period of 4 -tert-Butylcyclohexanol in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by Mackay EQC Fugacity Level III) indicates that the chemical 4-tert-Butylcyclohexanol is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 4-tert-Butylcyclohexanol in sediment is estimated to be 60 days (1440 hrs). Based on this half-life value of test chemical 4-tert-Butylcyclohexanol, it is concluded that the chemical 4-tert-Butylcyclohexanol is not persistent in the sediment environment and the exposure risk to soil dwelling animals is moderate to low.

 

On the basis of above results for target chemical 4-tert-Butylcyclohexanol (from EPI suite, 2018 and secondary source), it can be concluded that the test substance 4-tert-Butylcyclohexanol is not persistent in the water and sediment environment and therefore the exposure risk to aquatic and soil dwelling animals is moderate to low.

Biodegradation in soil

Various predicted data for the target compound 4-tert-Butylcyclohexanol (CAS No. 98-52-2) were reviewed for the biodegradation in soil end point which are summarized as below:

 

The half-life period of 4-tert-butylcyclohexanol (CAS No. 98 -52 -2) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2018). If released into the environment, 70.1% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 4-tert-butylcyclohexanol in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 4-tert-butylcyclohexanol, 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.

 

In a supporting study from secondary source (Robust Summaries & Test Plans: Cyclohexy Derivatives Category: Revised Summaries, 2006) and HPVIS, 2017,half-life of the chemical 4-tert-Butylcyclohexanol (CAS No: 98-52-2) in soil by using Mackay EQC Fugacity Level III. The following values has been used in the Mackay EQC Fugacity Level IIIfor the estimating the half-life value. They are water solubility: 100 mg/l, vapour pressure: 0.0075 mm Hg, log Kow: 3.23 and melting point: 55-70°C, respectively. If released into the environment, 59.1% of the chemical will partition into soil according to the Mackay EQC Fugacity Level III. The half-life period of 4 -tert-Butylcyclohexanol in soil is estimated to be 15 days (360 hrs). Based on this half-life value of test chemical 4-tert-Butylcyclohexanol, it is concluded that the chemical 4-tert-Butylcyclohexanol is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

 

On the basis of above results for target chemical 4-tert-Butylcyclohexanol (from EPI suite, 2018 and secondary source), it can be concluded that the test substance 4-tert-Butylcyclohexanol is not persistent in the soil environment and therefore the exposure risk to soil dwelling animals is moderate to low.

On the basis of available information, the test substance 4-tert-Butylcyclohexanol can be considered to be readily biodegradable in nature.