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Environmental fate & pathways

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Description of key information

Hydrolysis

HYDROWIN v2.00 program of Estimation Programs Interface (EPI Suite, 2017) prediction model was used to predict the hydrolysis half-life of test compound 3-Methylbutyl propanoate (CAS No. 105 -68 -0). The estimated half-life of 3-Methylbutyl propanoate was estimated to be 2.537 years at pH 7.0 and 92.679 days at pH 8.0 (at 25 deg C), indicating that it is not hydrolysable.

Biodegradation in water

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance 3-Methylbutyl propanoate (CAS no. 105-68-0) (A.M. Api, et. al; 2017).

The study was performed according to OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test).The percentage degradation of test substance 3-Methylbutyl propanoate was determined to be 74% by O2 consumption parameter in 28 days. Thus, based on percentage degradation, 3-Methylbutyl propanoate is considered to be 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 3-Methylbutyl propanoate (CAS No. 105 -68 -0). If released in to the environment, 35.4% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 3-Methylbutyl propanoate 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 3-Methylbutyl propanoate 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 0.144%), indicates that 3-Methylbutyl propanoate is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 3-Methylbutyl propanoate (CAS No. 105 -68 -0) 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, 52.5% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 3-Methylbutyl propanoate in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 3-Methylbutyl propanoate, 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

BCFBAF model (v3.01) of Estimation Programs Interface (EPI Suite, 2017) was used to predict the bioconcentration factor (BCF) of test chemical 3-Methylbutyl propanoate (CAS No. 105 -68 -0). The bioconcentration factor (BCF) of 3 -Methylbutyl propanoate was estimated to be 30.54 L/kg whole body w.w (at 25 deg C) which does not exceed the bio concentration threshold of 2000, indicating that the chemical 3-Methylbutyl propanoate is not expected to bioaccumulate in the food chain.

Adsorption/desorption

KOCWIN model (v2.00) of Estimation Programs Interface (EPI Suite, 2017) was used to predict the soil adsorption coefficient i.e Koc value of test chemical 3-Methylbutyl propanoate (CAS No. 105 -68 -0). The soil adsorption coefficient i.e Koc value of 3-Methylbutyl propanoate was estimated to be 54.22 L/kg (log Koc=1.7341)  by means of MCI method (at 25 deg C). This Koc value indicates that the substance 3-Methylbutyl propanoate has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

Additional information

Hydrolysis

Predicted data for the target chemical 3-Methylbutyl propanoate (CAS No. 105-68-0) and various supporting weight of evidence studies from authoritative database for its read across substance were reviewed for the hydrolysis end point which are summarized as below:

 

In a prediction using the HYDROWIN v2.00 program of Estimation Programs Interface (EPI Suite, 2017) prediction model, the hydrolysis half-life of test compound 3-Methylbutyl propanoate (CAS No. 105 -68 -0) was estimated. The estimated half-life of 3-Methylbutyl propanoate was evaluated to be 2.537 years at pH 7.0 and 92.679 days at pH 8.0 (at 25 deg C), indicating that it is not hydrolysable.

 

In a supporting weight of evidence study from authoritative database (HSDB, 2017) for the read across chemical 3-methyl-1-butyl acetate (CAS no. 123-92-2), the half-life and base catalyzed second order hydrolysis rate constant was determined using a structure estimation method of the read across chemical 3-methyl-1-butyl acetate. The second order hydrolysis rate constant of 3-methyl-1-butyl acetate was determined to be 0.1L/mol-sec with a corresponding half-lives of 2 yrs and 78 days at pH 7 and 8, respectively.

 

For another read across chemical Ethyl propanoate (CAS no. 105-37-3), the half-life and base catalyzed second order hydrolysis rate constant was determined of the read across chemical Ethyl propanoate. The second order hydrolysis rate constant of Ethyl propanoate was determined to be 0.089L/mol-sec with a corresponding half-lives of 2.5 yrs and 90 days at pH 7 and 8, respectively.

 

In a supporting weight of evidence study from authoritative database (HSDB, 2017) for the read across chemical 2-methylpropyl 2-methylprop-2-enoate (CAS no. 97-86-9), the half-life and base catalyzed second order hydrolysis rate constant was determined using a structure estimation method of the read across chemical 2-methylpropyl 2-methylprop-2-enoate. The second order hydrolysis rate constant of 2 -methylpropyl 2 -methylprop-2 -enoate was determined to be 0.018L/mol-sec with a corresponding half-lives of 130 and 13 yrs at pH 7 and 8, respectively.

 

On the basis of the above results for target chemical 3-Methylbutyl propanoate (from EPI Suite, 2017) and for its read across substance (from authoritative databaseHSDB, 2017), it can be concluded that the test chemical 3-Methylbutyl propanoate is not hydrolysable.

Biodegradation in water

Experimental and predicted data for the target compound 3-Methylbutyl propanoate (CAS No. 105-68-0) and various supporting studies for its read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (A.M. Api, et. al; 2017), biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test substance 3-Methylbutyl propanoate (CAS no. 105-68-0). The study was performed according to OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test).The percentage degradation of test substance 3-Methylbutyl propanoate was determined to be 74% by O2 consumption parameter in 28 days. Thus, based on percentage degradation, 3-Methylbutyl propanoate is considered to be readily biodegradable in nature.

 

In a prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound 3-Methylbutyl propanoate (CAS No. 105-68-0) 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 3-Methylbutyl propanoate is expected to be readily biodegradable.

 

In a supporting study from peer reviewed journal (Kenneth S. Price, et. al; 1974) and authoritative database (HSDB, 2017) for the read across chemical 2-methyl propyl acetate (CAS no. 110-19-0), biodegradation experiment was conducted for 20 days for evaluating the percentage biodegradability of read across substance 2-methyl propyl acetate (CAS no. 110-19-0). Initial test substance conc. used in the study was 3, 7 and 10 mg/l, respectively. Domestic wastewater was used as a test inoculum. The BOD bottles were half filled with aerated dilution water containing the specified minerals and buffer. Small aliquots of the test chemicals were added to these bottles from 0.1% stock solutions yielding conc. of 3, 7 and 10 mg/l. At least two of these concentrations were tested in duplicate. These concentrations gave a potential oxygen demand of 3 to 30 mg/l over the 20 days duration of test. Dissolved oxygen was monitored periodically in the individual bottles through the use of a commercial DO meter filled with an agitated probe. The bottles were opened for sampling and DO measurements about five times during the course of the 20 day test. The percentage degradation of substance 2-methyl propyl acetate was determined to be 60, 74, 79 and 81% in 5, 10, 15 and 20 days, respectively. Thus, based on percentage degradation, 2-methyl propyl acetate is considered to be readily biodegradable in nature.

 

Another biodegradation study was conducted for 14 days for evaluating the percentage biodegradability of read across substance 3-methylbutyl 2-hydroxybenzoate (CAS no. 87-20-7) (J-CHECK, 2017 and Envichem, 2014). The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)). 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 substance 3-methylbutyl 2-hydroxybenzoate was determined to be 83.4 and 100% by BOD and GC parameter in 14 days. Thus, based on percentage degradation, 3-methylbutyl 2-hydroxybenzoate is considered to be readily biodegradable in nature.

 

For the read across substance 2-methylpropyl 2-methylprop-2-enoate (CAS no. 97-86-9) from authoritative database (HSDB, 2017), biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance 2-methylpropyl 2-methylprop-2-enoate. The study was performed according to OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test) under aerobic conditions. Sewage was used as a test inoculum for the study. The percentage degradation of substance 2-methylpropyl 2-methylprop-2-enoate was determined to be 74% by O2 consumption parameter in 28 days. Thus, based on percentage degradation, 2-methylpropyl 2-methylprop-2-enoate is considered to be readily biodegradable in nature.

 

In a supporting study from authoritative database (HSDB, 2017) for the read across chemical butyl 2-hydroxypropanoate (CAS no. 138-22-7),biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance butyl 2-hydroxypropanoate. The study was performed according to OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test) under aerobic conditions. Activated sludge was used as a test inoculum for the study. Initial test substance conc. used were1.53, 2.0 and 2.08 mg/l, respectively. The percentage degradation of substance butyl 2-hydroxypropanoate was determined to be 22, 39 and 25% in 5 days and 57, 63 and 69% after 28, 20 and 28, respectively by using O2 consumption parameter. Thus, based on percentage degradation, butyl 2-hydroxypropanoate is considered to be readily biodegradable in nature.

 

On the basis of above results for target chemical 3-Methylbutyl propanoate (from peer reviewed journal and EPI suite, 2017) and for its read across substance (from peer reviewed journal, authoritative database J-CHECK, HSDB and Envichem, 2014), it can be concluded that the test substance 3-Methylbutyl propanoate can be expected to be 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 3-Methylbutyl propanoate (CAS No. 105 -68 -0). If released in to the environment, 35.4% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 3-Methylbutyl propanoate 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 3-Methylbutyl propanoate 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 0.144%), indicates that 3-Methylbutyl propanoate is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 3-Methylbutyl propanoate (CAS No. 105 -68 -0) 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, 52.5% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 3-Methylbutyl propanoate in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 3-Methylbutyl propanoate, 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 3-Methylbutyl propanoate can be considered to be readily biodegradable in nature.

Bioaccumulation: aquatic/sediment

Various predicted data for the target compound 3-Methylbutyl propanoate (CAS No. 105-68-0) and supporting weight of evidence study for its read across substance were reviewed for the bioaccumulation end point which are summarized as below:

 

In aprediction done using the BCFBAF Program (v3.01) of Estimation Programs Interface (EPI Suite, 2017) was used to predict the bioconcentration factor (BCF) of test chemical 3-Methylbutyl propanoate (CAS No. 105 -68 -0). The bioconcentration factor (BCF) of 3 -Methylbutyl propanoate was estimated to be 30.54 L/kg whole body w.w (at 25 deg C).

 

In an another prediction done 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 0 -14) of the test substance 3-Methylbutyl propanoate (CAS no. 105 -60 -8) was estimated to be 60.8.

 

Bioconcentration Factor (BCF) of test chemical 3-Methylbutyl propanoate (CAS no. 105 -68 -0) was estimated using Chemspider database(ChemSpider, 2017). The bioconcentration factor of test substance 3-Methylbutyl propanoate was estimated to be 40.51 at both pH 5.5 and 7.4, respectively.

 

Another predicted data was estimated usingSciFinder database (American Chemical Society (ACS), 2017) was used for predicting the bioconcentration factor (BCF) of test chemical 3-Methylbutyl propanoate (CAS No. 105 -68 -0). The bioconcentration factor (BCF) of 3-Methylbutyl propanoate was estimated to be 62.7 (at 25 deg C).

 

From CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application) V1.02 model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical), the bioaccumulation i.e BCF for test substance 3-Methylbutyl propanoate was estimated to be 6.10 dimensionless. The predicted BCF result based on the 5 OECD principles. Thus based on the result it is concluded that the test substance 3-Methylbutyl propanoate is non-bioaccumulative in nature.

 

In a supporting weight of evidence study from authoritative database (HSDB, 2017) for the read across chemical 3-methyl-1-butyl acetate (CAS no. 123-92-2), bioaccumulation experiment in fish was conducted for estimating the BCF (bioaccumulation factor) value of read across chemical 3 -methyl-1-butyl acetate. The bioaccumulation factor (BCF) value was calculated using a log Kow of 2.25 and a regression equation. The estimated BCF (bioaccumulation factor) value of 3-methyl-1-butyl acetate in fish was determined to be 14 dimensionless.

 

For the read across chemical Ethyl propanoate (CAS no. 105-37-3), the bioaccumulation study was conducted for estimating the BCF (bioaccumulation factor) value of read across substance Ethyl propanoate. The bioaccumulation factor (BCF) value was calculated using a log Kow of 1.21 and a regression equation. The estimated BCF (bioaccumulation factor) value of Ethyl propanoate was determined to be 1.7 dimensionless.

 

On the basis of above results for target chemical 3-Methylbutyl propanoate (from EPI suite, ACD labs,ChemSpider, SciFinder database and CompTox Chemistry Dashboard,  2017) and for its read across substance (from authoritative database HSDB, 2017), it can be concluded that the BCF value of test substance 3-Methylbutyl propanoate ranges from 6.10 – 60.8 which does not exceed the bioconcentration threshold of 2000, indicating that the chemical 3-Methylbutyl propanoate is not expected to bioaccumulate in the food chain.

Adsorption/desorption

Various predicted data for the target compound 3-Methylbutyl propanoate (CAS No. 105-68-0) and supporting weight of evidence study for its read across substance were reviewed for the adsorption end point which are summarized as below:

 

In a prediction done using the KOCWIN Program(v2.00) of Estimation Programs Interface (EPI Suite, 2017) was used to predict the soil adsorption coefficient i.e Koc value of test chemical 3-Methylbutyl propanoate (CAS No. 105 -68 -0). The soil adsorption coefficient i.e Koc value of 3-Methylbutyl propanoate was estimated to be 54.22 L/kg (log Koc=1.7341) by means of MCI method (at 25 deg C). This Koc value indicates that the substance 3-Methylbutyl propanoate has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

The Soil Adsorption Coefficient i.e Koc value of test substance 3-Methylbutyl propanoate (CAS no. 105 -68 -0) was estimated using Adsorption Coefficient module (v12.1.0.50374) program as Koc 658 (log Koc = 2.8 ± 1.0) at pH range 1-14 respectively(ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017).. This Koc value indicates that the test substance 3-Methylbutyl propanoate has a moderate sorption to soil and therefore have slow migration potential to groundwater.

 

In an another prediction done by using ChemSpider Database (2017), the Soil Adsorption Coefficient i.e Koc value of test substance 3-Methylbutyl propanoate (CAS no. 105 -68 -0) was estimated. The adsorption coefficient (Koc) value of substance 3-Methylbutyl propanoate was estimated to be 492.37 (Log Koc = 2.692) at pH 5.5 and 7.4, respectively. This Koc value indicates that the substance 3-Methylbutyl propanoate has a moderate sorption to soil and sediment and therefore have slow migration potential to groundwater.

 

Additional soil adsorption coefficient i.e Koc value of test chemical 3-Methylbutyl propanoate (CAS No. 105 -68 -0) was estimated using the SciFinder database (American Chemical Society (ACS), 2017).The soil adsorption coefficient i.e Koc value of 3-Methylbutyl propanoate was estimated to be 673 (log Koc = 2.828) (at 25 deg C). This Koc value indicates that the substance 3-Methylbutyl propanoate has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

 

From CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application) V1.02 model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical), the adsorption coefficient i.e KOC for test substance 3-Methylbutyl propanoate (CAS no. 105 -68 -0) was estimated to be 80.6 L/kg (log Koc = 1.90).The predicted KOC result based on the 5 OECD principles. This Koc value indicates that the substance 3-Methylbutyl propanoate has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

In a supporting weight of evidence study from authoritative database (HSDB, 2017) for the read across chemical 3-methyl-1-butyl acetate (CAS no. 123-92-2), adsorption experiment was conducted for estimating the adsorption coefficient (Koc) value of read across chemical 3-methyl-1-butyl acetate. The adsorption coefficient (Koc) value was calculated using a measured logKow of 2.25 and a regression derived equation. The adsorption coefficient (Koc) value of substance 3-methyl-1-butyl acetate was estimated to be 130 (Log Koc = 2.113). This Koc value indicates that the substance 3-methyl-1-butyl acetate has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

For another read across chemical 2-methylpropyl prop-2-enoate (CAS no. 106-63-8), adsorption study was conducted for estimating the adsorption coefficient (Koc) value of read across chemical 2-methylpropyl prop-2-enoate. The adsorption coefficient (Koc) value was calculated using a water solubility of 2000 mg/l and a regression derived equation. The adsorption coefficient (Koc) value of substance 2 -methylpropyl prop-2 -enoate was estimated to be 66 (Log Koc = 1.819). This Koc value indicates that the substance 2 -methylpropyl prop-2 -enoate 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 3-Methylbutyl propanoate (from EPI suite, ACD labs,ChemSpider, SciFinder database and CompTox Chemistry Dashboard,2017) and for its read across substance (from authoritative database HSDB, 2017), it can be concluded that the Koc value of test substance 3-Methylbutyl propanoate ranges from 54.22 –673 indicating that the test chemical 3-Methylbutyl propanoate has a low to moderate sorption to soil and sediment and therefore have moderate to slow migration potential to ground water.