Phenethyl valerate

Endpoint summary

Description of key information

Biodegradation in water:

Biodegradability of test chemical 2-phenylethyl pentanoate was predicted by using OECD QSAR tool box v3.4 with log Kow as primary descriptor. The target chemical 2-phenylethyl pentanoate undergoes 93.166 % degradation by considering BOD as parameter and Microorganisms as inoculum in 28 days. Based on percent degradation value it is concluded that this test chemical is readily biodegradable.

Biodegradation in water and sediments:

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound 2-phenylethyl pentanoate(CAS No. 7460 -74 -4). If released in to the environment, 23.9 % 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 be15 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 low whereas the half-life period of test chemical 2-phenylethyl pentanoate in sediment is estimated to be135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 2 % (i.e, reported as 1.08 %), indicates that test chemical 2-phenylethyl pentanoate is not persistent in sediment.

Biodegradation in soil:

The half-life period of test chemical 2-phenylethyl pentanoate (CAS No. 7460 -74 -4) 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, 73.2 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical 2-phenylethyl pentanoate in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical 2-phenylethyl pentanoate, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is low .

Additional information

Biodegradation in water:

Predicted data for the target compound 2-phenylethyl pentanoate and supporting weight of evidence studies for its read across substance were reviewed for the biodegradation end point which are summarized as below:

Biodegradability of test chemical 2-phenylethyl pentanoate was predicted by using OECD QSAR tool box v3.4 with log Kow as primary descriptor. The target chemical 2-phenylethyl pentanoate undergoes 93.166 % degradation by considering BOD as parameter and Microorganisms as inoculum in 28 days. Based on percent degradation value it is concluded that this test chemical is readily biodegradable.

 

Another prediction was done by using Estimation Programs Interface Suite (EPI suite, 2017)to determine the biodegradation potential of the test compound 2-phenylethyl pentanoate (CAS no. 7460 -74 -4) 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 2-phenylethyl pentanoate is expected to be readily biodegradable.

 

In a supporting weight of evidence study for read across chemical benzyl acetate from Chemophere journal the biodegradation study was conducted for 28 days(4 weeks) for evaluating the percentage biodegradability of the test substance using the OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) and Other guideline: New Biodegradability Test developed. The Sturm method was used in conjunction to validate the results of the new method.

The test was performed under aerobic conditions using activated sludge as an inoculum with conc. of 30 mg/l and initial test substance conc. is 10 mg/l (ranges from 2 – 10 mg/l). The read across substance in a dilute mineral salts solution is incubated in sealed vessels with appropriate micro-organisms for a period of up to 28 days. Controls containing the 0.5 to 10% inoculum concentration, without read across chemical are also prepared.

A vessel is removed from the shaker as required, a sample of the headspace gas withdrawn using a gas syringe and the concentration of carbon dioxide determined. The seal is then broken and the concentration of dissolved inorganic carbon (DIC) in the solution is measured immediately, Similar determinations are made for a control vessel which does not contain the read across substance. The difference in the total inorganic carbon found in the test and control vessels allows the quantity of carbon dioxide produced from the test compound to be ascertained.

The determination of carbon dioxide in both gaseous and aqueous samples was performed using a modified Ionics 555 TC-T°C Analyser. Carbon dioxide is released from aqueous samples of carbonate/bicarbonate by direct injection using a 0-200 µl Hamilton constant rate syringe onto an inert support loaded with phosphoric acid. The temperature in the reaction chamber is controlled at 150°C and pure nitrogen is used as the carrier gas. The detection system is a high sensitivity non-dispersive infra-red analyser. Gaseous samples are injected using a good quality gastight syringe.

A preliminary study was conducted using 2 mg/L of test substance conc. The percentage biodegradation of read across substance was determined to be 100.9% with standard deviation of 2.5 and 95% confidence interval of 96.9 – 104.9. Thus, the read across substance benzyl acetate was determined to be readily biodegradable.

 

 

In another weight of evidence study for read across chemical 2 -phenylethyl propanoate from Pest management Science journal ( 2008) the Biodegradation experiment was conducted for 30 days for evaluating the percentage biodegradability of read across substance 2 -phenylethyl propanoate. Pond water was used as a test inoculum collected from the Iowa State University Horticulture Farm pond (Ames, IA, USA). Initial test substance conc. used for the study was 10μg/g. The pH of the water was 7.3, the alkalinity was 91 mg/ml, and the total hardness was 182 mg/ml. Pond water (100 ml) was kept in French square bottles and spiked with 3H-PEP in 300 μl of acetone carrier solvent to result in a concentration of 10 μg/ml. The samples were incubated in dark and in light separately, and were maintained at a constant temperature of 25 ± 2°C throughout the study in the environmental chamber. Aluminum foil wrapping was used to prevent “dark” incubations from having exposure to light. Samples were taken at days 0, 0.25, 0.5, 1, 3, 7, 14, 21 and 30 post-treatment. Quantitative analysis of PEP was performed using a Hewlett-Packard (Palo Alto, CA, USA) series 1100 HPLC system with a quaternary pump, an autosampler, a thermostatted column compartment, and a Spectroflow 757 absorbance detector (ABI Analytical, Kratos Division, Ramsey, NJ, USA). Data were collected and analyzed using HP Chemstation system software (REV. A.04.01). An Alltech Adsorbosphere® (Deerfield, IL, USA) C18 column (4.6×250 mm, 5-μm particle size) was used. Detection was conducted at 270 nm with a flow rate of 1.0 ml/min at room temperature. The mobile phase was methanol/distilled water (70:30, v/v).Dissipation rates of PEP were calculated using first-order open models. A student’s-test was used to compare dissipation rates of PEP in light and in dark from the water dissipation studies. Dissipation of PEP in water was very rapid with a DT 50 of 5 days. Volatility loss was negligible in one month with mass balance from 96% to 100%. The primary degradation product was 2-phenylethanol, which was produced from ester hydrolysis of phenethyl propionate; another degradation product was 2-(4-hydroxyphenyl) ethanol, which was probably a biotransformation product of 2-phenylethanol in microbes. The percentage degradation of read across substance 2-phenylethyl propanoate was determined to be 50% in 5 days. Thus, based on percentage degradation, 2-phenylethyl propanoate is considered to be readily biodegradable in nature.

 

On the basis of results of above mentioned studies for target chemical 2-phenylethyl pentanoate (CAS No. 7460-74-4) (from OECD QSAR tool box v3.4 and EPI suite) and supporting weight of evidence study (from chemosphere and Pest management Science journal). It is concluded that the test chemical 2-phenylethyl pentanoat ecan be expected to be readily biodegradable.

Biodegradation in water and sediments:

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound 2-phenylethyl pentanoate(CAS No. 7460 -74 -4). If released in to the environment, 23.9 % 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 be15 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 low whereas the half-life period of test chemical 2-phenylethyl pentanoate in sediment is estimated to be135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 2 % (i.e, reported as 1.08 %), indicates that test chemical 2-phenylethyl pentanoate is not persistent in sediment.

Biodegradation in soil:

The half-life period of test chemical 2-phenylethyl pentanoate (CAS No. 7460 -74 -4) 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, 73.2 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical 2-phenylethyl pentanoate in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical 2-phenylethyl pentanoate, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is low .