Phenethyl propionate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data is from peer reviewed journal and review article.

Justification for type of information:

Data is from peer reviewed journal and review article.

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

Biodegradation study was conducted for 30 days for evaluating the percentage biodegradability of test substance 2-phenylethyl propanoate.

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material (IUPAC name): 2-phenylethyl propanoate
- Common name: Phenethyl propionate (PEP)
- Molecular formula: C11H14O2
- Molecular weight: 178.2296 g/mol
- Smiles notation: c1(CCOC(=O)CC)ccccc1
- InChl: 1S/C11H14O2/c1-2-11(12)13-9-8-10-6-4-3-5-7-10/h3-7H,2,8-9H2,1H3
- Substance type: Organic
- Physical state: Liquid

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Pond water was collected from the Iowa State University Horticulture Farm pond (Ames, IA, USA).

Duration of test (contact time):

30 d

Initial conc.:

10 other: μg/g

Based on:

test mat.

Parameter followed for biodegradation estimation:

other: %degradation

Details on study design:

TEST CONDITIONS
- Solubilising agent (type and concentration if used): 300μl of acetone
- Test temperature: 25 ± 2°C
- pH:7.3
- Continuous darkness: yes/no: Yes
- Other: The alkalinity was 91 mg/ml, and the total hardness was 182 mg/ml.

TEST SYSTEM
- Culturing apparatus: French square bottles was used as a test vessel for the study.
- Number of culture flasks/concentration: There were four replications each for the dark group and the light group.
- Measuring equipment: HPLC method coupled with liquid scintillation counting (LSC).

SAMPLING
- Sampling frequency: Samples were taken at days 0, 0.25, 0.5, 1, 3, 7, 14, 21 and 30 post-treatment.

STATISTICAL METHODS: Dissipation rates of PEP were calculated using first-order open models. A student’s t-test was used to compare dissipation rates of PEP in light and in dark from the water dissipation studies.

Key result

Parameter:

other: %degradation

Value:

50

Sampling time:

5 d

Remarks on result:

other: Other details not known

Details on results:

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 retention time for test substance PEP was 5.4 min on the HPLC chromatogram.

Table: Dissipation half-lives (DT50) of PEP in water.

 

Incubation conditions	DT50 (days) (± S. D.)	R^2a	Replication (n)
PEP in water	5.2 (±0.07)	0.88	8

 

Where,

a = R²is the correlation coefficient for the first order dissipation model.

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

The percentage degradation of test 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 water.

Executive summary:

Biodegradation study was conducted for 30 days for evaluating the percentage biodegradability of test substance 2 -phenylethyl propanoate. 3H-phenethyl propionate were purchased from PerkinElmer Life Sciences and Analytical Sciences. (Boston, MA, USA). Analytical standards of phenethyl propionate, 2-phenylethanol, 2-(4-hydroxyphenyl) ethanol were purchased from Lancaster Synthesis, Inc. Methanol was purchased from Fisher Scientific Solvents used for extraction and chromatographic analysis were analytical reagent grade or better. Monophase® S scintillation cocktails were purchased from PerkinElmer Life and Analytical Sciences.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 in the pond water. 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” incubationsfrom 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’st-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 test substance2-phenylethyl propanoatewas determined to be 50% in 5 days.Thus, based on percentage degradation,2-phenylethyl propanoateis considered to be readily biodegradable in nature.

Description of key information

Biodegradation study was conducted for 30 days for evaluating the percentage biodegradability of test substance 2 -phenylethyl propanoate (Dingfue Hu and Joel Coats, 2008 & Dingfue Hu, 2007). 3H-phenethyl propionate were purchased from PerkinElmer Life Sciences and Analytical Sciences. (Boston, MA, USA). Analytical standards of phenethyl propionate, 2-phenylethanol, 2-(4-hydroxyphenyl) ethanol were purchased from Lancaster Synthesis, Inc. Methanol was purchased from Fisher Scientific Solvents used for extraction and chromatographic analysis were analytical reagent grade or better. Monophase® S scintillation cocktails were purchased from PerkinElmer Life and Analytical Sciences.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 in the pond water. 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” incubationsfrom 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 t-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 test substance2-phenylethyl propanoatewas determined to be50% in 5 days.Thus, based on percentage degradation,2-phenylethyl propanoateis considered to be readily biodegradable in nature.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Experimental study and predicted data for the target compound 2-phenylethyl propanoate (CAS No. 122-70-3) 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 (Dingfue Hu and Joel Coats, 2008) and review article (Dingfue Hu, 2007), biodegradation experiment was conducted for 30 days for evaluating the percentage biodegradability of test substance 2 -phenylethyl propanoate (CAS no. 122-70-3). 3H-phenethyl propionate were purchased from PerkinElmer Life Sciences and Analytical Sciences. (Boston, MA, USA). Analytical standards of phenethyl propionate, 2-phenylethanol, 2-(4-hydroxyphenyl) ethanol were purchased from Lancaster Synthesis, Inc. Methanol was purchased from Fisher Scientific Solvents used for extraction and chromatographic analysis were analytical reagent grade or better. Monophase® S scintillation cocktails were purchased from PerkinElmer Life and Analytical Sciences. 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 in the pond water. 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’st-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 test substance2-phenylethyl propanoate was determined to be50% in 5 days. Thus, based on percentage degradation,2-phenylethyl 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 compound2-phenylethyl propanoate(CAS No. 122-70-3) 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 2-phenylethyl propanoate is expected to be readily biodegradable.

 

For the read across chemical Benzyl Butyrate (CAS no. 103-37-7), the Ready Biodegradability of Benzyl Butyrate was determined by the Manometric respirometry(Study report Sustainability Support Service (Europe) AB with access rights from Givaudan-Regulatory Affairs and Product Safety, Company study no. 11-E225, 2011). The method used is basically the one described under No. 301 F in the OECD Guidelines for Testing of Chemicals. A measured volume of inoculated mineral medium, containing a known concentration of test substance 30 mg/L as the nominal sole source of organic carbon, is stirred in a closed flask at a constant temperature (± 1°C) for up to 28 days. Evolved carbon dioxide is absorbed in sodium hydroxide pellets. The consumption of oxygen is determined  by measuring  the pressure drop in the respirometer  flask. The Biological Oxygen Demand (BOD), amount of oxygen taken up by the microbial population during biodegradation of the test chemical (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of ThOD (Theoretical Oxygen Demand, calculated from the elemental composition, assuming that carbon is oxidized to carbon dioxide, hydrogen to water and nitrogen to ammonium, nitrite or nitrate). Benzyl Butyrate did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration. Benzyl Butyrate undergoes 88% biodegradation after 28 days (87%after 62 days) in the test conditions.The10-day window criterion is also fulfilled (20%biodegradation on day1 and 77% on day11). Thus, Benzyl Butyrate should be regarded as readily biodegradable according to this test.

 

Another biodegradation study for 28-days Manometric respirometry test following the OECD guideline 301F was conducted for determining the ready biodegradability of the read across chemical Benzyl butyrate (CAS No. 103-37-7) [UERLStudy Report, Sustainability Support Services (Europe) AB (Report no.103-37-7/01/2015/RBD), 2015]. % Degradation was calculated using the values of BOD and ThOD for test item and reference item. The BOD₂₈value of Benzyl butyrate (CAS No. 103-37-7) was observed to be 1.967 mgO₂/mg. ThOD was calculated as 2.424 mgO₂/mg. Accordingly, the % degradation of the read across item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 81.15%. Based on the results, chemical Benzyl butyrate, under the test conditions, was considered to be readily-Biodegradable at 20 ± 1°C over a period of 28 days.

In a supporting study from authoritative database (J-CHECK, HSDB, 2017 and Envichem, 2014) for the read across chemical 2-phenylethan-1-ol (CAS no. 60-12-8), biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance 2-phenylethan-1-ol.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 2-phenylethan-1-ol was determined to be 87, 95 and 100% by BOD, TOC removal and GC parameter in 14 days. Thus, based on percentage degradation, 2-phenylethan-1-ol is considered to be readily biodegradable in nature.

On the basis of above results for target chemical 2-phenylethyl propanoate (from peer reviewed journal and EPI suite, 2017) and for its read across substance (from study reports and authoritative database J-CHECK, HSDB, 2017 and Envichem, 2014), it can be concluded that the test substance 2-phenylethyl propanoate can be expected to be readily biodegradable in nature.