Phenethyl benzoate

Endpoint summary

Description of key information

Biodegradation in water

The target test substance was investigated for its readily biodegradibilty nature by following OECD 301D guidelines. The test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. The activated sludge was collected from SMS Municipal sewage treatment plant (130 MLD STP) in a thoroughly cleansed container. The sampling site for collection of the activated sludge was selected ensuring that no known history of its contamination with the test item within the previous four years considering the history of possible agricultural, industrial or domestic inputs. The sampling depth was 1-2 feet from the aeration tank. The temperature of the activated sludge was measured (38ºC) at the site of collection. Oxygen concentration of the activated sludge sample was 2.9 mg/L. The sample was transported to the test facility within 3 hours from collection and kept it aerobic during transport. Sludge was pre-conditioned by decanting the supernatant of the activated sludge and later washed with sludge by mineral media followed by aerating for 1 day at the 20º Ctest temperature. Aliquot of the final sludge suspension weighed, dried and the ratio of wet sludge to its dry weight determined and concentration of sludge was 0.96 g dry material per litre final test medium. The biodegradation was determined by following the BOD, oxygen consumption of the test item in the incubation vessels during exposure. Sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.125 mL glass vessels (beakers) were used in the study. The test system includes an inoculum blank control group, a procedure control group, and a test item group a toxicitycontrol group, each maintained in replicates. All test vessels were incubated at BOD incubator at a constant temperature of 20°C. Sampling of all test vessels from each test group concentration were collected for analysis at zero-time (immediately after set-up), 3h, 7th, 14th, 21st, 28th, 35 th and 42nd day during the incubation period. Samples were removed at regular intervals, which were measured for BOD. The theoretical oxygen demand (THOD) was calculated based on the chemical identifier. The procedure control Sodium benzoate was sufficiently degraded to 65.87 % after 14 days, and to 74.85 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the procedure control sodium benzoate, 32.28% biodegradation was noted within 14 days and 48.58% biodegradation was determined after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory to the activated sludge microorganisms. Under the test conditions the mean percentage biodegradation of test chemical reached 44.53% after 28 days of incubation based on Oxygen consumption. As the final biodegradation is less than 70% in this test and all validity criteria were met, test chemical can be considered to be potentially inherently biodegradable

Biodegradation in water and sediment

Estimation Programs Interface suite prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 21.9% 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 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 in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 5% (i.e, reported as 3.09%), indicates that test chemical is not persistent in sediment.

Biodegradation in soil

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database. If released into the environment, 73.4 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical, it is concluded that the test 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

Experiment study of the test chemical and various supporting weight of evidence studies for its structurally and functionally similar read across chemicals were reviewed for the biodegradation in water end point which are summarized as below:

The target test substance was investigated for its readily biodegradibilty nature by following OECD 301D guidelines. The test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. The activated sludge was collected from SMS Municipal sewage treatment plant (130 MLD STP) in a thoroughly cleansed container. The sampling site for collection of the activated sludge was selected ensuring that no known history of its contamination with the test item within the previous four years considering the history of possible agricultural, industrial or domestic inputs. The sampling depth was 1-2 feet from the aeration tank. The temperature of the activated sludge was measured (38ºC) at the site of collection. Oxygen concentration of the activated sludge sample was 2.9 mg/L. The sample was transported to the test facility within 3 hours from collection and kept it aerobic during transport. Sludge was pre-conditioned by decanting the supernatant of the activated sludge and later washed with sludge by mineral media followed by aerating for 1 day at the 20º Ctest temperature. Aliquot of the final sludge suspension weighed, dried and the ratio of wet sludge to its dry weight determined and concentration of sludge was 0.96 g dry material per litre final test medium. The biodegradation was determined by following the BOD, oxygen consumption of the test item in the incubation vessels during exposure. Sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.125 mL glass vessels (beakers) were used in the study. The test system includes an inoculum blank control group, a procedure control group, and a test item group a toxicitycontrol group, each maintained in replicates. All test vessels were incubated at BOD incubator at a constant temperature of 20°C. Sampling of all test vessels from each test group concentration were collected for analysis at zero-time (immediately after set-up), 3h, 7th, 14th, 21st, 28th, 35 th and 42nd day during the incubation period. Samples were removed at regular intervals, which were measured for BOD. The theoretical oxygen demand (THOD) was calculated based on the chemical identifier. The procedure control Sodium benzoate was sufficiently degraded to 65.87 % after 14 days, and to 74.85 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the procedure control sodium benzoate, 32.28% biodegradation was noted within 14 days and 48.58% biodegradation was determined after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory to the activated sludge microorganisms. Under the test conditions the mean percentage biodegradation of test chemical reached 44.53% after 28 days of incubation based on Oxygen consumption. As the final biodegradation is less than 70% in this test and all validity criteria were met, test chemical can be considered to be potentially inherently biodegradable

 

In an experimental key study from study report (2018), biodegradation study was conducted for 35-days following the OECD guideline 301 D for determining the ready biodegradability of the test chemical. The study was performed at a temperature of 20°C under aerobic conditions. Aerobic conditions was provided by means of mineral media which is aerated for 20 hours prior to start of the experiment. The test system included control, test chemical and reference substance. Polyseed capsule (mixed culture) was used as a test inoculum for the study. Test inoculum polyseed capsule was composed of blend of specialized microbial cultures and food grade gelatin made by International Laboratory Supply (InterLab), LTD. No pretreatment / preconditioning was given to the test inoculum as the polyseed capsule requires only one hour of stirring to activate it. 1 Polyseed capsule was added in 500 mL DI water and then stirred for 1 hour for proper mixing and functioning of inoculum & settled for 15 minutes to eliminate the bran. Decanted polyseed solution was used as mixed inoculum. Thus, concentration of test inoculum used for the study was 32 ml/l which corresponds to 10E7 to 10E8 CFU/ml. The concentration of test and reference substance (Sodium Benzoate) chosen for both the study was 4 mg/L. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference chemical was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test chemical and reference substance. The % degradation of procedure control (reference substance) was also calculated using BOD & ThOD and was determined to be 73.49 %. Degradation of Sodium Benzoate exceeds 39.15 % on 7 days & 70.48 % on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD35 value of test chemical was observed to be 1.17 mgO2/mg. ThOD was calculated as 2.47 mgO2/mg. Accordingly, the % degradation of the test chemical after 35 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 47.36 %. Based on the results, the test chemical under the test conditions, was considered to be inherently biodegradable in nature.

 

Another biodegradation study was conducted for 28-days in accordance with the OECD guideline 301 D for determining the ready biodegradability of the test chemical (Study report, 2018). The study was performed at a temperature of 20°C under aerobic conditions and using the same procedure alongwith the test conditions as mentioned in the above study. The concentration of test and reference substance (Sodium Benzoate) chosen for both the study was 4 mg/L. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference chemical was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test chemical and reference substance. The % degradation of procedure control (reference substance) was also calculated using BOD & ThOD and was determined to be 79.51%. Degradation of Sodium Benzoate exceeds 64.46% on 7 days & 75.30% on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.22 mgO2/mg. ThOD was calculated as 2.47 mgO2/mg. Accordingly, the % degradation of the test chemical after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 49.39%. Based on the results, the test chemical under the test conditions, was considered to be inherently biodegradable in nature.

 

In a supporting weight of evidence study from peer reviewed journal (A.M. Api et. al., 2016), Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test chemical. The study was performed in accordance with the OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test) under aerobic conditions. The percentage degradation of test chemical was determined to be 49% in 28 days. Thus, based on percentage degradation, test chemical was considered to be inherently biodegradable in water.

 

On the basis of above results of the test chemical, it can be concluded that the test chemical was considered to be inherently biodegradable in water.

Biodegradation in water and sediment

Estimation Programs Interface suite prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 21.9% 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 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 in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 5% (i.e, reported as 3.09%), indicates that test chemical is not persistent in sediment.

Biodegradation in soil

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database. If released into the environment, 73.4 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical, it is concluded that the test 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 chemical was considered to be inherently biodegradable in water.