Diphenylacetic acid

Endpoint summary

Description of key information

Biodegradation in water

Biodegradation study was conducted for 30 days for evaluating the percentage biodegradability of test substance Diphenylacetic acid (by R. V. Subba-Rao and Martin Alexander, 1977). Bacteria was used as an inoculum.Microbial inoculum was isolated from Hudson Collamer silt loam. The test was performed under aerobic conditions at a temperature of 25ᵒC, respectively.The chemicals were introduced into the BOD bottles as sole carbon sources at a concentration of 2 mg of carbonper bottle. The compounds were added in acetone solutions,and the acetone was evaporated prior to the additionof 02 -saturated water. Each bottle received 5 mgof Hudson Collamer silt loamasa source of the microbial inoculum. The bottles were filled with the air-saturated salts solution and closed with glass stoppers. Bottles containing O2 saturated water inoculated with soil (as a source of microbial inoculum) but no carbon source were also included in the study to account for the O2 depletion resulting from microbial oxidation of organic matter and ammonium. Test compound was also tested in combination with glucose (both at a conc. of 2 mg of carbon per bottle) to test whether the possible lack of biodegradation was a result of toxicity of the test chemical. DissolvedO2in the bottles was measured at regular intervals using a Yellow Spring Instrument Co. oxygen analyzer, Model 53.The instrument was calibrated with the salts solution, the O2 content of which was determined by the Alsterberg modification of the Winkler method. At regular intervals, the dissolved O2 in the samples was measured after calibrating the instrument with a BOD bottle containing inoculated 02 -saturated water supplemented with 0.1% KCN. The solutions in bottles showing O2 depletion were used to obtain microorganisms capable of utilizing the substrate. Test chemical diphenyl acetic acid was not found to be decomposed appreciable in BOD bottles, indicating that the chemical is not 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 Diphenylacetic acid (CAS No. 117 -34 -0). If released in to the environment, 16.5% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of Diphenylacetic acid 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 Diphenylacetic acid 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 0.625%), indicates that Diphenylacetic acid is not persistent in sediment.

Biodegradation in soil

The half-life period of Diphenylacetic acid (CAS No. 117 -34 -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, 82.8% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of Diphenylacetic acid in soil is estimated to be 30 days (720 hrs). Based on this half-life value of Diphenylacetic acid, 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

From BCFBAF (v3.00) model of EPI suite and PBT profiler the estimated bio concentration factor (BCF) for 1,1-Diphenylacetic acid is 3.2 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000.Thus it is concluded that 1,1-Diphenylacetic acid is not expected to bio accumulate in the aquatic environment.

Adsorption / desorption

The adsorption coefficient Koc in soil and in sewage sludge diphenyl acetic acid(CAS No.117-34-0) was determined by the Reverse Phase High Performance Liquid Chromatography method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to functional group similarity with the test substance and calibration graph prepared. The reference substances were xylene,ethylbenzene, toluene, naphthalene and phenanthrene having Koc value ranging from 2.369 to 4.09. The Log Koc value was found to be 0.6316 ± 0.0131 at 25°C.

Additional information

Biodegradation in water

1 experimental key study and 2 supporting predicted data for the target compound Diphenylacetic acid (CAS no. 117-34-0) alongwith the total 2 supporting studies (from authoritative database) for its closest structurally similar read across substance with logKow as the primary descriptor were reviewed for the biodegradation end point which are summarized as below:

 

In a key study frompeer reviewed journal(by R. V. Subba-Rao and Martin Alexander, 1977) for target chemicalDiphenylacetic acid(CAS no. 117-34-0), biodegradation experiment was conducted for 30 days for evaluating the percentage biodegradability of test substance Diphenylacetic acid. Bacteria was used as an inoculum. Microbial inoculum was isolated from Hudson Collamer silt loam. The test was performed under aerobic conditions at a temperature of 25ᵒC, respectively. The chemicals were introduced into the BOD bottles as sole carbon sources at a concentration of 2 mg of carbon per bottle. The compounds were added in acetone solutions, and the acetone was evaporated prior to the addition of 02 -saturated water. Each bottle received 5 mg of Hudson Collamer silt loam as a source of the microbial inoculum. The bottles were filled with the air-saturated salts solution and closed with glass stoppers. Bottles containing O2 saturated water inoculated with soil (as a source of microbial inoculum) but no carbon source were also included in the study to account for the O2 depletion resulting from microbial oxidation of organic matter and ammonium. Test compound was also tested in combination with glucose (both at a conc. of 2 mg of carbon per bottle) to test whether the possible lack of biodegradation was a result of toxicity of the test chemical. DissolvedO2in the bottles was measured at regular intervals using a Yellow Spring Instrument Co. oxygen analyzer, Model 53.The instrument was calibrated with the salts solution, the O2 content of which was determined by the Alsterberg modification of the Winkler method. At regular intervals, the dissolved O2 in the samples was measured after calibrating the instrument with a BOD bottle containing inoculated 02 -saturated water supplemented with 0.1% KCN. The solutions in bottles showing O2 depletion were used to obtain microorganisms capable of utilizing the substrate. Test chemical diphenyl acetic acid was not found to be decomposed appreciable in BOD bottles, indicating that the chemical is not readily biodegradable in nature.

 

In a predicted data done by using QSAR toolbox version 3.3 with logKow as the primary descriptor (2017), percentage biodegradability of test chemicalDiphenylacetic acid(CAS no. 117-34-0)was estimated. Test substance undergoes 45.11% degradation by CO2 evolution parameter in 28 days. Thus, based on percentage degradation, the test chemical Diphenylacetic acid was estimated to be not readily biodegradable in water.

 

In another prediction done by using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compoundDiphenylacetic acid(CAS no. 117-34-0) 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 Diphenylacetic acid is expected to be not readily biodegradable.

 

Another supporting study of biodegradation was conducted for 24 hrs for evaluating the percentage biodegradability of read across substance L-Tyrptophan (CAS no. 73 -22 -3) (HSDB, 2016). The study was performed in a Warburg respirometer for a period of 24 hrs. Initial substance concentration used for the study was 500 mg/l and activated sludge was used as a test inoculum. The percentage degradation of read across substance was determined to be 0.6, 1.4 and 4.6% by BOD parameter in 6, 12 and 24 hrs, respectively. Thus, based on percentage degradation, L-Tyrptophan is considered to be not readily biodegradable in nature.

 

In an additional supporting dataof read across4-tert-Butylbenzoic acid (CAS no. 98 -73 -7) from authoritative database (J-CHECK, 2016), biodegradation experiment was carried out for 28 days for evaluating the percentage biodegradability of read across substance 4-tert-Butylbenzoic acid. 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 test substance formed Pivalic acid at the point showing the degradation tendency in (Sludge + Test Substance) system. Percentage degradation of test substance was determined to be 4 and 13% by BOD and HPLC parameter in 28 days. Thus, based on percentage degradation, 4 -tert-Butylbenzoic acid is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemicalDiphenylacetic acid(from peer reviewed journal, OECD QSAR toolbox version 3.3 and EPI Suite) and for its read across substance (from authoritative database HSDB and J-CHECK), it can be concluded that the test substanceDiphenylacetic acidcan be expected to be not 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 Diphenylacetic acid (CAS No. 117 -34 -0). If released in to the environment, 16.5% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of Diphenylacetic acid 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 Diphenylacetic acid 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 0.625%), indicates that Diphenylacetic acid is not persistent in sediment.

Biodegradation in soil

The half-life period of Diphenylacetic acid (CAS No. 117 -34 -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, 82.8% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of Diphenylacetic acid in soil is estimated to be 30 days (720 hrs). Based on this half-life value of Diphenylacetic acid, 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 substanceDiphenylacetic acid can be considered to be not readily biodegradable in nature.

Bioaccumulation: aquatic / sediment

Four studies including predicted data from validated models and experimental data from authorative database for bioaccumulation (BCF) endpoint of target chemical 1,1-Diphenylacetic acid (Cas no. 117-34-0) with relevant read across which is structurally similar to target were summarized as follows: 

 

First study from prediction done using BCFBAF (v3.00) model and PBT profiler which indicate the estimated bio concentration factor (BCF) for 1,1-Diphenylacetic acid is 3.2 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000.Thus it is concluded that 1,1-Diphenylacetic acid is not expected to bio accumulate in the aquatic environment.

 

Above prediction is supported by data Scifinder database which suggest the Bioconcentration factor (BCF) for target chemical 1,1-Diphenylacetic acid was predicted to be 66.9 at pH 1, 66.8 at pH 2, 65.7 at pH 3, 56.2 at pH 4, 23.0 at pH 5, 3.35 at pH 6, 1.0 at pH range 7-10 and temperature 25 deg.C.Based on the BCF concentration at all range of pH it is concluded that the test chemical 1,1-Diphenylacetic acid is non bioaccumulative in nature as it does not exceed the BCF criteria of 2000. 

Another estimation from Chemspider - ACD/PhysChem Suite indicate the Bioconcentration factor (BCF) for target chemical 1,1-Diphenylacetic acid was estimated to be 33.76 at pH 5.5 and 1.00 at pH 7.4 at temperature 25 deg.C.Based on the BCF concentration at two different pH concluded that the test chemical 1,1-Diphenylacetic acid is non bioaccumulative in nature as it does not exceed the BCF criteria of 2000. 

Above all results for target are further supported by experimental data of read across chemical nicotinic acid (Cas no. 59-67-6) which suggest an estimated BCF value of 3 was calculated in fish for nicotinic acid, using a log Kow of 0.36 and a recommended regression derived equation. This BCF value suggests that the potential for bioconcentration in aquatic organisms (fish) is low. (HSDB database by US EPA; 2017)

Thus based on all available studies for bioaccumulation endpoint concluded that the test substance 1,1-Diphenylacetic acid (Cas no. 117-34-0) is expected to be non Bioaccumulative in aquatic environment.

Adsorption / desorption

Two studies including experimental study and predicted data from validated model for adsorption (KOC) endpoint of target chemical 1,1-Diphenylacetic acid (Cas no. 117-34-0) were summarized as follows:

 

First study from experimental report by UERL laboratory; 2017 which suggest the adsorption coefficient Koc in soil and in sewage sludge diphenyl acetic acid(CAS No.117-34-0) was determined by the Reverse Phase High Performance Liquid Chromatography method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to functional group similarity with the test substance and calibration graph prepared. The reference substances were xylene,ethylbenzene, toluene, naphthalene and phenanthrene having Koc value ranging from 2.369 to 4.09. The Log Koc value was found to be 0.6316 ± 0.0131 at 25°C.

Above result supported by predicted model Chemspider - ACD/PhysChem Suite, indicate the soil adsorption coefficient i.e Koc value of test substance 1,1-Diphenylacetic acid was estimated to be 3.94 (log koc: 0.59) at pH 7.4 and  temp.25 deg.C Koc values at mentioned pH indicates that the substance 1,1-Diphenylacetic acid has negligible sorption to soil and sediment and therefore have rapid migration potential to groundwater.

Thus both studies for adsorption endpoint gives the common conclusion that the test substance 1,1-Diphenylacetic acid (Cas no. 117-34-0) is expected to have high mobility in soil and sediment compartment.