Diphenylacetic acid

Endpoint summary

Description of key information

Short-term toxicity to fish

Fish Acute Toxicity test according to OECD Guideline 203 was conducted for (test item name) diphenyl acetic acid The nominal concentration selected for the experiment were 100mg/Land test fish were exposed to these concentration for 96 hours. The lethal concentrations LC50 was found to be >100 mg/L

No mortality was observed at 100 mg/l in 96 hrs exposure period thus LC0 was considering to be 100 mg/l.

Short term toxicity to aquatic invertebrates

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, the short term toxicity on aquatic invertebrates was predicted fordiphenylacetic acid (CAS No.117-34-0). EC50 value was estimated to be 74.33 mg/L on the basis of intoxication for Daphnia magna for 48 hrs duration.

Based on this value it can be concluded that the diphenylacetic acid (CAS No.117-34-0) was considered to be toxic to aquatic invertebrates and can be considered to be classified in aquatic chronic 3 as per the CLP regulations.

Toxicity to aquatic algae and cyanobacteria

The effect of test item diphenyl acetic acid, CAS No. 117-34-0 was studied on the growth of fresh water green alga Chlorella vulgaris (UERL study report, Sustainability Support Services (Europe) AB, 2017). The study was conducted following OECD guideline 201 - Alga, growth inhibition test. The test concentration chosen for the study were 6.25 mg/L,12.5 mg/L,25 mg/L,50 mg/L,100 mg/L,200 mg/L. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be >200 mg/L. Thus based on this value, it can be concluded that the substance diphenyl acetic acid can be considered as non-toxic to aquatic organisms and thus cannot be classified as hazardous as per the CLP classification criteria.

Toxicity to microorganisms

The toxicity to micro organism of the substance 1,1-Diphenylacetic acid (Cas no. 117-34-0) to micro organism Tetrahymena pyriformis is predicted using QSAR toolbox version.3.3, based on the effects observed in a static freshwater system during a 48 hr exposure. The Inhibition growth concentration (IGC50) for the substance 1,1-Diphenylacetic acid is estimated to be 187.29 mg/L. Based on this value, it can be concluded that the test chemical 1,1-Diphenylacetic acid (Cas no. 117-34-0) may have no concern to micro organism toxicity for acute exposure period.

Additional information

Short-term toxicity to fish

Three studies including those from experimental study and validated prediction for short term fish toxicity endpoint of target chemical 1,1-Diphenylacetic acid (Cas no. 117-34-0) were summarized as followed: 

 

First experimental key study by UERL laboratory; 2017 suggest the Fish Acute Toxicity test according to OECD Guideline 203 was conducted for 1,1-Diphenylacetic acid, The nominal concentration selected for the experiment were 100 mg/Land test fish were exposed to these concentration for 96 hours. The lethal concentrations LC50 was found to be >100 mg/L. No mortality was observed at 100 mg/l in 96 hrs exposure period thus LC0 was considering to be 100 mg/l.

 

Above aquatic classification supported by peer review journal (Spec.Sci.Rep.Fish.No.207, Fish Wildl.Serv., U.S.D.I., Washington, DC:157 p., 1957)which indicate the short term toxicity study to Lepomis macrochirus (Bluegill),Oncorhynchus mykiss (Rainbow  trout) and Petromyzon marinus (Sea Lamprey) was carried out for 24 hrs. Test was performed under static conditions. After exposure to test animal at dose conc.5 mg/l of test chemical 1,1-Diphenylacetic acid, no mortality effects were observed on fish. Thus, the NOEC value was consider to be 5 mg/l respectively.

 

Last study is prediction for target from EPI Suite ECOSAR version 1.10 model which indicate the 96 hours LC50 was estimated to be 193.66 mg/l on Fish using neutral organics class for prediction. Based on this value, it can be concluded that the test chemical 1,1-Diphenylacetic acid can be considered as non toxic to fish at mentioned predicted lethal concentration thus it can be considered not classified as per the CLP classification criteria.

Thus all available studies for target gives the lethal concentration is in the range of 100-193.66 mg/l and NOEC was 5 mg/l concluded that the test chemical 1,1-Diphenylacetic acid (Cas no. 117-34-0) considered as non-toxic to fish and thus cannot be classified as hazardous as per the CLP criteria.

Short term toxicity to aquatic invertebrates

Short term toxicity to aquatic invertebrates by diphenylacetic acid (CAS No.117-34-0) was summaries with one prediction data for target and two experimental studies of read across which are functionally similar are as follows:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, the short term toxicity on aquatic invertebrates was predicted fordiphenylacetic acid (CAS No.117-34-0). EC50 value was estimated to be74.33mg/L on the basis of intoxication for Daphnia magna for 48 hrs duration.

 

A study on read across 5-(2, 5-dimethylphenoxy)-2, 2-dimethylpentanoic acid (25812-30-0) from Ecotox database 2016, for short term toxicity to aquatic invertebrates was performed in 5 Daphnia. Concentrations ranges from 17.01-28.69 mg/l. They were treated for 48 hrs. After 48 hrs, the EC 50 value for 5-(2, 5-dimethylphenoxy)-2, 2-dimethylpentanoic acid (25812-30-0) for daphnia magna was determined to be 22.85 mg/l on the basis of intoxication.

 

For the same read across and from same Ecotox database another test was performed in 5 Daphnia.

Concentrations range from 42.2-72.3 mg/l. They were treated for 48 hrs. After the 48 hrs, the EC 50 value for 5-(2, 5-dimethylphenoxy)-2, 2-dimethylpentanoic acid (25812-30-0) for daphnia magna was determined to be 56.5 mg/l on the basis of intoxication.

 

As based on the above prediction for target chemical and experimental studies for read across 5-(2, 5-dimethylphenoxy)-2, 2-dimethylpentanoic acid (25812-30-0), all result values were come under the aquatic chronic 3 category. Thus based on that, diphenylacetic acid (CAS No.117-34-0) was considered to be toxic to aquatic invertebrates and can be classified in aquatic chronic 3 categories as per the CLP regulations.

Toxicity to aquatic algae and cyanobacteria

Experimental key study for the target chemical Diphenylacetic acid (CAS no. 117-34-0) which is supported further by total 2 studies (both from peer reviewed journal) for its closest structurally similar read across substance with logKow as the primary descriptor were reviewed for the toxicity to aquatic algae and cyanobacteria end point which are summarized as below:

 

In an experimental key study, the effect of test item diphenyl acetic acid, CAS No. 117-34-0 was studied on the growth of fresh water green alga Chlorella vulgaris (UERL study report, Sustainability Support Services (Europe) AB, 2017). The study was conducted following OECD guideline 201 - Alga, growth inhibition test. The test concentration chosen for the study were 6.25 mg/L,12.5 mg/L,25 mg/L,50 mg/L,100 mg/L,200 mg/L. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be >200 mg/L. Thus based on this value, it can be concluded that the substance diphenyl acetic acid can be considered as non-toxic to aquatic organisms and thus cannot be classified as hazardous as per the CLP classification criteria.

 

In a supporting study of read across substanceBenzoic acid (CAS no. 65-85-0) from peer reviewed journal (GLENN W. STRATTON & CHARLES T. CORKE, 1982), short term toxicity study was carried out using cyanobacteria (blue-green algae) Anabaena inaequalis, A. cylindrica, and A.variabilis, and the green algae Chlorella pyrenoidosa and Scenedesmus quadricauda as a test organism. The study was based on the effects of the test compound Benzoic acid on algae in a static fresh water system. Stock solutions of test chemical were prepared in pesticide grade acetone. The proper level of acetone (0.1 %v/v) to use in each bioassay system was determined using the solvent-pesticide interaction analysis technique. Chemical was tested at a minimum of five concentrations ranging from 0 to 100 mg/l (nominal concentration). Test organisms used for the study include (blue-green algae) Anabaena inaequalis, A. cylindrica, and A.variabilis, and the green algae Chlorella pyrenoidosa and Scenedesmus quadricauda, respectively.

Cultures of Anabaena inaequalis and A. cylindrica were maintained in a liquid nitrogen-free medium at a temperature of 20°C and a light intensity of 7000 lux on a 12 h light-dark cycle whereas the other cultures such as A.variabilis, Chlorella pyrenoidosa and Scenedesmus quadricauda were maintained under the same conditions except the growth medium was supplemented with 1.5 g NaNO3/l. Photosynthesis was assayed by following the uptake of 14CO2 from NaH14CO3 (Amersham/Searle, Oakville, Ontario, Canada). Plastic tissue culture flasks with a total internal volume of 74 ml were employed as assay chambers. Each contained 9.9ml of cell suspension (containing 6-5 × 10(4)cyanobacteria or 1.0 × 10(5)green algal cells/ml), 0.1 ml of radioisotope (to give a final activity of 0.1µCi/ml) and 0.01 ml of test chemical. The flasks were incubated for 3 h and photosynthetic activity was assayed. Per cent inhibition values were calculated relative to photosynthetic activity in control systems (solvent only) and EC50 values determined by probit or regression analysis, where applicable. Analyses for significant differences (p = 0.05) were performed using Dunnett's testand Duncan's multiple range test. Based on the effect of Benzoic acid on the photosynthesis of the test organisms, the EC50 value was determined to be 5, 60, 55, 60 and 75 mg/l for Anabaena inaequalis, A. cylindrical, A.variabilis, Chlorella pyrenoidosa and Scenedesmus quadricauda respectively. Thus, based on this value, it can be concluded that the test chemical Benzoic acid can be considered as toxic to aquatic organisms. Since the test chemical is readily biodegradable in nature, chemical Benzoic acid can be considered as non-toxic to aquatic organisms and thus can be considered as not classified as per the CLP classification criteria

 

Another supporting study of the same read across substance Benzoic acid (CAS no. 65-85-0) on Pseudokirchneriella subcapitata in a static fresh water system was carried out for 48 hrs. The study was performed according to closed system algal toxicity test. Algal inoculum was withdrawn from the chemostat operated under a steady state, and transferred into 300mL BOD bottles, together with dilution water (with growth medium) and toxicants. The BOD bottles were filled completely, leaving no headspace. A water seal was provided to ensure a closed test environment. The bottles were then placed on an orbital shaker operated at 100 rpm. Temperature and light intensity were kept at 24±1◦C and 65 µEm2/s (± 10%), respectively. The final yield and algal growth rate based on cell density counts was determined. The population density of the algae was determined using an electronic particle counter. Probit analysis was applied to determine the concentration– response relationship and the median effective concentration (EC50). One-tail Dunnett’s procedure was applied for the estimation of NOEC and LOEC values at 5% level of significance. On the basis effect on growth rate and yield of the test organism Pseudokirchneriella subcapitata (green algae), the 48 hr EC50 value was determined to be 83.29 and 36.39 mg/l, respectively and the NOEC value was determined to be 4.81 and 9.62 mg/l, respectively. Thus, based on this value, it can be concluded that the test chemical Benzoic acid can be considered as toxic to aquatic organisms. Since the test chemical is readily biodegradable in nature, chemical Benzoic acid can be considered as non-toxic to aquatic organisms and thus can be considered as not classified as per the CLP classification criteria

 

Thus, based on the overall reported results for target chemical Diphenylacetic acid (UERL study report, 2017) and for its read across substance (from peer reviewed journal), it can be concluded that the test substance Diphenylacetic acid can be considered as non-toxic to aquatic organisms at environmentally relevant concentrations and can be considered to be not classified as per the CLP classification criteria.

 

 

Toxicity to microorganisms

Three studies which includes reliable predicted data and experimental results from authorative database for micro organism toxicity of test chemical 1, 1-Diphenylacetic acid (Cas no. 117-34-0) with relevant read across which is close to target using log Kow as primary descriptor were summarized as follows:

 

First prediction done using QSAR toolbox version.3.3 which indicate the toxicity to micro organism of the substance 1, 1-Diphenylacetic acid (Cas no. 117-34-0) to micro organism Tetrahymena pyriformis is predicted based on the effects observed in a static freshwater system during a 48 hr exposure. The Inhibition growth concentration (IGC50) for the substance 1, 1-Diphenylacetic acid is estimated to be 187.29 mg/L. Based on this value, it can be concluded that the test chemical 1, 1-Diphenylacetic acid (Cas no. 117-34-0) may have no concern to micro organism toxicity for acute exposure period.

 

Above result assist by experimental data of read across 4-Methylbenzoic acid (Cas no. 99-94-5) suggest Inhibition concentration to 50% of test organisms (IGC50) for the substance 4-Methylbenzoic acid (CAS no. 99-94-5) was determine to be 213.42 mg/l on micro organism species Tetrahymena pyriformis (Ciliate) on the basis of effect on Population growth rate in static fresh water..(ECOTOX DATABASE; 2017)

 

And another read across chemical Nicotinic acid (Cas no. 59-67-6) from same data source i.e ECOTOX database; 2017 indicate Inhibition concentration to 50% of test organisms (IGC50) for the substance Nicotinic acid (Cas no. 59-67-6) was determine to be 2792.91 mg/l on micro organism species Tetrahymena pyriformis (Ciliate) on the basis of effect on Population growth rate in static fresh water.

All available studies give the Inhibition concentration to 50% of test organisms (IGC50) is in the range of 187.29 -2792.91 mg/l which indicate the test chemical 1, 1-Diphenylacetic acid (Cas no. 117-34-0) may have no concern to micro organism toxicity for acute exposure period.