Methyl 2-naphthyl ether

Endpoint summary

Description of key information

Short term toxicity to fish

The objective of this study is to assess the Acute Toxicity of test chemical in Freshwater Fish (Danio rerio).The study was performed in compliance with OECD 203 Guideline for the testing of chemicals; Fish, Acute Toxicity Testing, (18th June, 2019). Solubility of the test item was performed by weighing 25.2 mg of test item in a glass vial and dissolved in 75 µL of acetone and transferred into the 1000 ml measuring cylinder, and made up to the 750 ml using natural water and the resulting concentration is 33.36 mg/L. Stability of the test item in natural water determined by analyzing the test concentrations of 1 and 30 mg/L at 0 hour, 24 hour, 48 hour, 72 hour and 96 hour showed that the test item concentration remained 80% to 120% (between97.83% and 99.27% for 1 mg/L and between97.45% and 99.24% for 30 mg/L) with respect to initial measured concentration and hence the dose verification for definitive test was performed at the beginning and at the termination of the test. Range finding test was conducted with test concentration of 2.80, 5.04, 9.07, 16.33 and 29.39 mg/L along with a control groups without test item by static method. Each concentration contained seven fish. Test item was first formulated in acetone (not exceeding 0.1 ml /L) follwed by natural water. No mortality (percent) observed in control groups and in the tested concentrations of 2.80, 5.04 and 9.07 mg/L whereas, 14.29% and 100% in 16.33 and 29.39 mg/L for a period of 96 hours. No clinical sign observed in control groups and in all the tested concentrations for a period of 96 hours. Based on the results of range finding test, the definitive test was conducted with test concentrations of 10.0, 13.0, 16.9, 22.0 and 28.6 mg/L along with a control groups without test item by static method. Each concentration contained seven fish. Test item was formulated in (not exceeding 0.1 ml /L) follwed by natural water. No mortality (Cumulative mortality percent) observed in control groups and in the tested concentration of 10.0 mg/L and 13.0 mg/L whereas, 42.86%, 57.14%, and 85.71% in 16.9, 22.0 and 28.6 mg/L for a period of 96 hours. No clinical signs observed in control groups and in the tested concentration of 10.0 mg/L whereas, Loss of equilibrium (Loss of buoyancy control) in 16.9, 22.0 and 28.6 mg/L, Abnormal Swimming behaviour (Corkscrew swimming) in 13.0, 16.9, 22.0 and 28.6 mg/L for a period of 96 hours. The test item available in the test medium (natural water) was determined by a validated HPLC method. The test item concentration oftest itemin the test medium at the initiation (0 hour) and 96 hours was 94.79% to 96.23 % for 10.0 mg/L, 94.08 % to 95.02 % for 16.9 mg/L, 95.07% to 95.56 % for 28.6 mg/L % of the nominal test concentrations. As the measured concentrations were within 80 to 120% of the nominal concentration during the definitive test period. Based on the results of the study, the test item,2-methoxynaphthaleneLC₅₀value at 96 hours was found to be 20.18 mg/Lwith 95% confidence limits between19.32 mg/Land21.04 mg/l. Based on the 96 hours LC50 value the test chemical can be categorised in chronic category 3 as per CLP classification criteria.

 

Long term toxicity to fish

Based on the prediction done using ECOSAR version 1.11, the long term toxicity on fish was predicted for test chemical (2017). On the basis of effects observed in a flow through freshwater system on test organism, the NOEC value for the substance was estimated to be 1.09 mg/l for fish for 28 days of exposure duration. Thus, it can be concluded that the test chemical can be considered as non-toxic to fish at environmentally relevant concentrations.

 

Short term toxicity to aquatic invertebrates

The overall study concludes that target test chemical is toxic to aquatic environment with EC50 value after 48 hours exposure ranging from 4.04 to 52 mg/L.

 

Long term toxicity to aquatic invertebrates

The study outlines the adverse effects of test chemical on reproduction of Daphnia magna, the test was conducted following the OECD guidelines 211 (Experimental study report, 2018). A semi static regime was followed in which the test chemical was renewed at every alternate day till 21 days of study. Nominal concentrations were used i.e., from of 0.625 mg/L, 1.25 mg/L, 2.5 mg/L, 5 mg/L and 10 mg/L, and reproduction effect was studied for 21 days based on the number of off springs produced. All the validity criteria were fulfilled per OECD guidelines. The median effective concentration (EC50) and effective concentration at 10% inhibition was determined as 5.89±1.76 and 1.20± 0.6 mg/L, respectively. Thus, it can be concluded that the test chemical can be considered as non-toxic to aquatic invertebrate at environmentally relevant concentrations.

 

Toxicity to aquatic algae and cyanobacteria

On the basis of the experimental studies of the functionally similar read across chemical and applying the weight of evidence approach, the 72/96 hr EC50 value (ErC50) of the test chemical on test organism green algae was determined to be in the range 4.93 to 9.571 mg/l, respectively.

 

Toxicity to microorganisms

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach, the EC50 value of the test chemical on test organism can be expected to be ranges from 13.5 to 19 mg/l.

Additional information

Short term toxicity to fish

The objective of this study is to assess the Acute Toxicity of test chemical in Freshwater Fish (Danio rerio).The study was performed in compliance with OECD 203 Guideline for the testing of chemicals; Fish, Acute Toxicity Testing, (18th June, 2019). Solubility of the test item was performed by weighing 25.2 mg of test item in a glass vial and dissolved in 75 µL of acetone and transferred into the 1000 ml measuring cylinder, and made up to the 750 ml using natural water and the resulting concentration is 33.36 mg/L. Stability of the test item in natural water determined by analyzing the test concentrations of 1 and 30 mg/L at 0 hour, 24 hour, 48 hour, 72 hour and 96 hour showed that the test item concentration remained 80% to 120% (between97.83% and 99.27% for 1 mg/L and between97.45% and 99.24% for 30 mg/L) with respect to initial measured concentration and hence the dose verification for definitive test was performed at the beginning and at the termination of the test. Range finding test was conducted with test concentration of 2.80, 5.04, 9.07, 16.33 and 29.39 mg/L along with a control groups without test item by static method. Each concentration contained seven fish. Test item was first formulated in acetone (not exceeding 0.1 ml /L) follwed by natural water. No mortality (percent) observed in control groups and in the tested concentrations of 2.80, 5.04 and 9.07 mg/L whereas, 14.29% and 100% in 16.33 and 29.39 mg/L for a period of 96 hours. No clinical sign observed in control groups and in all the tested concentrations for a period of 96 hours. Based on the results of range finding test, the definitive test was conducted with test concentrations of 10.0, 13.0, 16.9, 22.0 and 28.6 mg/L along with a control groups without test item by static method. Each concentration contained seven fish. Test item was formulated in (not exceeding 0.1 ml /L) follwed by natural water. No mortality (Cumulative mortality percent) observed in control groups and in the tested concentration of 10.0 mg/L and 13.0 mg/L whereas, 42.86%, 57.14%, and 85.71% in 16.9, 22.0 and 28.6 mg/L for a period of 96 hours. No clinical signs observed in control groups and in the tested concentration of 10.0 mg/L whereas, Loss of equilibrium (Loss of buoyancy control) in 16.9, 22.0 and 28.6 mg/L, Abnormal Swimming behaviour (Corkscrew swimming) in 13.0, 16.9, 22.0 and 28.6 mg/L for a period of 96 hours. The test item available in the test medium (natural water) was determined by a validated HPLC method. The test item concentration oftest itemin the test medium at the initiation (0 hour) and 96 hours was 94.79% to 96.23 % for 10.0 mg/L, 94.08 % to 95.02 % for 16.9 mg/L, 95.07% to 95.56 % for 28.6 mg/L % of the nominal test concentrations. As the measured concentrations were within 80 to 120% of the nominal concentration during the definitive test period. Based on the results of the study, the test item,2-methoxynaphthaleneLC₅₀value at 96 hours was found to be 20.18 mg/Lwith 95% confidence limits between19.32 mg/Land21.04 mg/l. Based on the 96 hours LC50 value the test chemical can be categorised in chronic category 3 as per CLP classification criteria.

Long term toxicity to fish

Based on the prediction done using ECOSAR version 1.11, the long term toxicity on fish was predicted for test chemical (2017). On the basis of effects observed in a flow through freshwater system on test organism, the NOEC value for the substance was estimated to be 1.09 mg/l for fish for 28 days of exposure duration. Thus, it can be concluded that the test chemical can be considered as non-toxic to fish at environmentally relevant concentrations.

 

Short term toxicity to aquatic invertebrates

Data available for target chemical and structurally & functionally similar read across analogues, has been reviewed to determine the effect caused on fresh water aquatic organisms. The studies are summarised below:

 

An acute immobilisation test was conducted for 48 hrs for assessing the effect of test chemical on Daphnia magna. The test was performed in accordance to OECD guideline No. 202 “Daphnia sp.,Acute Immobilization Test”. Daphnia magna was used as a test organism for the study. The stock solution 200 g/l was prepared by dissolving white powder in DMSO. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample in reconstituted water. Nominal test chemical concentrations used for the study 0, 5, 10, 20, 30, 40 and 80 mg/l, respectively. Study was performed using 5 organisms per vessel/replicates in a static fresh water system. Daphnids were exposed to test chemical in 50 ml glass vessel in a volume of 25 ml of liquid solution containing both the chemical and media. Control solution vessels containing reconstituted water without the test chemical and reconsituted water, DMSO without the test chemical were also setup during the study. The beakers were placed in a room at a temperature of 20±1°C. In both the control vessels, no daphnids were immobilized at the end of the test. With the test substance one positive control Potassium dichromate (K2Cr2O7) was run simultaneously. EC50 was calculated using non linear regression by the software Prism 4. On the basis of the mobility of the test organism Daphnia magna due to the exposure of test chemical, the 48hr median effect concentration (EC50) value was determined to be 26 mg/l (95 % C. I. - 23.5 to 28.9 mg/l ). Thus, test chemical is considered as toxic to aquatic invertebrates at environmental related concentrations and considered to be classified in 'aquatic chronic category 3' as per the CLP classification criteria.

 

Another short term toxicity to aq. Invertebrate study was conducted for 48 hrs for assessing the effect of test chemical. The study was performed in reconstituted water in a static system at 17°C temperature.Daphnia pulex(Water flea) of less than 24 hr old was used as a test organism for the study.Test organism was fed with 1:1:1:1:4 mixture of four single species of green algae cultures with cerophyl medium (0.3 ng/ml). The resulting conc. of algae (cells/ml) in the daphnid culture water wereChlorella vulgaris(1,700 cells/ml);Chlorella pyrenoidosa(1,300 cells/ml);Ankistrodesmus falcatus(300 cells/ml); andChlamydomonas reinhardii(230 cells/ml). Feeding to the test organism was not done during the test. Total 5 concentrations of test chemical were taken for the study. Exact test chemical conc. was not known. The nominal concentrations of test chemical in each treatment, except the control and highest concentration treatment, were at least 60% of the next higher concentration and fit a geometric progression. Acetone was used as a vehicle. Each test vessel contains atleast 10 neonates/vessel in 150 ml of water. All experiments were performed in 4 replicates. These test vessels were kept at 17°C for an exposure period of 48 hrs. After a period of 48 hrs, immobilization of the test organism was evaluated. The data (percent immobilization at 48 h) were evaluated by probit analysis using a modified version of the IBM SSP package computer program.On the basis of effect on themobility of the test organismDaphnia pulex, the 48 hr EC50 value was determined to be 4.04 mg/l with standard error of ± 0.47.Thus, based on the EC50 value, test chemical can be considered as toxic to aquatic invertebrates at environmental relevant concentrations and considered to be classified in ‘aquatic chronic category 2’ as per the CLP classification criteria.

 

For the test chemical, short term toxicity to aq. Invertebrate study was conducted for 48 hrs for assessing the effect of test chemical. The study was performed in accordance with the EU Method C.2 (Acute Toxicity for Daphnia) under static conditions. Test chemical concentration was verified analytically. Daphnia magna (Water flea) was used as a test organism. On the basis of effect on the mobility of the test organismDaphnia magna(Water flea), the 48 hr EC50 was determined to be 52 mg/l (measured concentration). Based on this value, test chemical can be considered as toxic to aquatic invertebrates and considered to be classified in ‘aquatic chronic category 3’ as per the CLP classification criteria.

 

Additional acute immobilisation test was conducted for 48 hrs for assessing the effect of test chemical on Daphnia magna. The test was performed in accordance to OECD guideline No. 202 “Daphnia sp.,Acute Immobilization Test”. Daphnia magna was used as a test organism for the study. The stock solution 100 mg/l was prepared by dissolving white powder in acetone. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample in reconstituted water. Nominal test chemical concentrations used for the study 0, 0, 1.2, 2.5, 5, 10, 20 and 40 mg/l, respectively. Study was performed using 5 organisms per vessel/replicates in a static fresh water system. Daphnids were exposed to test chemical in 50 ml glass vessel in a volume of 25 ml of liquid solution containing both the chemical and media. Control solution vessels containing reconstituted water and reconsitituted water including acetone without the test chemical were also setup during the study. The beakers were placed in a room at a temperature of 20±1°C. With the test substance one positive control Potassium dichromate (K2Cr2O7) was run simultaneously. EC50 was calculated using non linear regression by the software Prism 4. On the basis of the mobility of the test organism Daphnia magna due to the exposure of test chemical, the 48hr median effect concentration (EC50) value was determined to be 48.1 mg/l (95 % C. I. - 39.3 to 58.9 mg/l ). Thus, test chemical is considered as toxic to aquatic invertebrates at environmental related concentrations and considered to be classified in 'aquatic chronic category 3' as per the CLP classification criteria.

 

On the basis of the review from expert judgements and considering the study results conducted as per the OECD guideline 202 for the target chemical by applying the weight of evidence approach, it is concluded that the test chemical can be consideredastoxic to aquatic invertebrates at environmental related concentrations and considered to be classified in 'aquatic chronic category 3' as per the CLP classification criteria.

 

Long term toxicity to aquatic invertebrates

The study outlines the adverse effects of test chemical on reproduction of Daphnia magna, the test was conducted following the OECD guidelines 211 (Experimental study report, 2018). A semi static regime was followed in which the test chemical was renewed at every alternate day till 21 days of study. Nominal concentrations were used i.e., from of 0.625 mg/L, 1.25 mg/L, 2.5 mg/L, 5 mg/L and 10 mg/L, and reproduction effect was studied for 21 days based on the number of off springs produced. All the validity criteria were fulfilled per OECD guidelines. The median effective concentration (EC50) and effective concentration at 10% inhibition was determined as 5.89±1.76 and 1.20± 0.6 mg/L, respectively. Thus, it can be concluded that the test chemical can be considered as non-toxic to aquatic invertebrate at environmentally relevant concentrations.

 

Toxicity to aquatic algae and cyanobacteria

Data available for target chemical and structurally & functionally similar read across analogues, has been reviewed to determine the effect caused on fresh water algae. The studies are summarised below:

 

In an experimental study, toxicity to aquatic algae study was conducted for 72 hrs for assessing the effect of test chemical on Desmodesmus subspicatus. The test was performed in accordance to OECD Guideline 201 (Alga, Growth Inhibition Test). Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) of strain 86.81 SAG obtained from Institute of botany of the ASCR with an initial biomass conc. 5x10(3) cells /ml was used as a test organism. The stock solution 10.0 g/l was prepared by dissolving white powder in DMSO. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Nominal test chemical conc. used for the study were 0, 0.35, 0.70, 1.4, 2.8 and 5.6 mg/l, respectively. Study was performed using Desmodesmus subspicatus as a test organism in a static fresh water system. Desmodesmus subspicatus were exposed to test chemical in 100 ml glass vessel in a volume of 30 ml of liquid solution containing both the chemical and media. The beakers were placed in a room at a temperature of 23±2°C with a continuous light intensity of 6000-8000 lx, respectively. Alongwith the test chemical, one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. Solvent control was also run simulatenously during the test. Cell counting was carried out using microscope with counting chamber Cyrus I or electronic particle counter. ErC50 was calculated using non-linear regression by the software Prism 4.0. On the basis of the effect of test chemical on the growth rate of the test organism Desmodesmus subspicatus, the 72 hr median effect concentration (ErC50) value was determined to be 4.93 mg/l (95 % CI 4.83 - 5.02 mg/l).

 

Another algal growth inhibition test was conducted for 96 hrs for assessing the growth inhibition potentialof test chemical on green algae.The test was performed following the ASTM International Standards method (1988) under static condition for 96 hrs. Analytical monitoring of test chemical concentrations were carried out by GC analysis.Test organism green algae (10000 cells/ml) were exposed to five different conc. of test chemical, i. e.,0, 12.5, 25, 50 and 100 mg/l in 125 ml flasks for a period of 96 hrs. These test vessels were shaken continuously. All experiments were performed in four replicates. IC50 was calculated using a linear interpolation program. On the basis of the effect on growth of the test organism green algae,the 96 hrs IC50 value was determined to be 9.57 mg/l (95% C. I. = 7.434 to 13.274). 

 

In a supporting weight of evidence study, toxicity to aquatic algae study was conducted for 72 hrs for assessing the effect of test chemical on Desmodesmus subspicatus. The test was performed in accordance to OECD Guideline 201 (Alga, Growth Inhibition Test). Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) of strain 86.81 SAG with an initial biomass conc. 5x10(3) cells /ml was used as a test organism. The stock solution 100 g/l was prepared by dissolving white powder in acetone and it was 10 times diluted by acetone. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Nominal test chemical conc. used for the study were 0, 0, 2, 3.6, 6.5, 12 and 21 mg/l, respectively. Study was performed using Desmodesmus subspicatus as a test organism in a static fresh water system. Desmodesmus subspicatus were exposed to test chemical in 50 ml glass vessel in a volume of 15 ml of liquid solution containing both the chemical and media. The beakers were placed in a room at a temperature of 23±2°C with a continuous light intensity of 6000-8000 lx, respectively. Alongwith the test chemical, one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. Solvent control was also run simulatenously during the test. Cell counting was carried out using microscope with counting chamber Cyrus I or electronic particle counter. ErC50 was calculated using non-linear regression by the software Prism 4.0. On the basis of the effect of test chemical on the growth rate of the test organism Desmodesmus subspicatus, the 72 hr median effect concentration (ErC50) value was determined to be 8.9 mg/l (95 % CI 8.0 - 10.0 mg/l).

 

On the basis of the experimental studies of the functionally similar read across chemical and applying the weight of evidence approach, the 72/96 hr ErC50 value of the test chemical on test organism green algae was determined to be in the range 4.93 to 9.571 mg/l, respectively. Thus, based on the ErC50 value, test chemical can be considered to be toxic to aquatic algae and considered to be classified in 'aquatic chronic category 2' as per the CLP classification criteria.

 

Toxicity to microorganisms

Data available for the structurally and functionally similar read across chemicals has been reviewed to determine the toxic effect of the test chemical on microorganisms. The studies are as mentioned below:

 

Aquatic toxicity study of micro-organism to the test chemical was conducted using Photobacterium phosphoreum, strain NRRL-B-11177 (also referred to as Vibrio fischerii, strain NRRL-B-11177). The study was performed at a temperature of 15ᵒC and pH range 5 to 9, respectively. Recommneded reference substance that can be used for the study were Phenol and Sodium pentachlorophenate, respectively. When the test bacterium Photobacterium phosphoreum, strain NRRL-B-11177 was exposed to the test chemical, reduction in light output was observed. Thus, based on this effect, the 30 mins EC50 value was determined to be 19 mg/l.

 

Another toxicity to Tetrahymena thermophile study was carried out at 32°C.The study was based on the effects of the test chemical on test organism. On the basis of the effect on growth rate of the test organism Tetrahymena thermophila, the 48 hr EC50 value was determined to be 13.5 mg/l.

 

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach, the EC50 value of the test chemical on test organism can be expected to be ranges from 13.5 to 19 mg/l.

 

On the basis of the available information of aquatic toxicity studies, it can be concluded that the test chemical can be considered as toxicto aquatic organisms at environmental relevant concentrations and considered to be classified in 'aquatic chronic category 2' as per CLP classification criteria.