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Description of key information

Short term toxicity to fish:

This study was designed to assess the toxic effects of the test compound on the Zebra fish. A static procedure was used for the study and it was conducted in compliance with the OECD guideline 203. Test conducted under the static system for 96 hrs under the static system. The test substance was soluble in water. Therefore, the test solution was prepared by dissolving 6.24 mg, 12.5 mg, 25 mg, 50 mg & 100 of the test substance in 4 liters of potable water (passed through reverse osmosis system) with continuous stirring for achieving test concentrations of 1.56 mg/L, 3.125 mg/L, 6.25 mg/L, 12.5 mg/L & 25 mg/L, respectively. Based on the nominal concentrations, the median lethal concentration LC50 (96 h) for test chemical on Danio rerio was observed to be 1.56 mg/L. Thus based on the LC50 value, chemical consider to be toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

Long term toxicity to fish:

Using the EPI Suite, the long term toxicity on fish was predicted for test substance. On the basis of no effects observed in a freshwater system, the no observed effect concentration (NOEC) value for the substance is estimated to be 0.761 mg/l for fish for 28 d duration.

 

Short term toxicity to aquatic invertebrates:

Short term toxicity of test chemical were evaluated by observing the effects of chemical on the ability to detach from substrate. Test conducted under the static system on 5-8 MM shell length of Dreissena polymorpha. The 48 hour EC50 value of test chemical in invertebrate (Dreissena polymorpha) was determine to be 3.4 mg/L on the basis of effect on ability to detach from substrate. This value indicates that the chemical will exhibit short term toxicity to invertebrates. As per the CLP criteria, this classification amounts to Aquatic Chronic Category 2.

Long term toxicity to aquatic invertebrates:

Using the EPI Suite, the long term toxicity on aquatic invertebrate daphnia magna was predicted for test substance. On the basis of no effects observed in a freshwater system, the no observed effect concentration (NOEC) value for the substance is estimated to be 0.619 mg/l for invertebrate daphnia for 21 d duration. Based on the NOEC value, chemical consider to be toxic and classified sa aquatic chronic 2 as per the CLP classification criteria.

 

Toxicity to aquatic algae and cyanobacteria:

This study was designed to access the toxic effects of the test compound on the green alga Chlorella vulgaris. Test was conducted in compliance with the OECD guideline 201 (Alga, Growth Inhibition Test). The test solution was prepared in aseptic condition. The test substance Tert-butyl-4-methoxyphenol was prepared by adding 10 mg of test substance in 100 ml of BBM to get the final concentration of 100 mg/L. The remaining test solutions were prepared by dilution from the above stock solution. To have a better growth and visibility of cells, the initial cell density of the culture was kept 1 X 104cells/ml. Care was taken to have a homogeneous solution for the experiment. The effect of the test substance on the green algae Chlorella vulgaris culture was observed at nominal test concentration of 1.5, 2.7, 4.86, 8.748, 15.75 and 28.34 mg/L. For the assessment of algal growth, the test was conducted in replicates. The control flask was maintained in triplicates as recommended in the OECD guideline and the test concentration were selected in geometric series which were maintained in duplicates. To obtain a quantitative concentration-response relationship by regression analysis, a linearizing transformation of the response data into probit was performed. Using the same, effective concentration (EC) were determined. The microscopic observations were also noted in each of the experimental flasks. All the cells appeared healthy, round and green throughout the test duration in the control while following changes were observed at the higher concentrations. Decreased in cell count and reduced cell size.  After 72 hours of exposure to test substance to various nominal test concentration, EC50 calculated from equation and graphically through probit analysis was observed to be 9.05 mg/L and 9.33 mg/L respectively.

Toxicity to microorganisms:

1: Based on the effect observed on the Population growth rate inhibition of Tetrahymena thermophile (Ciliate Protozoa) during the exposure period of 48 hrs, the EC50 was determine to be 2.55 mg/l.

2: Based on the effect observed on the Population growth rate inhibition of Tetrahymena thermophile (Ciliate Protozoa) during the exposure period of 48 hrs, the EC50 was determine to be 2.9 mg/l.

Thus based on the above effects observed on microorganisms, toxicity ranges from 2.55 mg/l to 2.9 mg/l.

Additional information

Summarized result for the toxicity of test chemical on the growth and mortality of aquatic life’s including fish, invertebrates, algae and microorganism were studied and are as mention below:

 

Short term toxicity to fish:

Summarized result for the toxicity of test chemical on the mortality of fishes were reviewed and mention as below:

This study was designed to assess the toxic effects of the test compound on the Zebra fish. A static procedure was used for the study and it was conducted in compliance with the OECD guideline 203. Test conducted under the static system for 96 hrs under the static system. The test substance was soluble in water. Therefore, the test solution was prepared by dissolving 6.24 mg, 12.5 mg, 25 mg, 50 mg & 100 of the test substance in 4 liters of potable water (passed through reverse osmosis system) with continuous stirring for achieving test concentrations of 1.56 mg/L, 3.125 mg/L, 6.25 mg/L, 12.5 mg/L & 25 mg/L, respectively. Based on the nominal concentrations, the median lethal concentration LC50 (96 h) for test chemical on Danio rerio was observed to be 1.56 mg/L. Thus based on the LC50 value, chemical consider to be toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

 

Above experimental study was supported by the second supporting data from authoritative database. Short term toxicity of test chemical were studied on the mortality of fish. Test conducted under the static system for 96 hrs. The 96 hour LC50 value of test chemical in fish was determine to be 5.8 mg/L. Thus based on the LC50 value, chemical consider to be toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

 

Similar acute toxicity of fish were determine on the mortality rate of fishes Lepomis macrochirus. Juvenile Lepomis macrochirus were used in the study. Test conducted under the static system for 48 hrs. After the 48 hrs of incubation effects on the mortality rate of fishes were observed. Based on the mortality the 48 hour LC50 value of test chemical in fish (Lepomis macrochirus) was determine to be 4.8 with 95 % CI of (4.5-5.0) mg/L. Hence on the basis of LC50 value, chemical consider to be toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

 

In the fourth acute toxicity of test chemical were determine on the mortality rate of fish Ictalurus punctatus. Based on the mortality of fish (Ictalurus punctatus) by the chemical exposure for 48 hrs, the LC50 value was determine to be 1.5 mg/L.

 

Similar short term toxicity of test chemical on the mortality of fish were studied. Test conducted under the static system for 24 hrs. The 24 hour LC50 value of test chemical in Oryzias latipes was observed to be 5.6 mg/L at 20°C and 5.5mg/L at 10°C on the basis of mortality. These values indicate that the chemical will exhibit short term toxicity to fish. As per the CLP criteria, the substance will be classified in Aquatic Chronic Category 2.

 

Objective of this sixth study was to determine the effect of test chemical on the mortality of fish Oryzias latipes. Test conducted under the static system for 48 hrs. The 48 hour LC50 value of test chemical in fish (Oryzias latipes) was observed to be 5 mg/L at 20°C.

 

Thus based on the overall studies for the test chemical, it was concluded that the chemical was toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

 

Long term toxicity to fish:

Using the EPI Suite, the long term toxicity on fish was predicted for test substance. On the basis of no effects observed in a freshwater system, the no observed effect concentration (NOEC) value for the substance is estimated to be 0.761 mg/l for fish for 28 d duration.

 

Short term toxicity to aquatic invertebrates:

Summarized result for the toxicity of test chemical on the mobility of aquatic invertebrates were reviewed and mention as below:

Short term toxicity of test chemical were evaluated by observing the effects of chemical on the ability to detach from substrate. Test conducted under the static system on 5-8 MM shell length of Dreissena polymorpha. The 48 hour EC50 value of test chemical in invertebrate (Dreissena polymorpha) was determine to be 3.4 mg/L on the basis of effect on ability to detach from substrate. This value indicates that the chemical will exhibit short term toxicity to invertebrates. As per the CLP criteria, this classification amounts to Aquatic Chronic Category 2.

 

Above study was supported by the second experimental study from peer reviewed journal. Short term toxicity of test chemical were studied on the mobility of daphnia magna. The 48 hour EC50 value of test chemical in Daphnia magna was determine to be 2.3 mg/L on the basis of mobility. This value indicates that the chemical will exhibit short term toxicity to fish. As per the CLP criteria, this classification amounts to Aquatic Chronic Category 2.

 

Objective of the present study was to evaluate the effect of chemical on aquatic mollusc Dreissena polymorpha. The effective concentration (EC50) value of test chemical in aquatic mollusc [zebra mussels (Dreissena polymorpha)] in a 48 hr study on the basis of effect on attachment was consider to be in the range 19.4 to 29 mg/L. Thus based on the above effects observation, chemical consider to be toxic and classified as aquatic chronic 3 as per the CLP classification criteria.

 

Similar short term toxicity of test chemical were evaluated by observing the effects of chemical on the aquatic mollusc. The lethal concentration (LC50) value of test chemical in Dreissena polymorpha in a 48 hr study on the effect basis of mortality was observed to be 65 mg/L. Thus based on the above effects observation, chemical consider to be toxic and classified as aquatic chronic 3 as per the CLP classification criteria.

 

Based on the above two studies, chemical consider to be toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

 

Long term toxicity to aquatic invertebrates:

Using the EPI Suite, the long term toxicity on aquatic invertebrate daphnia magna was predicted for test substance. On the basis of no effects observed in a freshwater system, the no observed effect concentration (NOEC) value for the substance is estimated to be 0.619 mg/l for invertebrate daphnia for 21 d duration. Based on the NOEC value, chemical consider to be toxic and classified sa aquatic chronic 2 as per the CLP classification criteria.

 

Toxicity to aquatic algae and cyanobacteria:

Based on the various data for the test chemical, studies were reviewed for the toxicity evaluation on the growth of algae and cyanobacteria end point which are summarized as below: 

This study was designed to access the toxic effects of the test compound on the green alga Chlorella vulgaris. Test was conducted in compliance with the OECD guideline 201 (Alga, Growth Inhibition Test). The test solution was prepared in aseptic condition. The test substance Tert-butyl-4-methoxyphenol was prepared by adding 10 mg of test substance in 100 ml of BBM to get the final concentration of 100 mg/L. The remaining test solutions were prepared by dilution from the above stock solution. To have a better growth and visibility of cells, the initial cell density of the culture was kept 1 X 104cells/ml. Care was taken to have a homogeneous solution for the experiment. The effect of the test substance on the green algae Chlorella vulgaris culture was observed at nominal test concentration of 1.5, 2.7, 4.86, 8.748, 15.75 and 28.34 mg/L. For the assessment of algal growth, the test was conducted in replicates. The control flask was maintained in triplicates as recommended in the OECD guideline and the test concentration were selected in geometric series which were maintained in duplicates. To obtain a quantitative concentration-response relationship by regression analysis, a linearizing transformation of the response data into probit was performed. Using the same, effective concentration (EC) were determined. The microscopic observations were also noted in each of the experimental flasks. All the cells appeared healthy, round and green throughout the test duration in the control while following changes were observed at the higher concentrations. Decreased in cell count and reduced cell size.  After 72 hours of exposure to test substance to various nominal test concentration, EC50 calculated from equation and graphically through probit analysis was observed to be 9.05 mg/L and 9.33 mg/L respectively.

 

Determination of short term toxicity of test chemical on the growth of aquatic algae and cyanobacteria. Test conducted for 72 hrs. Effect were observed on the basis of growth rate inhibition and area under the growth curve. The 72 hour EC50 value of test chemical in green algae was determine to be 1.9 mg/L based on its effect on the growth rate (area under the growth curve) and 5.2 on the basis of growth rate. The NOEC was observed at 0.25 mg/l. Thus based on the EC50 value, chemical consider to be toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

 

Thus based on the above effects, chemical consider to be toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

Toxicity to microorganisms:

Various studies available for the test chemical and structurally and functionally similar read across chemicals were reviewed to determine the toxic nature of test chemical on the population rate and growth of microorganisms. The studies are as mentioned below:

 

In the first study for read across chemical toxicological study was conducted to determine the nature and effect of test chemical when comes in contact with the Tetrahymena Thermophile. Test performed for the total exposure period of 48 hrs. Based on the effect observed on the Population growth rate inhibition of Tetrahymena thermophile (Ciliate Protozoa) during the exposure period of 48 hrs, the EC50 was determine to be 2.55 mg/l. Based on the effect observed on the microorganisms, chemical was consider as toxic.

 

Above study was supported by the second supporting study from authoritative database 2018. Toxicological study was conducted to determine the nature and effect of test chemical when comes in contact with the Tetrahymena Thermophile. Test performed for the total exposure period of 48 hrs. Based on the effect observed on the Population growth rate inhibition of Tetrahymena thermophile (Ciliate Protozoa) during the exposure period of 48 hrs, the EC50 was determine to be 2.9 mg/l. Based on the effect observed on the microorganisms, chemical was consider as toxic.

 

Thus based on the above effects observed on microorganisms, toxicity ranges from 2.55 mg/l to 2.9 mg/l.