N,N-dimethyl-p-toluidine

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). Study was performed in compliance with OECD 203 Guideline for the testing of chemicals; Fish, Acute Toxicity Testing, (18th June, 2019). Test chemical was directly dissolved in water without using any carrier solvent, prepared by dissolving 3000 mg in 3000ml on 0^thday. However, since it was a semi static assay therefore the stock solution was prepared daily, and the solubility is determined on daily basis to prepare the test concentrations. On 1st, 2nd, and 3rd day stock solution was prepared by dissolving 1000 mg in 1000 ml of RO water to get the final concentration of 1000 mg/L which was then analytically determined. From stock solutions exposure concentrations were prepared by dilutions. Since the chemical was unstable in exposure media, semi static condition was chosen for main study. The main study was conducted with 5 concentrations based on the previously available data, i.e., 9.62, 17.32, 31.18, 56.12 and 101.01 mg/L with a geometric factor of 1.8 along with one control group. The test concentration was renewed at regular 24 hours of intervals. Each concentration contained seven fish. The test conditions such as temperature, hardness, pH dissolved oxygen and conductivity was 22.4±0.9, 140mg of CaCO3, 8.3 -7.7, 7.0 – 7.1 and 0.4µS/cm respectively. No mortality (percent) observed in control groups and in the tested concentrations of 9.62, 17.32, 31.18, 56.12 mg/L whereas, 100% in 101.01 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 expect in the highest concentrations fishes were swimming near water surface and movement was slow compared with control. The test item available in the test medium was determined by a validated spectrophotometric method. The test item concentration of test item in the test medium at the initiation 0 hour, 24 hours, 48 hours, 72 hours and 96 hours was measured in all exposed concentrations. which were in the range of 100±20 of the nominal test concentrations presented in additional information on results. As the measured concentrations were within 80 to 120% of the nominal concentration during the definitive test period. Based on the re mortality the median lethal concentration was reported to be > 56.12 (nominal) and 78.62 mg/L (geometric average LC0 and LC100). Based on the 96 hours LC50 value the test chemical can be categorized in chronic category 3 as per CLP classification criteria.

Short-term toxicity to aquatic invertebrates:

The effect of test chemical was studied on fresh water invertebrate daphnia magna STRAUS strain by following OECD 202 guidelines adopted on 13 april 2014, to assess the acute toxicity of test chemical following exposure of daphnids up to 48h by static method. The brood daphnids were acclimatized 48 hours prior to the test item exposure. Less than 24 h old daphnids were collected from the acclimatized gravid females and exposed to the test item. After exposure on day 0, daphnids were observed for immobilization at 24 and 48 h. M7 medium was used as control, and the same was used for test item formulation . 25 mL glass beakers having a solution volume of 20 mL were used in the test. . Main study (using a spacing factor of 2) was conducted using 0 (control), 2.5,5,10,20,40 mg/L mg/L concentrations. 4 replicates/concentration having 5 daphnids/replicate was used for the main study. Normal behavioural response and no immobilization (0% mortality) were observed up to 48 h in control groups but 25%, 30%, 45% 75% and 100% immobilisation were observed in the test concentrations of  2.5,5,10,20,40 mg/L, respectively. UV-Visible spectrophotometer method was used for active ingredient analysis along with stability of the test item in the test medium. Test item was found to be unstable in the test medium. The active ingredient content results were not within the considered acceptable (80 -120%) as during main study 0 h and 48 h avg. recovery for 2.5,5,10,20,40 mg/L, conc at 0 hour were 88.8%, 82.4%, 81.1%, 84.5% and 82.2% respectively. after 48 hours of exposure, which were found to not in acceptable range. Hence the results were based on measure and nominal concentration since the deviation in the initial measured concentration exceed 20%. Environmental parameters such as pH (7.9 -7.2), temperature (19.7 ± 0.7 °C), dissolve oxygen (7.6 - 7.2 mg/L), hardness (>140 mg CaCO3/L), conductivity (0.20 µS/cm), photoperiod (16 h light- 8 h dark) was maintained in acceptable range throughout the test. Feed was not provided during the test. The 48-h EC50of test chemical to daphnid, Daphnia magna are 10.34 mg/L ( nominl concentration) and 8.44 mg/L ( Initial Measured concentration). The 48-h EC50of reference item (Potassium dichromate) to daphnid, Daphnia magna(found to be in acceptable range) is 1.33 mg/L. Hence, the results of the test with reference item establish the acceptability of the test system response, test procedures followed, and results obtained with test item. 48h EC50 value with 95% confidence limits (upper limit, lower limit) were calculated by probit analysis using STAT plus Software, version 8. Hence, as per CLP classification category the test chemical can be categorized as Chronic Category 3.

Toxicity to aquatic algae and cyanobacteria:

The effect of test chemical on fresh water algae was studied by following OECD 201 guidelines using P subcapitata as test system. The mother culture was maintained in the same conditions of the test. From this preculture flask was taken and incubated for 3 days to attain the exponential growth. Cells from the exponential growth was taken for the main study. Based on the available data, main study was directly conducted with 5 test concentrations. The test substance was dissolved in the OECD medium and stirring was provided, to distribute chemical homogeniously, which was further analytically determined using UV visible spectrophotometer. Test concentrations selected for the study are 8, 12, 18, 27 and 40.5 mg/L separated with a factor of 1.5. Each test concentration was maintained in the triplicates along with control in 100 ml conical flask with 60 ml of test solution including test system. The algal cell count in each flask was 10000 cell/ ml at day 0. All the flasks were placed in an incubator and maintained for the period of 72 hours at a temperature of 21.8°C. The cell count was done using Neubauer chamber under microscope at regular 24 hours i.e., day0, day1 day 2 and day3 in all test vessels. The pH at the day 0 and day 3 was 7.5 and 8.3 respectively. The percent inhibition of cell growth at concentrations 8, 12, 18, 27, 40.5 was 8.5%, 15.58%, 17.13%, 28.55% and 65.55% respectively. All the test concentrations were analyzed for actual test substance, at 0 hours and 72 hours. which were not maintained within 80 -120% of the nominal concentrations, thus geometric mean was reported. The biomass of the control cultures have increased exponentially by a factor of 22.83 (specific growth rate 1.04 day-1) within the 72 hr period which is following the validity criteria of biomass in the control cultures of factor 16 (specific growth rate of 0.92 day-1) within the 72 hr test periods. The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hr tests) in the control cultures is9.52 %, thereby meeting the 35% validity criteria. The mean coefficient of variation of average specific growth rates during the whole test period in replicate control culture was found to be2.81 %and it must not be exceed 7% in the tests with Pseudokirchneriella subcapitata. 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 (ErC) were determined. thus EC50 was reported in geometric mean measured concentration of 0 hours and 72 hours. Based on outcomes of growth rates EC50 was reported to be 23.69mg/l (measured) and 35.65 mg/l (nominal). Thus chemical can be classified into aquatic chronic category 3 as per CLP classification criteria

Toxicity to microorganisms:

The toxicity study were carried out on the activated sludge and Pseudomonas putida. The effective concentration (EC50) value for test material on domestic activated sludge in a 3 hours study were determined to be 100 mg/L and based on the growth rate inhibition of Pseudomonas putida due to the test chemical exposure for 16 hours, the EC0 value was determined to be 29 mg/l.

Additional information

Short-term toxicity to fish:

Based on the various experimental studies from different sources including peer reviewed journal, authoritative databases and secondary databases, studies were reviewed for the determination of the effects of test chemical on the mortality of fishes. The studies are as mentioned below:

The objective of this study is to assess the Acute Toxicity of test chemical in Freshwater Fish (Danio rerio). Study was performed in compliance with OECD 203 Guideline for the testing of chemicals; Fish, Acute Toxicity Testing, (18th June, 2019). Test chemical was directly dissolved in water without using any carrier solvent, prepared by dissolving 3000 mg in 3000ml on 0^thday. However, since it was a semi static assay therefore the stock solution was prepared daily, and the solubility is determined on daily basis to prepare the test concentrations. On 1st, 2nd, and 3rd day stock solution was prepared by dissolving 1000 mg in 1000 ml of RO water to get the final concentration of 1000 mg/L which was then analytically determined. From stock solutions exposure concentrations were prepared by dilutions. Since the chemical was unstable in exposure media, semi static condition was chosen for main study. The main study was conducted with 5 concentrations based on the previously available data, i.e., 9.62, 17.32, 31.18, 56.12 and 101.01 mg/L with a geometric factor of 1.8 along with one control group. The test concentration was renewed at regular 24 hours of intervals. Each concentration contained seven fish. The test conditions such as temperature, hardness, pH dissolved oxygen and conductivity was 22.4±0.9, 140mg of CaCO3, 8.3 -7.7, 7.0 – 7.1 and 0.4µS/cm respectively. No mortality (percent) observed in control groups and in the tested concentrations of 9.62, 17.32, 31.18, 56.12 mg/L whereas, 100% in 101.01 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 expect in the highest concentrations fishes were swimming near water surface and movement was slow compared with control. The test item available in the test medium was determined by a validated spectrophotometric method. The test item concentration of test item in the test medium at the initiation 0 hour, 24 hours, 48 hours, 72 hours and 96 hours was measured in all exposed concentrations. which were in the range of 100±20 of the nominal test concentrations presented in additional information on results. As the measured concentrations were within 80 to 120% of the nominal concentration during the definitive test period. Based on the re mortality the median lethal concentration was reported to be > 56.12 (nominal) and 78.62 mg/L (geometric average LC0 and LC100). Based on the 96 hours LC50 value the test chemical can be categorized in chronic category 3 as per CLP classification criteria.

An acute study was carried out for the determination of effects of test chemical on the mortality rate of fishes. Test conducted in accordance withStandard test procedure ASTM. Newly hatched fry (<24-h-old) or 28- to 34-day-old juvenile pimephales promelas was used as a test organism. Nominal test concentrations ranges from 42 to 50.5 mg/L were used. Test performed under thestatic systemfor providing the exposure period of 96 hours. 5 fishes were added in each test and control chamber. All fish were acclimated to the test chambers for 2-3 h before introduction of the toxicants. The fish were not fed 24 h before nor during the toxicity tests.Mortality were recorded dailyand the LC50 values and 95 % confidence intervals were computed by the Trimmed Spearman-Karber Method or a log-probit method. Based on the mortality of fathead minnows (Pimephales promelas) due to the test chemical exposure for 96 hours, the lethal concentration (LC50) value was determined to be at 52.8 mg/l. This LC50 value indicates that the test material was toxic to fish Pimephales promelas and classified in aquaticchronic category 3as per the CLP classification criteria.

 

Above study further supported by the second study from peer reviewed journal. Principle of this study was to determine the effect of test chemical on the mortality rate of freshwater fishes. Test conducted in accordance withJapan industrial standards. Oryzias latipes was used as a test organism.10 fishes in one trial were used and kept in 2 liters of deionized water.After 48 hours of study, lethal concentration of 50% mortality were determined. Median Tolerance limit (TLm) value of test chemical to fish Oryzias latipes in 24- and 48-hours study on the basis of mortality effect was examined at dose concentration of 44 mg/l and 20 mg/L. This Value indicates that the test chemical was toxic to fish Oryzias latipes.

 

Similarly, in the third supporting study an acute effects of test chemical on fishes Pimephales promelas was determined. Test conducted under theflow-through system for 96 hours. 35 days old Pimephales promelas was used as a test organism. Fishes were collected from US EPA Environmental Research Laboratory. After the exposure period of 96 hours effects on the mortality of fishes were observed.Affected fish lost schooling behaviour and swam near the tank bottom. They were hypoactive and underreactive to external stumuli and has increased respiration.Equilibriums loss was not observed prior to death. Alkalinity value increased with the exposure concentration. Lethal concentration LC50 value and the Effective concentration EC50 value of test chemical to Pimephales promelas in 96 hours study on the basis of mortality effect was determined at dose concentration 52 mg/L. This value indicates that the test chemical was toxic to fishes and classified in aquatic chronic category 3 as per the CLP classification criteria.

 

Principle of this study was to determine the acute effects of test chemical on the mortality of fishes. 32 days old Pimephales promelas was used a test organism. Test conducted under the flow-through system for 96 hours. 0, 19.2, 29.6, 45.6, 70.2 and 108 mg/L nominal test concentrations ere used in the study. Affected fish lost schooling behaviours and swam near the tank bottom. They were hypoactive and underreactive to external stumuli and has increased respiration. Initial dissolve oxygen values were less than 60% of saturation. equilibrium loss was not observed prior to death. The measured tank value was lower than the nominal values. Alkalinity value increased with the exposure concentration. They were due to a reaction between the titrant and the toxicant. Lethal concentration (LC50) value of test chemical to fish in 96 hours study on the basis of mortality effect was examined at dose concentration of 46 mg/L. Effective concentration (EC50) value of test material to Pimephales promelas in 96 hours study on the basis of mortality effect was determined at dose concentration of 41.5 mg/L. This value indicates that the test chemical was toxic to fishes and classified in aquatic chronic category 3 as per the CLP classification criteria.

 

The fifth study was also supporting the classification of target chemical. Principle of this study was to determine the effect of test chemical on the mortality rate of fishes. Test conducted under theflow through system for 96 hours. Freshwater Pimephales promelas was used as a test organism. After the exposure of chemical with fishes, effects on the mortality rate were measured. The effect of the test material on fishes Pimephales promelas was evaluated for 96 h in flow through condition. The Lethal concentration i.e. LC50 value of test chemical was observed to be 48.9 mg/l. Thus, on the basis of LC50 value, test chemical considered to be toxic and classified in aquatic chronic category 3 as per the CLP classification criteria.

 

Thus, on the basis of above all studies from various sources, test chemical considers to be toxic and classified in aquatic chronic category 3 as per the CLP classification criteria.

Short-term toxicity to aquatic invertebrates:

Based on the various predicted and experimental studies from different sources, studies were reviewed for the determination of the effects of test chemical and structurally and functionally similar read across chemicals on the mobility of aquatic invertebrates. The studies are as mentioned below:

 

The effect of test chemical was studied on fresh water invertebrate daphnia magna STRAUS strain by following OECD 202 guidelines adopted on 13 april 2014, to assess the acute toxicity of test chemical following exposure of daphnids up to 48h by static method. The brood daphnids were acclimatized 48 hours prior to the test item exposure. Less than 24 h old daphnids were collected from the acclimatized gravid females and exposed to the test item. After exposure on day 0, daphnids were observed for immobilization at 24 and 48 h. M7 medium was used as control, and the same was used for test item formulation . 25 mL glass beakers having a solution volume of 20 mL were used in the test. . Main study (using a spacing factor of 2) was conducted using 0 (control), 2.5,5,10,20,40 mg/L mg/L concentrations. 4 replicates/concentration having 5 daphnids/replicate was used for the main study. Normal behavioural response and no immobilization (0% mortality) were observed up to 48 h in control groups but 25%, 30%, 45% 75% and 100% immobilisation were observed in the test concentrations of  2.5,5,10,20,40 mg/L, respectively. UV-Visible spectrophotometer method was used for active ingredient analysis along with stability of the test item in the test medium. Test item was found to be unstable in the test medium. The active ingredient content results were not within the considered acceptable (80 -120%) as during main study 0 h and 48 h avg. recovery for 2.5,5,10,20,40 mg/L, conc at 0 hour were 88.8%, 82.4%, 81.1%, 84.5% and 82.2% respectively. after 48 hours of exposure, which were found to not in acceptable range. Hence the results were based on measure and nominal concentration since the deviation in the initial measured concentration exceed 20%. Environmental parameters such as pH (7.9 -7.2), temperature (19.7 ± 0.7 °C), dissolve oxygen (7.6 - 7.2 mg/L), hardness (>140 mg CaCO3/L), conductivity (0.20 µS/cm), photoperiod (16 h light- 8 h dark) was maintained in acceptable range throughout the test. Feed was not provided during the test. The 48-h EC50of test chemical to daphnid, Daphnia magna are 10.34 mg/L ( nominl concentration) and 8.44 mg/L ( Initial Measured concentration). The 48-h EC50of reference item (Potassium dichromate) to daphnid, Daphnia magna(found to be in acceptable range) is 1.33 mg/L. Hence, the results of the test with reference item establish the acceptability of the test system response, test procedures followed, and results obtained with test item. 48h EC50 value with 95% confidence limits (upper limit, lower limit) were calculated by probit analysis using STAT plus Software, version 8. Hence, as per CLP classification category the test chemical can be categorized as Chronic Category 3.

 

Above data further supported by the second study from peer reviewed journal. Principle of this study was to determine the effect of test chemical on the mobility of aquatic invertebrates. 24 hours old Daphnia magna was used as a test organism. The stock solutions were prepared before 24 hours of the experiments in Dutch standard water (DSW) and stirred until use. Test organism were starved from 24 hours before the experiment until the end, when they were sacrificed by immersion in liquid nitrogen. Test conducted under the static system by providing the exposure period of 48 hours of chemical with aquatic invertebrates Daphnia magna. Based on the immobility of Daphnia magna due to the test chemical exposure for 48 hours, the EC50 value was determined to be 13.7 mg/l. This value indicates that the test chemical was toxic and classified in aquatic chronic category 3 as per the CLP classification criteria.

 

Similarly in this experimental study the effect of test chemical was studied on the immobility of aquatic invertebrate Daphnia magna. Test conducted under the static system for 48 hours. Based on the data obtained from the reliable sources, the immobility of Daphnia magna due to the test chemical exposure was observed. The EC50 value was observed to be at 15 mg/l after the exposure period of 48 hours. Thus, based on the EC50 value, test chemical considers to be toxic and classified in aquatic chronic category 3 as per the CLP classification criteria.

Similarly,an acute immobilisation test was conducted for 48 hrs for assessing the short-term toxicity of test chemical to aquatic invertebrate.Study was performed according to the “OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)”.Daphnia magna was used a test organism. The stock solution 100 g/L was prepared in solvent acetone. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample in reconstituted test water.0, 5, 10, 20, 40 and 80 mg/L respectively nominal concentrations were used in this study.Effects on immobilisation were observed for 48 hours and conducted under the static system. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical,effect concentration EC50 value was calculated using nonlinear regression by the software Prism 4.0.Based on the immobility of Daphnia magna due to the test chemical exposure for 48 hours, the EC50 value was observed to be 32.6 mg/l with the CI of 24.9 mg/l to 42.6 mg/l. Thus, based on EC50 value, test chemical considers to be toxic and classified in aquatic chronic category 3 as per the CLP classification criteria.

Thus on the basis of above all studies and effects observation, it is concluded that the test chemical consider to be toxic and classified in aquatic chronic category 3 as per the CLP classification criteria.

Toxicity to aquatic algae and cyanobacteria:

Based on the various predicted and experimental studies from different sources, studies were reviewed for the determination of the effects of test chemical and structurally and functionally similar read across chemicals on the growth rate inhibition of algae. The studies are as mentioned below:

 

The effect of test chemical on fresh water algae was studied by following OECD 201 guidelines using P subcapitata as test system. The mother culture was maintained in the same conditions of the test. From this preculture flask was taken and incubated for 3 days to attain the exponential growth. Cells from the exponential growth was taken for the main study. Based on the available data, main study was directly conducted with 5 test concentrations. The test substance was dissolved in the OECD medium and stirring was provided, to distribute chemical homogeniously, which was further analytically determined using UV visible spectrophotometer. Test concentrations selected for the study are 8, 12, 18, 27 and 40.5 mg/L separated with a factor of 1.5. Each test concentration was maintained in the triplicates along with control in 100 ml conical flask with 60 ml of test solution including test system. The algal cell count in each flask was 10000 cell/ ml at day 0. All the flasks were placed in an incubator and maintained for the period of 72 hours at a temperature of 21.8°C. The cell count was done using Neubauer chamber under microscope at regular 24 hours i.e., day0, day1 day 2 and day3 in all test vessels. The pH at the day 0 and day 3 was 7.5 and 8.3 respectively. The percent inhibition of cell growth at concentrations 8, 12, 18, 27, 40.5 was 8.5%, 15.58%, 17.13%, 28.55% and 65.55% respectively. All the test concentrations were analyzed for actual test substance, at 0 hours and 72 hours. which were not maintained within 80 -120% of the nominal concentrations, thus geometric mean was reported. The biomass of the control cultures have increased exponentially by a factor of 22.83 (specific growth rate 1.04 day-1) within the 72 hr period which is following the validity criteria of biomass in the control cultures of factor 16 (specific growth rate of 0.92 day-1) within the 72 hr test periods. The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hr tests) in the control cultures is9.52 %, thereby meeting the 35% validity criteria. The mean coefficient of variation of average specific growth rates during the whole test period in replicate control culture was found to be2.81 %and it must not be exceed 7% in the tests with Pseudokirchneriella subcapitata. 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 (ErC) were determined. thus EC50 was reported in geometric mean measured concentration of 0 hours and 72 hours. Based on outcomes of growth rates EC50 was reported to be 23.69mg/l (measured) and 35.65 mg/l (nominal). Thus chemical can be classified into aquatic chronic category 3 as per CLP classification criteria

Above data further supported by the second experimental study from peer reviewed journal. Principle of this study was to determine the effect of test chemical on the population growth rate inhibition of algae. Effects on the population growth of algae was tested according to the OECD guidelines for testing chemicals. Chlorella pyrenoidosa was used a test organism. Green algae were collected from H. Oldersma from TNO (Delft, The Netherlands). The algae were cultured in Miller’s solution using a 100 ml bottle, which was renewed (1:5) at least once a week. The algal cultures were incubated on top of a series of TL tubes and were shaken by a microplate shaker at 300 rpm. 5 Nominal concentrations and 1 control were used in the study. Effects were observed in the interval of 0, 6, 24, 48 and 72 hours. Based on the growth rate inhibition of green algae Chlorella pyrenoidosa due to the test chemical exposure for 72 hours, the EC50 value was determined to be 22 mg/l. Thus, based on the EC50 value, test chemical considers to be toxic and classified in aquatic chronic category 3 as per the CLP classification criteria.

 

Similar study was conducted to determine the effect of test chemical on the population growth rate inhibition of green algae. Pseudokirchneriella subcapitata was used a test organism. Test conducted under the closed system using triplicates. Algal growth medium was used in the study. Nominal concentrations were used to determine the effects. 15000 cells/ml was used and obtained from the laboratory.Test was performed at a temperature of 24°C. After the exposure period of 48 hours, 50 % median effective concentration were determined. Based on thepopulation growth rate inhibition of green algae Pseudokirchneriella subcapitata due to the test chemical exposure for 48 hours, the EC50 value was obtained to be at 14.19 mg/l.

In the fourth weight of evidence study from experimental source, the nature of test chemical when comes in contact with the green algae was determined. Test was conducted according to the OECD guideline 201. Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) was used as test organism. The stock solution (200 g/L) was prepared in acetone. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. 0, 12, 25, 50, 100 and 200 mg/L, respectively concentrations were used. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of test chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determined after an exposure period of 72 hrs. The median effective concentration (ErC50 value) of the test chemical on green algae was determined to be 59.2 mg/L with 95% CI of 38 mg/l to 92.4 mg/l on the basis of growth rate inhibition effects in a 72-hour study. Based on the ErC50 value, the chemical was considered likely to be hazardous to aquatic algae and can be considered to be classified in aquatic chronic 3 category as per the CLP classification criteria.

 

Thus, based on above all studies and effects observation, it was concluded that the test chemical considers to be toxic and classified in aquatic chronic category 3 as per the CLP classification criteria.

Toxicity to microorganisms:

Studies were reviewed and summarized based on the various results from different sources for the determination of the effects of test chemical and structurally and functionally similar read across chemicals on the growth rate inhibition of microorganisms. The studies are as mentioned below:

 

Principle of this study was to determine the effect of test chemical on the domestic activated sludge. Test conducted for 3 hours. The activated sludge collected from a municipal sewage treatment plant. The effective concentration (EC50) value for test material on domestic activated sludge in a 3 hours study were determined to be 100 mg/L based on effect observations on population growth rate. Thus, based on the EC50 value, test chemical considers to be toxic.

 

Above study further supported by the weight of evidence study from handbooks. Principle of this study was to determine the effect of test chemical on the population growth rate inhibition of microorganisms. Test conducted for the 16 hours. Based on the growth rate inhibition of Pseudomonas putida due to the test chemical exposure for 16 hours, the EC0 value was determined to be 29 mg/l.

 

Based on the above effects on the activated sludge and Pseudomonas putida, the effective concentration (EC50) value for test material on domestic activated sludge in a 3 hours study were determined to be 100 mg/L and based on the growth rate inhibition of Pseudomonas putida due to the test chemical exposure for 16 hours, the EC0 value was determined to be 29 mg/l.

 

Thus, based on above all studies and effects observation on fishes, invertebrates and algae, it was concluded that the test chemical considers to be toxic and classified in aquatic chronic category 3 as per the CLP classification criteria.