Merbromin

Endpoint summary

Description of key information

Short term toxicity to aquatic invertebrate:

Aim of this study was to assess the short term toxicity of test material to aquatic invertebrates daphnia magna. Study was performed according to the OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) in a static system for the total exposure period of 48 hrs.

 The stock solution 50 mg/l was prepared by dissolving dark orange granules in reconstituted water. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with reconstituted test water.0.05 , 0.10 , 0.20 , 0.40 , 0.80 mg/lconcentrations were used in the study. Effects on immobilisation were observed for 48 hours. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0.

 The median effective concentration (EC50) for the test substance , in Daphnia magna was determined to be 0.18 mg/L on the basis of mobility inhibition effects in a 48 hour study. Based on the EC50 value, substance is likely to be highly hazardous to aquatic invertebrate and can be classified as aquatic acute/ chronic 1 category as per the CLP classification criteria.

Toxicity to aquatic algae and cyanobacteria:

The study was designed to assess 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).

Test was carried out in 100mL conical flasks which were carefully autoclaved and sterilized. The test solution in each of these test vessels was kept constant which is 60 ml so that a sufficient amount of head space was left.The test item  was prepared by adding 0.278 mg of test item in 250 ml of BBM to get the final concentration of 1.112 mg/L. This stock solution was kept for stirring for 01 minutes to obtain a homogenous solution for the experiment. The test concentrations were chosen according to the available data of the test item. The concentrations chosen were set up to the water solubility limit.

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.

Algal growth was calculated daily by counting the cells microscopically with the help of haemocytometer. For microscopic observations the cultures were observed daily with the help of a microscope to verify a normal and healthy appearance of the algal culture and also to observe any abnormal appearance of the algae (as may be caused by the exposure of the test item). Apart from this, the cell count of each test vessel was also noted with the help of a microscope and haemocytometer. By spectrophotometer the absorbance values of each test vessel and control vessel was noted at 680nm.The BBM was taken as blank for both control and test vessels. The absorbance value of each vessel was in line with the average specific growth rate.

As per OECD 201, the biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72 hr test period. This corresponds to a specific growth rate of 0.92 per day. Thus, the observed specific growth rate in the control cultures during the experiment was 0.358 per day. Secondly the mean coefficient of variation for section by section specific growth rates (days 0-1, 1-2 & 2-3, for 72 hr tests) in the control cultures must not exceed 35%. Thus, the observed mean coefficient of variation in the control cultures during the experiment was 33.42%. Thirdly the coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 10%. Thus, the observed coefficient of variation of average specific growth rates during the experiment in control cultures was 8.26%. Hence, the test is considered valid as per OECD guideline, 201

After 72 hours of exposure to test item to various nominal test concentrations, EC50 was determine to be 1.095 mg/l graphically and through probit analysis. Based on the EC50, it can be concluded that the chemical was toxic and can be consider to be classified as aquatic chronic 2 as per the CLP classification criteria.

Additional information

Short term toxicity to aquatic invertebrate:

Aim of this study was to assess the short term toxicity of test material to aquatic invertebrates daphnia magna. Study was performed according to the OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) in a static system for the total exposure period of 48 hrs.

 The stock solution 50 mg/l was prepared by dissolving dark orange granules in reconstituted water. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with reconstituted test water.0.05 , 0.10 , 0.20 , 0.40 , 0.80 mg/lconcentrations were used in the study. Effects on immobilisation were observed for 48 hours. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0.

 The median effective concentration (EC50) for the test substance , in Daphnia magna was determined to be 0.18 mg/L on the basis of mobility inhibition effects in a 48 hour study. Based on the EC50 value, substance is likely to be highly hazardous to aquatic invertebrate and can be classified as aquatic acute/ chronic 1 category as per the CLP classification criteria.

Toxicity to aquatic algae and cyanobacteria:

Two experimental studies were performed to evaluate short term toxicity of test material on aquatic algae .The study was designed to assess 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).

Test was carried out in 100mL conical flasks which were carefully autoclaved and sterilized. The test solution in each of these test vessels was kept constant which is 60 ml so that a sufficient amount of head space was left.The test item  was prepared by adding 0.278 mg of test item in 250 ml of BBM to get the final concentration of 1.112 mg/L. This stock solution was kept for stirring for 01 minutes to obtain a homogenous solution for the experiment. The test concentrations were chosen according to the available data of the test item. The concentrations chosen were set up to the water solubility limit.

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.

Algal growth was calculated daily by counting the cells microscopically with the help of haemocytometer. For microscopic observations the cultures were observed daily with the help of a microscope to verify a normal and healthy appearance of the algal culture and also to observe any abnormal appearance of the algae (as may be caused by the exposure of the test item). Apart from this, the cell count of each test vessel was also noted with the help of a microscope and haemocytometer. By spectrophotometer the absorbance values of each test vessel and control vessel was noted at 680nm.The BBM was taken as blank for both control and test vessels. The absorbance value of each vessel was in line with the average specific growth rate.

As per OECD 201, the biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72 hr test period. This corresponds to a specific growth rate of 0.92 per day. Thus, the observed specific growth rate in the control cultures during the experiment was 0.358 per day. Secondly the mean coefficient of variation for section by section specific growth rates (days 0-1, 1-2 & 2-3, for 72 hr tests) in the control cultures must not exceed 35%. Thus, the observed mean coefficient of variation in the control cultures during the experiment was 33.42%. Thirdly the coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 10%. Thus, the observed coefficient of variation of average specific growth rates during the experiment in control cultures was 8.26%. Hence, the test is considered valid as per OECD guideline, 201

After 72 hours of exposure to test item to various nominal test concentrations, EC50 was determine to be 1.095 mg/l graphically and through probit analysis. Based on the EC50, it can be concluded that the chemical was toxic and can be consider to be classified as aquatic chronic 2 as per the CLP classification criteria.

In another study ,Aim of this study was to evaluate the nature of chemical test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201.The stock solution 100 mg/l was prepared by dissolving dark orange granule in OECD growth medium . Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture.0.5 , 1.0 , 2.0 , 4.0 , 8.0 , 16 mg/lconcentration were used.

With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs.

The median effective concentration (ErC50) for the test substance in algae was determined to be 12.1 mg/L on the basis of growth rate inhibition effects in a 72 hour study. Based on the ErC50 value, which indicates that the substance is likely to be hazardous to aquatic algae and can be classified as aquaticfirst chronic 3 category as per the CLP classification criteria.

The test substance has varied toxic effects on two different algae, we would classify the test substance as aquatic chronic 2 based on the effect concentration of first study.