Dimethyl sulphone

Endpoint summary

Description of key information

Short term toxicity to fish:

Study was designed to assess the toxic effects of the test compound on the Zebra fish (Denio rerio). Bowl aquaria containing 2 liters of potable water (passed through reverse osmosis system) were loaded with 8 fishes each. A static procedure was used for the study and it was conducted in compliance with the OECD guideline 203 on Zebra fish (Danio rerio). The test substance was soluble in water. Therefore, the test solution was prepared by dissolving 400 mg of the test substance in 4 liters of potable water (passed through reverse osmosis system) with 1 hr.continuous stirring for achieving test concentrations of 100 mg/L, respectively. The nominal concentration selected for the experiment were 100 mg/L and test fish were exposed to these concentration for 96 hours. The median lethal concentration (LC50) for test chemical on Danio rerio in a 96 hours study on the basis of mortality effect was determine to be >100 mg/L. Based on this LC50 value and according to CLP criteria for aquatic classification of the substance, it is concluded that the substance, does not exhibit short term toxicity to aquatic fish (Danio rerio).

LC0 (96 hours) (highest loading at which no mortality was observed) = 100 mg/L

LC50 (96 hours) Experimental = >100 mg/L

Short term toxicity to aquatic invertebrate:

Determination of the inhibition of the mobility of daphnids was carried out with the substance according to OECD Guideline 202. A limit test at sample concentration of 100 mg/L was performed. Effects on immobilisation were observed for 48 hours. The test was performed under static conditions in a fresh water system at a temperature of 20 °C± 1 °C. EC50 was calculated. After the exposure of test chemical with daphnia magna for 48 hrs, only 5% inhibition were observed at 100 mg/l. Thus EC50 was consider to be > 100 mg/l on the basis of mobility inhibition effects in a 48 hours of study. Based on this EC50 value and after comparing with CLP criteria for aquatic classification of the substance it is concluded that the substance does not exhibit short term toxicity to aquatic invertebrate (Daphnia Magna) and thus not classified as per the CLP classification criteria.

Toxicity to aquatic algae and cyanobacteria:

The freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance. Test conducted in accordance to OECD Guideline 201. The solution 100 mg/L was prepared by dissolving white powder in OECD growth medium. A limit test at sample concentration of 100 mg/L was performed. Effects on the growth rate of the organism were studied. The test was performed under static conditions in a static fresh water system at a temperature of 23± 2°C. Initial cell density of test organism used was 5x1000 cells/ml. Determination of cell counting involve the use of electronic particle counter. The median effective concentration (EC50) for the test substance in a freshwater algae Desmodesmus subspicatus was determined to be >100 mg/L on the basis of effects on growth rate in a 72 hour study. After the exposure period of 72 hrs, only 0.5 % inhibition were observed on algae. Thus on the basis of this EC50 value and according to the CLP Criteria for aquatic classification of the substance, it is concluded that test chemical does not exhibit toxicity to aquatic algae.

Toxicity to microorganisms:

2nd study: The median effective concentration (EC50) value of test chemical in tetrahymena pyriformis was observed to be 32000 mg/L on the basis of population growth rate effect in a 24 hours of exposure.

3rd study: The effect concentration (EC50) value of test chemical on microorganism (Bacteria sp.) in a 17 hrs study was observed at a dose concentration of > 10000 mg/L.

Additional information

Summarized result for the toxicity of test chemical were studied for the determination of effect of test chemical on the mortality, mobility and growth rate inhibition of fish, invertebrates, algae and microorganisms. All the studies mention below:

Short term toxicity to fish:

Based on the effects observation on the mortality of fish by the chemical exposure, studies were reviewed from various experimental sources for test chemical were studied and mention as below:

In the first key study from experimental report, study was designed to assess the toxic effects of the test compound on the Zebra fish (Denio rerio). Bowl aquaria containing 2 liters of potable water (passed through reverse osmosis system) were loaded with 8 fishes each. A static procedure was used for the study and it was conducted in compliance with the OECD guideline 203 on Zebra fish (Danio rerio). The test substance was soluble in water. Therefore, the test solution was prepared by dissolving 400 mg of the test substance in 4 liters of potable water (passed through reverse osmosis system) with 1 hr.continuous stirring for achieving test concentrations of 100 mg/L, respectively. The nominal concentration selected for the experiment were 100 mg/L and test fish were exposed to these concentration for 96 hours. The median lethal concentration (LC50) for test chemical on Danio rerio in a 96 hours study on the basis of mortality effect was determine to be >100 mg/L. Based on this LC50 value and according to CLP criteria for aquatic classification of the substance, it is concluded that the substance, does not exhibit short term toxicity to aquatic fish (Danio rerio).

LC0 (96 hours) (highest loading at which no mortality was observed) = 100 mg/L

LC50 (96 hours) Experimental = >100 mg/L

 

First study was supported by the second study from secondary source. A marine toxicity test was conducted to determine the acute effect of test chemical on sheepshead minnows (Cyprinodon variegatus) in a static system for 96 hours study. The test was conducted in 3.8 liter covered glass jars each of which contained a final volume of 3 L. There were no aeration. Based on the results of range finding test with mysid shrimp, fish were definitively tested at maximum concentration of 1000 mg/L. Therefore 1000 mg/l test concentration used in study. This test concentration was prepared by adding an appropriately weighed amount of test chemical directly to seawater in each test jar. Control jars contained only seawater. Test chemical was not toxic to sheepshead minnows in a test concentration of 1,000 mg/l. After 96 hours of exposure, there was no mortality in the 1,000 mg/l test concentration and also in the control. Fish in both the control and test concentration appeared to be in good condition throughout the test. Therefore, the lethal concentration (LC0) of test chemical on Cyprinodon variegatus was considered to be 1000 mg/L.

 

Thus on the basis of above effects on the mortality of fish, it was concluded that the chemical was nontoxic and not classified as per the CLP classification criteria.

 

Short term toxicity to aquatic invertebrate:

Based on the effects observation on the mobility of aquatic invertebrate by the chemical exposure, studies were reviewed from various experimental sources for test chemical were studied and mention as below:

In the first key study from experimental report determination of the inhibition of the mobility of daphnids was carried out with the substance according to OECD Guideline 202. A limit test at sample concentration of 100 mg/L was performed. Effects on immobilisation were observed for 48 hours. The test was performed under static conditions in a fresh water system at a temperature of 20 °C± 1 °C. EC50 was calculated. After the exposure of test chemical with daphnia magna for 48 hrs, only 5% inhibition were observed at 100 mg/l. Thus EC50 was consider to be > 100 mg/l on the basis of mobility inhibition effects in a 48 hours of study. Based on this EC50 value and after comparing with CLP criteria for aquatic classification of the substance it is concluded that the substance does not exhibit short term toxicity to aquatic invertebrate (Daphnia Magna) and thus not classified as per the CLP classification criteria.

First experimental study was supported by the second study from secondary source. A 96 hr static toxicity test was conducted to determine the toxic effect of test chemical on mysid shrimp (Mysidopsis bahia). The test was conducted in 1-L uncovered glass beakers, each of which contained 900ml of test chemical and control seawater. There was no aeration. Dissolved oxygen (DO) concentrations were >97% of saturation at initiation of the test. Shrimp were not fed during the test. Based on the results of range finding study, shrimp were tested at nominal concentration of 1000ppm. The test concentration was prepared by adding 0.9184 grams of test chemical in directly to seawater. Exposure to test chemical did not appear to adversely affect mysid shrimp. After 72 hours of exposure, no mortality had occurred in 1,000 ppm and control. After 96 hours of exposure, mortality was 10% among mysids exposed to 1,000 ppm and among control mysids 5% mortality were observed. Therefore, the LC10 value for test chemical is considered to be 1000 mg/l on mysid shrimp (Mysidopsis bahia). Based on the mortality effect, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

 

Thus based on the both studies from experimental report and secondary source, it was concluded that the chemical was nontoxic and not classified as per the CLP classification criteria.

 

Toxicity to aquatic algae and cyanobacteria:

Based on the effects observation on growth rate inhibition of algae by the chemical exposure, studies were reviewed from various experimental sources for test chemical were studied and mention as below:

In the first experimental report toxicity were studied. The freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance. Test conducted in accordance to OECD Guideline 201. The solution 100 mg/L was prepared by dissolving white powder in OECD growth medium. A limit test at sample concentration of 100 mg/L was performed. Effects on the growth rate of the organism were studied. The test was performed under static conditions in a static fresh water system at a temperature of 23± 2°C. Initial cell density of test organism used was 5x1000 cells/ml. Determination of cell counting involve the use of electronic particle counter. The median effective concentration (EC50) for the test substance in a freshwater algae Desmodesmus subspicatus was determined to be >100 mg/L on the basis of effects on growth rate in a 72 hour study. After the exposure period of 72 hrs, only 0.5 % inhibition were observed on algae. Thus on the basis of this EC50 value and according to the CLP Criteria for aquatic classification of the substance, it is concluded that test chemical does not exhibit toxicity to aquatic algae.

 

Similarly in the second study from secondary sources (1991) a phytotoxicity test was performed to determine the effect of test chemical on the marine alga Skeletonema costatum. Cultures were incubated at 20 degrees Celsius (°C) under approximately 2,000 lux illumination. Culture were exposed to 500 & 1000 mg/l (ppm) concentration of test chemical. Concentrations for the definitive test were based on the results of a 96-hour range-finding test. Concentrations of test chemical ≤ 1000 mg/L did not appear to adversely affect the growth of Skeletonema costatum. After 96 h of exposure, increase of in vivo chlorophyll a was 8% in cultures exposed to 500ppm and 14% in those exposed to 1000 mg/l. Cell numbers in cultures exposed to 500 mg/l increased 4% while cultures exposed 1000 mg/l were similar to the control. Thus, the no observed effect concentration (NOEC) of test chemical on the marine alga Skeletonema costatum on a growth rate effect was considered to be ≤ 1000 mg/L in a 96 hour study.

 

Thus based on the both studies experimental data from report and secondary source, it was concluded that the chemical was nontoxic and not classified as per the CLP classification criteria.

 

Toxicity to microorganisms:

Based on the effect observation of read across chemical selected on the basis of functional similarity with the test chemical on the growth of microorganisms, studies have been reviewed and summarized as mention below:

 

In this study from peer reviewed journal, a test was developed using Tetrahymena pyriformis in order to determine the toxicity of test chemical. Pre-cultured T. pyriformis was exposed for 24 h at 30°C to various concentrations, and the number of T. pyriformis surviving were then counted. The concentration of the chemical, at which the proliferation of T. pyriformis was restricted to one-half of the blank test (EC50), was determined. The median effective concentration (EC50) value of test chemical in tetrahymena pyriformis was observed to be 32000 mg/L on the basis of population growth rate effect in a 24 hours of exposure. Thus, it can be concluded that the test substance does not exhibit any toxicity effect to microorganism (tetrahymena pyriformis).

 

Similarly in the next study from peer reviewed journal toxicity on the bacterial growth were observed for 17 hrs. Short term toxicity of chemical was studied on the growth of bacteria. The effect concentration (EC50) value of test chemical on microorganism (Bacteria sp.) in a 17 hrs study was observed at a dose concentration of > 10000 mg/L.

Thus based on the overall effect, it was concluded that the chemical was nontoxic and not classified as per the CLP classification criteria.