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Description of key information

Stability:

Hydrolysis:

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be ranges from 5 to 5.5  yr, at pH range 7 and 200 days at pH 8 by second order hydrolysis rate constand and 38 days at pH 7 by pseudo-first order hydrolysis rate constant  at 25 oC temperature. Thus, based on this half-life value, it can be concluded that the test chemical not hydrolysable in water.

Biodegradation:

Biodegradation in water:

The test chemical undergoes 53.60 % biodegradation after 28 days in the test condition. Thus, the test item can be considered as ultimate inherently biodegradable.

Biodegradation in water and sediments:

Estimation Programs Interface (EPI Suite, 2018) prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment,  34.7  % of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of test chemical in water is estimated to be 15 days ( 360  hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of test chemical in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.078 %), indicates that test chemical is not persistent in sediment.

Biodegradation in Soil:

The half- life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2018). If released into the environment, 64.4 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is low.

Bioaccumulation:

Bioaccumulation: aquatic/sediments:

Using BCFBAF Program (v3.00) model of EPI suite (2018) the estimated bio concentration factor (BCF) for test chemical is 3.162 L/kg wet-wt at 25 deg. c which does not exceed the bioconcentration threshold of 2000. Therefore it is concluded that test chemical is non-bioaccumulative in food chain.

Transport and distribution:

Adsorption/desorption:

The Adsorption Coefficient of test chemical was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was determined to be 3.307 dimensionless at 25°C. Thus based on the result it is concluded that the test substance has a moderate sorption to soil and sediment and therefore has slow migration potential to ground water.

Additional information

Stability:

Hydrolysis:

Data available for the test chemical has been reviewed from authoritative database (HSDB, 2018)to determine the half-life of hydrolysis as a function of pH. The studies are as mentioned below:

In first weight of evidence study the base catalyzed second order hydrolysis rate constant of test chemical was determined using a structure estimation method. The second order hydrolysis rate constant is determined to be 4.2 × 10-2 L/mol-sec with a corresponding half lives of 5.5 years and 200 days at pH 7 and 8, respectively. Based on the half-life values, it is concluded that the test chemical is naot hydrolysable.

In another study the half-life of the test chemical was determined using an estimated pseudo-first order hydrolysis rate constant of 0.000000 21/sec. The half-life of test chemical was determined to be 38 days at pH 7 and a temperature of 25°C, respectively. Based on the half-life values, it is concluded that the chemical is not hydrolysable.

In last study the base catalyzed second order hydrolysis rate constant and half life of hydrolysis of test chemical was determined using a structure estimation method. The second order hydrolysis rate constant is determined to be 4.0 × 10-2L/mol-sec with a corresponding half lives of 5 years and 200 days at pH 7 and 8, respectively. Based on the half-life values, it is concluded that the test chemical is not hydrolysable.

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be ranges from 5 to 5.5 yr, at pH range 7 and 200 days at pH 8 by second order hydrolysis rate constant and 38 days at pH 7 by pseudo-first order hydrolysis rate constant at 25 oC temperature. Thus, based on this half-life value, it can be concluded that the test chemical not hydrolysable in water.

Biodegradation:

Biodegradation in water:

Various experimental key and supporting studies for the target compound 1,2-Benzisothiazol-3(2H)-one 1,1-dioxide, sodium salt (CAS No. 128-44-9) were reviewed for the biodegradation end point which are summarized as below

 

In first experimental study the 28-days Manometric respirometry test was performed following the OECD guideline 301F to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20± 1°C. Mixture of domestic waste water, surface soil and soil samples was used as a test inoculum for the study. This inoculum was collected and was mixed to get diluted suspension. The inoculum was kept aerobic until being used for experiment by supplying organic and inorganic sources required by micro flora to sustain at controlled laboratory conditions.  This gave the bacterial count as 10E7to 10E8 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. OECD mineral medium was used for the study. The test system included control, test item and reference item. The concentration of test and reference item ( Sodium Benzoate) chosen for both the study was 100 mg/L, while that of inoculum was 10 ml/L. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % Degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (Sodium Benzoate) was also calculated using BOD & ThOD and was determined to be 75.20 %. The mean BOD value (mg O2/l) in control on 28th day was 1.252 mg O2/l, thereby fulfilling the control validity criteria (i.e., The oxygen consumption of the inoculum blank is normally 20-30 mg O2/l and should not be greater than 60 mg/l in 28 days). Degradation of Sodium Benzoate exceeds 65.65 %after 7 days and 69.79 % after 14 days. The activity of the inoculums is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 0.648 mgO2sup>/mg. ThOD was calculated as 1.209 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 53.60 %.Based on the results, the test item, under the test conditions, was considered to be ulimate inherently biodegradable at 20 ± 1°C over a period of 28 days.

Another experimental study was performed in this study test was performed following the OECD guideline 301 D to determine the ready biodegradability of the test item. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used for this study. 1 polyseed capsule were added in 500 ml D.I water and then stirred for 1 hour for proper mixing and functioning of inoculum. This gave the bacterial count as 10E7 to 10E8 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml/L. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 73.49  %. Degradation of Sodium Benzoate exceeds 39.15 % on 7 days & 61.44 on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.12 mgO2/mg. ThOD was calculated as 1.17 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 96.55 %. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

Last experimental study was reviewed from peer reviewed journal(Jitendra R. Harjani, et. al; 2009) in this study theBiodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test substance. The study was performed according to OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test).This method allows the evaluation of the ultimate aerobic biodegradability of an organic compound in an aqueous medium at a given concentration of microorganisms by analysis of inorganic carbon. Activated sludge was used as a test inoculums collected from an activated sludge treatment plant. Initial test substance conc. used in the study was 40 mg/l. The test chemical as the sole source of carbon and energy was added at a concentration of 40 mg/l to a mineral salt medium. These solutions were inoculated with activated sludge, washed and aerated prior to use and incubated in sealed vessels with a headspace of air. Biodegradation (mineralization to carbon dioxide) was determined by measuring the net increase in the total organic carbon (TOC) levels over time compared with unamended blanks. The test ran for 28 days. The extent of biodegradation was expressed as a percentage of the theoretical amount of inorganic carbon (ThIC) based on the amount of test compound. Sodiumn-dodecyl sulfate (SDS) was used as a reference substance for the study. Test chemical undergoes 41% degradation by TOC removal parameter in 28 days. It is noted that chemical has reached its highest level of biodegradability within 14 days of incubation, which has been associated with very high rates of biodegradation of the saccharin anion. Thus, based on percentage degradation, test chemical is considered to be inherently biodegradable in nature.

On the basis of above results from experimental studies for target chemical1,2-Benzisothiazol-3(2H)-one 1,1-dioxide, sodium salt(from study report and peer reviewed journal), it can be concluded that the test substance1,2-Benzisothiazol-3(2H)-one 1,1-dioxide, sodium saltcan be expected to beinherentlybiodegradable in nature.

Biodegradation in water and sediments:

Estimation Programs Interface (EPI Suite, 2018) prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment,  34.7  % of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of test chemical in water is estimated to be 15 days ( 360  hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of test chemical in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.078 %), indicates that test chemical is not persistent in sediment.

Biodegradation in Soil:

The half- life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2018). If released into the environment, 64.4 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is low.

Bioaccumulation:

Bioaccumulation: aquatic/sediments:

Predicted data study for target chemical and experimental studies for its read across chemical have been reviewed from different sources and their results are summarized below.

The first study was predicted data study in this BCFBAF Program (v3.00) model of EPI suite (2018) was used to estimate bio concentration factor (BCF) for test chemical and estimated BCF value was 3.162 L/kg wet-wt at 25 deg. c which does not exceed the bioconcentration threshold of 2000. Therefore it is concluded that test chemical is non bioaccumulative in food chain.

Next study was experimental study reviewed from authoritative database (HSDB, 2018) in this study the BCF value of test chemical was estimated to be 3 dimensionless by using log Kow of 0.91 and regression derived equation and it is far less than 2000 criteria so it is concluded that test chemical is non bioaccumulative.

Last study was also experimental study from authoritative database (HSDB, 2018) in this the BCF value The BCF value of test chemical was estimated is 6.0 dimensionless by using log Kow of 1.88 and regression derived equation and it is far less than 2000 criteria so it is concluded that test chemical is non bioaccumulative.

By considering results of all the studies mentioned above it can be concluded that test chemical is non bioaccumulative in food chain.

Transport and distribution:

Adsorption/desorption:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 . The reference substances were chosen according to functional similarity with the test substance and calibration graph prepared.

The reference substances were 4-chloroaniline, 4-methylaniline, N methylaniline, 2-Nitrophenol, Nitrobenzene, 4-Nitrobenzamide, N,N-dimethylbenzamide, N-methylbenzamide, Benzamide, phenanthrene having Kocvalue ranging from 1.239 to 4.09. .The Log Koc value was determined to be 3.307 dimensionless at 25°C.

 

Thus based on the result it is concluded that the test substance has a moderate sorption to soil and sediment and therefore has slow migration potential to ground water.