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Description of key information

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.

Additional information

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.