1,2-benzisothiazol-3(2H)-one 1,1-dioxide

Endpoint summary

Additional information

According to the fugacity model level III, the most likely environmental fate for this test chemical is soil (i.e. estimated to 69%). However, saccharin is not expected to be persistent in soil due to the estimated short half-life (30 days) (EPI suite version 4.1). Biodegradability was investigated for the read across compound sodium saccharin (CAS no. 128-44-9) in six different types of soils under anaerobic conditions. The half-life in soil was approximately 3 up to 12 days depending on soil type for sodium saccharin (Buerge et al., Environ. Sci. Technicol, 45, (2011) 615-621). The fast degradation in soil is consistent with the high elimination level observed in WWTPs (approx. 90%) for sodium saccharin (Buerge et al., 2011, Environ. Sci. Technicol, 45, 615-621). Henceforth, risk of chronic saccharin exposure terrestrial animals should be very low. There is also low risk for acute toxicity in microorganisms (Stolte et al., Environmntal International 60(2013); 123-127)

The Log Koc-value is experimentally determined to -1.353 at 25 ºC (UERL version 4.1). The tested chemical is therefore not expected to adsorb to sediments. Fugacity modelling shows that sediment is not an important environmental fate (less than 0% when estimated by EPI Suite version 4.1). There is also a high removal in sediment face of WWTPs (Subedia and Kannan, Environ. Sci. Technol. 2014, 48). There is low risk of exposure for benthic organisms, given the low Koc-value, low partion potential to sediment, and high removal in WWTPs.

According to environmental fate modelling, 31% of the test chemical is partioning into water. The half-life in water is estimated to be 15 days (less than the 40-day-threshold for persistence in water). Both environmental fate and persistence in water was estimated by EPI suite version 4.1. Saccharin is significantly removed from WWTPs (90% removal efficiency) in US. Similar WWTP-results have been reported both from Germany and China. The removal frequency were high both in the sludge- and water face of the WWTP process (Subedia and Kannan, Environ. Sci. Technol. 2014, 48). Volatilization from water surfaces is not expected based upon the test chemicals estimated Henry's Law constant (EPI suite version 4.1). Hence, the current compound is expected to be rapidly degraded in water.

Following is the summary of the endpoints presented in this section:

Stability

Phototransformation in air

The atmospheric oxidation half-life of 1,2-benzisothiazol-3(2H)-one 1,1-dioxide was estimated using the level III multimedia model. It was estimated that the substance is persistent in air medium as the half life period of 1,2-benzisothiazol-3(2H)-one 1,1-dioxide in air is 2.7 days. This indicates that 1,2-benzisothiazol-3(2H)-one 1,1-dioxide is not photo transformed in air.

OVERALL OH Rate Constant = 0.0000000000059 cm3/molecule-sec.

Hydrolysis

The Hydrolysis rate constant of 1,2-benzisothiazol-3(2H)-one 1,1-dioxide is estimated to be 0.00000000000588 cm3/molecule-sec. at half life of 21.828 Hrs.The estimated half life of the substance indicates that the substance is moderately hydrolysable.

Phototransformation in water

No experimental data available. As this study is not a standard information requirement in REACH and there is no indication from the CSA on the need to investigate further the fate and behaviour of the substance (Annex X requirement), no further testing is considered necessary.

Phototransformation in soil

No experimental data available. As this study is not a standard information requirement in REACH and there is no indication from the CSA on the need to investigate further the fate and behaviour of the substance (Annex X requirement), no further testing is considered necessary.

Biodegradation

Biodegradation in water:

The ready biodegradability study results (UERL) on the close read-across (sodium saccharin) indicates that the substance is moderately biodegradable. Further this is supported by the ultimate biodegradation estimate in the Biowin model (EPI suite version 4.1) shows that the current compound is moderately biodegradable (biowin 2=0.6, biowin 3=2.8, biowin<0.5).

The summary of the results are presented below

Sr.No	Test Type	Percentage Degradation	Half - Life	Parameter	Sources
1	Ready biodegradability	50% degradation	15 days	Half-life	Predicted data from PBT profiler
2	Ready biodegradability	58.2714 % degradation	-	O2 consumption	Predicted data from QSAR

 

By applying weight of evidence approach to the target chemical 1,2-benzisothiazol-3(2H)-one 1,1-dioxide it was found that the degradation percentage of 1,2-benzisothiazol-3(2H)-one 1,1-dioxide in water medium is 50 to 58%.This result in ready biodegradability of the chemical. 

 

Biodegradation in water and sediment

No. of studies reviewed for Biodegradation in water and sediment from reliable sources having Klimisch rating 2.

The summary of the results are presented below

Sr.No	Endpoint	Percentage Degradation	Half - Life	Parameter	Sources
1.	Ready biodegradability	90% degradation	Sediment-7 days	Test material analysis	Experimental data from Environmental Science & Technology;2014
2.	Ready biodegradability	50% degradation	Water-15 days   Sediment-140 days	Half-life	Predicted data from PBT profiler
3.	Ready biodegradability	50% degradation	Water-15 days   Sediment-135 days	O2 consumption	Predicted data from EPI suite

 

By applying weight of evidence approach to the target chemical 1,2-benzisothiazol-3(2H)-one 1,1-dioxide it was found that the degradation percentage of 1,2-benzisothiazol-3(2H)-one 1,1-dioxide in water and sediment medium in the range 50 to 90%.This result in ready biodegradability of the chemical. 

Biodegradation in soil

No. of studies reviewed for Biodegradation in soil from reliable sources having Klimisch rating 2.

 

The summary of the results are presented below

  

Sr.No	Endpoint	Half life	Parameter	Result	Sources
1	Biodegradation in soil	30 days	Half-life	Not persistent (Readily biodegradable)	Predicted data from PBT profiler and EPI suite
2	Biodegradation in soil	30.2 days	DT50(Dissipation time)	Not persistent (Readily biodegradable)	Predicted data from QSAR

 

By applying weight of evidence approach to the target chemical,thedegradation of parent compound 1,2-benzisothiazol-3(2H)-one 1,1-dioxide in soil was estimated as 50 percent in 30 to 30.2 days whichdoes not exceeds the EPA criteria of >= 2 months (and <= 6 months). Therefore, 1,2-benzisothiazol-3(2H)-one 1,1-dioxide is estimated not to be persistent in the soil environment.

 

 

Bioaccumulation

No. of studies of target substance 1,2-benzisothiazol-3(2H)-one 1,1-dioxide reviewed for bioaccumulation from reliable sources having Klimisch rating 2 and 4.

The summary of the results are presented below

Sr.No	Endpoint	Effect values	Interpretation of results	Species	Sources
1	BCF	3.2	Non -bioaccumulative	Fish	Predicted data from PBT
2	BCF	3.162	Non -bioaccumulative	Fish	Predicted data from EPI Suite
3	BCF	1.58-2.1	Non -bioaccumulative	Aquatic organisms	Experimental data from Handbook of Chemical Property Estimation Methods
4	BCF	6.38	Non -bioaccumulative	Fish	Predicted data from QSAR

 

By applying weight of evidence approach to the target substance 1,2-benzisothiazol-3(2H)-one 1,1-dioxide,the endpoint value of bioaccumulation was found to vary between BCF = 1.58 to 6.38 in aquatic organisms /fish.Thus it is concluded that the test substance 1,2-benzisothiazol-3(2H)-one 1,1-dioxide is not expected to bioaccumulate in the food chain because it does not exceed the BCF criteria.

Transport and distribution

Adsorption/Desorption

Soil Adsorption Coefficient i.e Koc value of 1,2-benzisothiazol-3(2H)-one 1,1-dioxide was estimated as 10 L/kg by means of MCI method. This indicates that 1,2-benzisothiazol-3(2H)-one 1,1-dioxide will have negligible tendency of sorption to soil and sediment and therefore have rapid migration potential to groundwater.

Henry's Law constant

Henry's Law states that at a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.Henry’s law constant of1,2-benzisothiazol-3(2H)-one 1,1-dioxidewas estimated to be 0.000125 Pa m³/mol at 25 degC.