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

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Qualifier:

according to guideline

Guideline:

other:

Principles of method if other than guideline:

Groups of mice (n=4) were exposed topically on the dorsum of both ears to 25 l of various concentrations of the test chemicals, or to the same volume of the relevant vehicle alone, daily for 3 consecutive days. Five days following initiation of exposure all mice were injected via the tail vein with 250 l of phosphate buffered saline (PBS) containing 20 Ci of [3H] methyl thymidine. Five hours later the mice were sacrificed and the draining auricular lymph nodes excised and pooled for each experimental group. Single cell suspensions of LNC were prepared by mechanical disaggregation through 200-mesh stainless steel gauze. Pooled LNC were washed twice with PBS and precipitated in 5% trichloroacetic acid (TCA) at 4°C overnight. Pellets were then resuspended in 1 ml of TCA and transferred to 10 ml of scintillation fluid (Optiphase ‘Hisafe 3’, Wallac, Turku, Finland). The incorporation of 3H-TdR was measured by -scintillation counting as disintegrations per minute (dpm) per node for each experimental group. In each case a stimulation index (SI) relative to the concurrent vehicle-treated control was
derived; an SI of 3 or greater being indicative of a chemical possessing the potential to cause contact sensitization

GLP compliance:

not specified

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

Young adult (8–12 weeks old) CBA/Ca strain female mice (Harlan Seralab, Oxon, UK) were used throughout these studies. Animals were housed four per cage on flushing metal racks. Food (SDS PCD pelleted diet; Special Diets Services, Witham, Essex, UK) and water were available ad libitum.

Route:

intradermal and epicutaneous

Vehicle:

DMSO

Concentration / amount:

0, 25, 50 and 75 %

Concentration / amount:

0, 25, 50 and 75 %

Vehicle:

dimethyl sulphoxide

Concentration:

25 µl

No. of animals per dose:

total: 16
0 %: 4 female
25 %: 4 female
50 %: 4 female
70 %: 4 female

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: 536 dpm/node to 803 dpm/node

The maximal stimulation indices for saccharin was 1.50, at a test concentration of 50%. Saccharin, which failed to stimulate a positive response at any concentration tested, EC3 values of 50 and > 75 %, respectively, were assigned, according to the maximum concentrations tested in each case.

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The maximal stimulation indices for saccharin was 1.50, at a test concentration of 50%. Saccharin, which failed to stimulate a positive response at any concentration tested, EC3 values of 50 and > 75 %, respectively, were assigned, according to the maximum concentrations tested in each case.

Executive summary:

The maximal stimulation indices for saccharin was 1.50, at a test concentration of 50%. Saccharin, which failed to stimulate a positive response at any concentration tested, EC3 values of 50 and > 75 %, respectively, were assigned, according to the maximum concentrations tested in each case.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Weight of evidence summary for skin sensitization

In different studies, saccharin has been investigated for skin sensitizing effects. Often are the studies based on in vivo experiments in rodents, i.e. most commonly in mice or rats.

In a Mouse local lymphnode assay (LLNA) conducted by Warbrick et al (2001), Groups of mice (n=4) were exposed topically on the dorsum of both ears to 25 l of various concentrations of the test chemicals, or to the same volume of the relevant vehicle alone, daily for 3 consecutive days. Five days following initiation of exposure all mice were injected via the tail vein with 250 l of phosphate buffered saline (PBS) containing 20 Ci of [3H] methyl thymidine. Five hours later the mice were sacrificed and the draining auricular lymph nodes excised and pooled for each experimental group. Single cell suspensions of LNC were prepared by mechanical disaggregation through 200-mesh stainless steel gauze. Pooled LNC were washed twice with PBS and precipitated in 5% trichloroacetic acid (TCA) at 4°C overnight. Pellets were then resuspended in 1 ml of TCA and transferred to 10 ml of scintillation fluid (Optiphase ‘Hisafe 3’, Wallac, Turku, Finland). The incorporation of 3H-TdR was measured by -scintillation counting as disintegrations per minute (dpm) per node for each experimental group. In each case a stimulation index (SI) relative to the concurrent vehicle-treated control was derived; an SI of 3 or greater being indicative of a chemical possessing the potential to cause contact sensitization.

The maximal stimulation indices for saccharin were 1.50, at a test concentration of 50%. Saccharin, which failed to stimulate a positive response at any concentration tested, EC3 values of 50 and > 75 %, respectively, were assigned, according to the maximum concentrations tested in each case. Thus based on this it can be concluded that saccharin does not induce the sensitization to skins of mice.

In another study by Patlewicz et al (2008) Saccharin is nonsensitizer by prediction generated from TIMES-SS/toolbox protein binding - nucleophilic heterocycle ring opening (acry transfer). Also from QSAR prediction it can be concluded that sodium saccharin is non sensitizing to skin.

Thus from all above studies it can be concluded that saccharin is not classified as the skin sensitizer as per the new CLP regulation.

Migrated from Short description of key information:
Saccharin was predicted as not being sensitizing to the skin of mouse.

Justification for selection of skin sensitisation endpoint:
The maximal stimulation indices for saccharin was 1.50, at a test concentration of 50%. Saccharin, which failed to stimulate a positive response at any concentration tested, EC3 values of 50 and > 75 %, respectively, were assigned, according to the maximum concentrations tested in each case.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

By applying weight of evidence approach , it can be concluded that the substance is non sensitizing to the skin of mouse. Thus the chemical is classified as non-sensitizing as per the criteria of new CLP regulation.